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Important Information Concerning Small Engine Flywheels

Also check out this website: How to Balance the Rotating Assembly on a Single Cylinder Engine to Reduce Dangerous Vibration

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This section was updated 6/7/18. (Click Refresh to see changes or updates.) Scroll down or jump down to...

See the results of a cast iron Kohler flywheel with a crack in the keyway and/or when spun well above 4,000 RPM (wide open throttle)

How to Install the Ring Gear on Another Flywheel

How to Widen the Frame Rails on a Narrow Frame Cub Cadet for Use of a Large Flywheel with a Gear Starter


First of all, the flywheels on Kohler K-series and Magnum engine models K241/M10, K301/M12, K321/M14, K341/M16 and K361 will interchange, because the tapers and keyway widths are the same. The only difference is the type of starter and ignition system used. Some engines with a rope starter have magneto ignition and a 9-1/2" flywheel with no ring gear; other engines with a starter/generator and battery ignition, use either a 8" or 9-1/2" flywheel with no gear ring; some early engines with magneto ignition have a 9-1/2" flywheel with no ring gear; while most later K-series engines have battery ignition, and a 9-1/2" ring gear flywheel with internal magnets for an alternator charging system. Also, all Kohler Magnum M10-M16 engines use the same flywheel. The Kohler KT-series twin cylinder flathead engine models KT17, KT17 series 2, KT19, KT19 series 2 and KT21 (which is a snowmobile engine) use the same flywheel. And the Kohler Magnum twin cylinder flathead engine models M18 and M20 use the same flywheel.

Four types of flywheels were used on the K241-K361 K-series Kohler engines. They are as follows:

  1. From 1960 to 1973, many of the K241 and K301 engines came with an 8" diameter flywheel. The engine had battery-powered ignition, and a starter/generator provided the cranking source to start the engine and then it produced the power source to recharge the battery and power any electrical accessories. These were popular with the narrow- and wide-frame (with solid-mounted engine) IH Cub Cadets.
  2. Very few of the early K241 and K301 engines came with a 9-1/2" diameter flywheel with an unmachined edge for a starter ring gear, and there's no way to install a ring gear. These engines had a magneto ignition system. There's two magnets attached to inside the flywheel, the ignition coil is fastened on a stator to the bearing plate and a rope was used on a large notched pulley that's attached to the flywheel to crank the engine. There is no battery and no charging system involved. These were used on self-contained, stand-alone engine units, such as truck-mounted air compressors, generator/welders, water pumps, etc., and they were popular with the U.S. Military because there was no recoil starter and very few ignition parts to give trouble. Certain ignition coils are no longer available from Kohler for these engines.
  3. Another 9-1/2" diameter flywheel with an unmachined edge for a starter ring gear was also used on very few of the early K241 and K301 engines. There's no magnets inside the flywheel and no [magneto] stator. The engine had battery-powered ignition, and a starter/generator provided the cranking source to start the engine and then it produced the power source to recharge the battery and power any electrical accessories. These are popular with certain models of Case garden tractors.
  4. In 1974, the K241-K361 engines came with a 9-1/2" diameter flywheel with a machined edge for a starter ring gear and a ring of magnets on the inside. The engine had battery-powered ignition, and a small, gear type starter motor cranks the engine to start it and an alternator charging system produced the power source to recharge the battery and power any electrical accessories. These were popular with the wide-frame "Quiet Line" IH-built Cub Cadets and certain spread-frame MTD-built Cub Cadets.

And the K-series and Magnum flywheels have the same overall dimensions. The only difference is, the K-series flywheel has integrated fins (fan blades) and the Magnum flywheel use a bolt-on plastic fan blade unit, and it has an integrated magnet for the solid state ignition. The starter ring gear will also interchange between the two flywheels. As a matter of fact, the same ring gear fits the K241/M10-K341/M16 and K361 K-series and Magnum single cylinder engines, and the KT-series and Magnum twin cylinder engines.

FYI - A cast iron flywheel with a broken off fin (fan blade) will definitely run out of balance, and cause the entire engine to vibrate badly. At higher RPMs (up to 4,000 RPM), the severe vibration could also cause the sheet metal to crack at the mounting bolt holes, and in rare cases, possibly cause the crankshaft to break at the rod journal. To statically (not spinning or in motion; at rest) put the flywheel back in balance, if the entire fin is broken off, simply break off the fin directly opposite of the broken fin with a hammer. But if only part of the fin is chipped off, use an angled hand grinder or a reciprocating saw / saw saw to remove about the same amount of chipped off material from the opposite fin. Try to make the fins match each other to maintain proper balance. The flywheel should still be safe to use, and the remaining intact fins will provide plenty of fresh air to adequately cool the engine. But the best way to put the flywheel 100% back in balance is to have it dynamically precision spin-balanced with an automotive Flywheel/Crankshaft balancing machine.


The Safe and Correct Way to Remove a Small Engine Flywheel -

(Added 5/16/18) On a Kohler K-series engine with a 5/8" threaded crankshaft stud and with a starter/generator that comes in an IH-built Cub Cadet garden tractor, sometimes the aluminum clutch hub adapter that's mounted in front of the flywheel can be very stubborn to remove. This part must be removed before the flywheel shroud can be removed. So to safely remove the hub without damaging it, use the same harmonic balancer puller tool as shown below Ê to remove the hub that is used to remove the flywheel, except use two long 1/4" coarse thread grade 8 bolts with flat washers.

After the hub is removed, sometimes the 1/4" steel dowel pin will remain in the flywheel. This pin only purpose is to prevent the hub from slipping on the flywheel when engine power (torque) is applied. Anyway, when the pin gets stuck, either use locking Vise-Grips to remove the pin, or drive the pin out from the backside of the flywheel with a steel punch and hammer. When the pin is removed, it'll be a good idea to drill-out or enlarge the hole in the flywheel to 17/64" to prevent the pin from being stuck (again) if the hub needs to be removed again. If the pin fits loose in the hub, use high strength liquid threadlocker to secure the pin in the hub. And do not drill-out or enlarge the 5/8" hole in the hub! It must fit on the 5/8" crankshaft stud snug to prevent the hub from wobbling and running out of balance on the crankshaft.

To remove the flywheel from a Kohler (or virtually any) small engine, remember, the retaining nut or bolt have right-hand threads. And there's either 5/16-18 UNC (coarse thread) (small flywheels) or 3/8-16 UNC (coarse thread) (large flywheels) bolt holes for use with grade 8 bolts with a flat washer and a quality-made gear puller to remove the flywheel from the crankshaft. A hand tap may need to be used to clean the dirt and debris from the threads in the bolt holes. Remove the flywheel with a quality-made automotive harmonic balancer/vibration damper puller tool (Lisle Corporation makes a quality puller) that have fine threads and with a quality-made 1/2" impact wrench (with a large capacity [minimum 30 gallon] air compressor reservoir tank) to literally "pop" the flywheel off the crankshaft taper. Be sure the puller bolt is centered on the crankshaft, too. Avoid using an low-quality imported puller because it might move sideways when under pressure and break off the stud or bend the bolt. Use the protective cap that's supplied with the puller to prevent from damaging the threads on the end of the crankshaft. Apply grease or motor oil on the threads of the center threaded shaft to increase the pulling torque. The puller tool require either two 5/16" or two 3/8" diameter grade 8 coarse thread bolts with a thick flat washer under each bolt head so the head won't pull through the puller's slots. And use bolts that's long enough so the threads can penetrate the entire length of the threaded holes in the flywheel to prevent the threads from being pulled out. Use a tap to clean the threads in the flywheel if necessary. And although some flywheels are stubborn to remove, just remember, it'll eventually come off. It's not made on the crankshaft!

Personally, I use a quality-made 1/2" impact wrench running off of 150 psi of pressure with a 60 gallon air compressor tank and a Lisle harmonic balancer puller with grade 8 bolts w/flat washers threaded deep into the flywheel threads to remove Kohler flywheels. I ain't never had one that was so stubborn it took a lot of effort to remove. My set up pops them off every time with very little effort! You can hear the air impact wrench when it gets under a severe strain, it starts to slow down and then POW, the flywheel pops loose.

On most aluminum block engines, such as Briggs & Stratton, Tecumseh, etc., a flywheel knock-off tool can be used to remove the flywheel. You can get a knock-off tool at virtually any place that sells small engine parts, and they come in 4 different sizes: 1/2" hole for older B&S engines, 7/16-20 UNF, 1/2-20 UNF (fine thread) and 5/8-18 UNF.

To use the knock-off tool, for an older B&S engine with the crankshaft that has a long unthreaded shaft that protrudes into the starter clutch, the tool is placed on the end of the shaft, and for all other engines with a threaded stud on the end of the crankshaft, the tool is threaded onto the stud. A crowbar or pry bar is wedged under the flywheel against the engine block to provide extra leverage (and to prevent breaking the rod journal on the crankshaft if it's cast iron or bending the crankshaft if it's steel), then a 2-3 lb. hammer is used to sharply strike the tool perpendicular to literally "pop" the flywheel free from the crankshaft taper. To prevent from damaging the threads in the tool and on the crankshaft stud, always thread the tool all the way on the stud, and then back it off 1/2 turn. And don't strike the knock-off tool at an angle, or the stud on the crankshaft could get bent or break off!

But on flywheels with no threaded holes to use the automotive harmonic balancer/vibration damper puller tool, a knock-off tool of the correct thread size with a pry bar wedged under the flywheel and a 2-3 lb. hammer can be used to remove the flywheel. Be sure to strike the tool perpendicular, too!

IMPORTANT! The Incorrect and Dangerous Way To Remove A Small Engine Flywheel -

Most Kohler crankshafts are made of somewhat brittle cast iron material. So NEVER hit or strike the end of the crankshaft with a big hammer to remove a flywheel! And DO NOT attempt to use a wrecking bar (crowbar) to "pry" the flywheel off the crankshaft! Also, never use a large [2 or 3 jaw] outside-jaw gear puller to remove a flywheel. Doing any of these could damage the crankshaft and/or possibly crack or break the flywheel in half. AND DEFINITELY DO NOT USE A KNOCK-OFF TOOL WITH A BIG HAMMER ON A KOHLER CRANKSHAFT WITH THE 5/8" STUD TO REMOVE THE FLYWHEEL! Being the crank is made entirely of cast iron, the stub will likely break off!

A true story: One of my customers brought his walk-behind rotary lawn mower with a 3.5hp Tecumseh engine (model LAV35) to A-1 Miller's just to have the flywheel removed. When I had the mower on my work table to remove the flywheel, I noticed the flywheel was wobbly but still tight on the crankshaft. Then I found that the crankshaft was broken in two at the connecting rod journal. I thought, "This is odd." So I called my customer to tell him about this, and he said his neighbor tried to "pop" the flywheel off with a 10 lb. sledge hammer. (This obviously happened with the mower on the ground and the threaded end of the crankshaft was hit by the hammer at full swing.) Reminds A-1 Miller's of the old joke: "Hold my beer and watch this!"


About Crankshafts Breaking at High RPM -

A stock crankshaft should be fine as long as the engine isn't over-revved for a long period of time, which could cause it to go into harmonic vibrations, which would cause it to break in two. But if dynamically precision spin-balanced, a cast or billet steel crankshaft should survive as high as 7,000 RPM for a long time if they've been precision-balanced to the connecting rod and piston assembly using a dynamic balancing machine. Some cast cranks break, and steel crankshafts are prone to breaking, too. When they do break, it's usually due to: being in an engine that broke the connecting rod and the rotating assembly came to a "sudden stop", and the flywheel kept wanting to spin, but cracked the crank instead; an out of balance flywheel (even CNC-machined steel flywheels should be dynamically precision spin-balanced); and/or an out of balance starter pulley on the PTO end (which should also be precision-balanced). An out of balanced flywheel or pulley will cause the crankshaft to flex a few thousands of an inch at high RPM. When they flex, this causes metal fatigue, which creates a microscopic crack next to the rod journal, and they eventually break. Kind of like bending a piece of wire back and forth by hand, until it eventually breaks. I heard that the Magnum crankshafts are tougher than the old K-series cranks when precision-balanced. And when a crankshaft breaks at high RPM, it can also break a cast cam or bend a billet steel cam, which could crack the engine block at the cam pin on the flywheel side.


Always Use a Steel Flywheel on a Pulling Tractor Engine That Turns Above 4,000 RPMs!

The smaller (8") steel flywheels require that a billet pulley be installed on the PTO end of the crankshaft and a starter cart w/V-belt be used to crank the engine to start it. (Which can be a major inconvenience if you have no assistance.) And the bigger (9") steel flywheels will accept a ring gear and can be used with a gear starter fastened on the side of the engine block. (Which I think is much more convenient.) Also, the heavier (31 lb.) 9" flywheel is more suitable for stock engines that turn around 4,000 RPMs, and the lighter (19 lb.) 9" steel flywheel is ideal for engines that run at wide open throttle.

Most of the time a heavier-than-stock, custom-made, machined steel flywheel will add more "grunt" or more torque to an engine when pulling. In our experience, a light-weight flywheel will cause an engine to lose power toward the end of a pull. Light-weight flywheels are actually made for high speed racing applications, such as for drag racing or race cars. A lightweight flywheel works great for circle track racing because they allow the engine to accelerate quicker and regain the RPM after coming out of the turns. A heavy flywheel will "bog" an engine down and make it sluggish upon acceleration.

Pulling tractors on the other hand need ground speed (momentum) to do well in a pull, with the use of a heavier-than-stock flywheel. Once a heavy flywheel is spinning, it's hard to stop it or slow it down. A heavy flywheel may somewhat cause a [stock] engine to rev up slower, but once it's revved up, and because of the greater momentum force or increase of weight in the rotating mass, it'll "hold" the RPM longer, allowing a tractor to pull the sled right out the gate.

Remember, there's only two things to be gained by using a heavy steel flywheel; 1: the safety of steel versus cast iron, and 2: the increase in rotating mass with use of a heavier-than-stock flywheel. This means that a heavy flywheel will help an engine to produce more torque at higher RPM, which is very important for a pulling engine. A heavy flywheel (heavier-than-stock) will, without a doubt, will add more lugging power to an engine. That's why they're used on the large farm tractors. By the way - the average 9-1/2" diameter OEM (Original Equipment Manufacturer) cast iron flywheel for the single cylinder K241-K361 Kohler K-series engines with the starter ring gear and full integrated fins (fan blades) weighs 23-24 lbs.

By the way - covering a shiny (new) billet steel flywheel with clear gloss enamel acrylic coating will help identify it visually as made of steel. Otherwise, if it's covered with colored paint, it'll be somewhat difficult to tell right away rather if it's a factory cast iron or steel flywheel. The enamel coating will also help protect the steel flywheel from rusting over time. (I think a nicely painted pulling engine looks good with a shiny [clear coated] steel flywheel.) Actually, the best way to determine if an engine has either a cast iron or steel flywheel (if they look the same) is to tap it with a small hammer or wrench. Cast iron will make a "clunk" sound, and steel will have a high pitch ring to it.

Here's the dimensions if you want to fabricate a 9-1/2" diameter steel flywheel for the K241-K361 single cylinder Kohler engine:

If the above dimensions are somewhat confusing, then perhaps it's best to acquire a Kohler flywheel and take the measurements off of it. Or for a steel flywheel, visit Midwest Super Cub's website.

By the way - the flywheels for Kohler K-series and Magnum engine models K241/M10, K301/M12, K321/M14, K341/M16 and K361 will interchange because they all have the same size taper on the crankshaft and in the flywheel, and most of them have two or four threaded holes for driving accessories, and for using an automotive harmonic balancer/vibration damper puller tool to remove the flywheel from the crankshaft. Also, the same flywheel ring gear (gear starter) for Kohler engine models K241/M10, K301/M12, K321/M14, K341/M16, K361, KT17, KT17 series 2, KT19, KT19 series 2, MV16, M18, MV18, M20 and MV20 will interchange. They are all identical.

And adding a heavy pulley on the PTO end of the crankshaft would help add torque to the engine at high RPM. But if/when the engine bogs down upon launch at the starting line or several feet from the starting line, it may be hard to get it to rev back up due to the extra spinning weight. So you gain one thing, but may lose another.


IMPORTANT! NEVER INSTALL A DIRTY FLYWHEEL ON A DIRTY CRANKSHAFT!

Before installing the flywheel on a crankshaft, always thoroughly clean both tapers with a clean cloth (white in color, to see the dirt) or clean shop towel to remove any dirt, oil or debris from the crankshaft taper and most importantly, inside the flywheel taper. It's okay to use electrical contact cleaner, brake parts cleaner, cleaning solvent or paint thinner to clean the tapers because these products leave no oily residue when they dry. And use emery cloth to remove any light rust on the surface of the tapers. Clean both tapers thoroughly. This is very important because there must be direct metal-to-metal contact between the tapers for a secure bonding of the two parts. Because the flywheel must keep up with the rapid acceleration (torque or driving force) of the piston via the crankshaft. DO NOT USE GREASE OR ANTI-SEIZE LUBRICANT ON THE CRANKSHAFT AND FLYWHEEL TAPERS FOR EASY REMOVAL OF THE FLYWHEEL LATER! This applies to any type of flywheel; aluminum, cast iron or steel. If a flywheel with a taper needs to be removed for whatever reason, it's supposed to be hard to remove. Anti-seize lubricant works great for the threads on bolts in certain situations, but NOT for flywheels and crankshaft tapers. For assurance, high strength liquid threadlocker (Red Loctite, Permatex or equivalent) can be applied inside the flywheel taper or on the crankshaft taper to prevent the flywheel from slipping on the crankshaft. Thorough cleaning of the tapers should still be performed even with the use of the threadlocker. Be sure to allow the threadlocker to fully cure (dry/harden) overnight at room temperature before starting the engine because if the threadlocker is still in liquid form, the rapid torque of the acceleration of the engine could cause the flywheel to slip slightly and possibly loosen on the crankshaft.

If the threadlocker is used, an acetylene torch will be required to soften the threadlocker in order to remove the flywheel. If the flywheel needs to be removed later, use a quality gear puller and an air impact wrench or some muscle. Any oil, dirt or debris trapped in the tapers, or even anti-seize, will, without a doubt, allow the flywheel to slip or rock back and forth on the crankshaft, in which will shear the key, wallow out both keyways and possibly crack or break the flywheel and/or crankshaft. Dirt/oil on the tapers is the main reason why most custom-made billet steel high-performance crankshafts break. And if the flywheel use a Cub Cadet or billet aluminum clutch hub adapter, be sure to install the [1-3/8" o.d.] thick flat washer under the retaining nut or bolt and then torque the nut or bolt to the proper specs.

NOTE: As long as the rotating clutch components are trued-up in a metal lathe to minimize vibration, and the wide, thick washer is used inside the hub to secure the hub to the flywheel, and the flywheel retaining nut or bolt properly torqued, the OEM (Original Equipment Manufacturer) cast aluminum clutch hub have been proven to hold up to a wide open throttle pulling engine. IMPORTANT: If you don't feel comfortable using a metal lathe, please consult a professional and experienced machinist with a lathe.


IMPORTANT! A cast iron flywheel with a crack in it, even a small crack, should never be used on any engine!

Oil, grease, dirt or any kind of debris in the flywheel taper and/or on the crankshaft taper, or even an overtorqued nut or bolt, could cause the center in a cast iron flywheel to crack in the keyway or the threaded stud of the crankshaft to break off. Cast iron flywheels always crack at the weakest point, which is at the keyway. If the crack is welded, and when the flywheel is installed on the crankshaft, and the nut or bolt is torqued to specs, the taper would still split next to the weld. But steel flywheels don't crack (or break). For a steel flywheel, visit Midwest Super Cub's website.

A crack in a flywheel will cause an engine to vibrate severely, plus it'll be noisy. (It'll make a "clunk, clunk" sound at idle.) The crack will get worse over time, causing the flywheel to split in half at high RPM. If this happens, the two halves could cause severe bodily injury or possibly death if they were to become airborne and strike an innocent bystander.

The only valuable part on a cast iron flywheel with a crack in the keyway would be the starter ring gear. It can be installed on a [good] cast flywheel or a steel flywheel. Cast iron flywheels that's in good condition works great up to 4,000 RPM. (The factory setting of maximum RPM for virtually all small gas engines, including all of Kohler engines is 3,600.) Above 4,000 RPM, a steel flywheel is highly recommended for safety.

To minimize damage to the keyways, do not use a steel flywheel key. A heat-treated hardened key would be even a worse thing to use. An soft aluminum (4041 hardness) key works best. To keep a keyway in a cast flywheel from splitting, it's best to use soft aluminum key. The reason for this is if the connecting rod breaks resulting in instant crankshaft lockup, the soft key will prevent damage to the flywheel and crankshaft. The aluminum key will shear in two, allowing the flywheel to slip on the crankshaft, preventing damage to either the flywheel or crankshaft. A steel key will cause a cast iron flywheel to crack or break, or if a flywheel loosens on the crankshaft, it'll wallow out the keyways. But if an aluminum V-belt starter pulley with ignition timing degree marks is installed on the PTO end of the crankshaft, there's really no need to install a flywheel key. The only reason most small engines use a flywheel key is to time the ignition, and not to prevent the flywheel from slipping on the crankshaft.


The Best Way to Torque the Flywheel Retaining Bolt or Nut - [Top of Page]

Personally, I use an air impact wrench to lightly snug the flywheel nut or bolt against the flywheel, then I finish torquing it with a torque wrench. The flywheel won't rotate with an air impact wrench. If an air impact wrench isn't available, and if the flywheel has a starter ring gear, clamp Vise Grips on the edge of the ring gear, allow it to bump against the bolt boss on the bearing plate and then the flywheel nut or bolt can be loosened to be removed, or when installing, torqued to specs. But if the flywheel doesn't have a ring gear, clamp the Vise Grips on the PTO end of the crankshaft, install a long bolt in one of the bolt holes on the PTO end of the block, and allow the Vise Grips to bump against the bolt to loosen or torque the flywheel nut or bolt. As easy and simple as this may be, do not place a steel bar through the fins of the flywheel to loosen or torque the bolt or nut! Being the fins are made of brittle cast iron, doing this could cause a fin to break off. If a fin breaks off, this will cause the flywheel to be dangerously out of balance, and the engine will vibrate badly.

With the tapers clean, and when the flywheel nut or bolt is tightened or torqued to specs, the "squeezing" action of the flywheel taper actually "grips" it to the crankshaft, guaranteeing 100% metal to metal contact, and torque the 3/8" bolt to 40 ft. lb. or 15/16" nut to 65 ft. lb. Do not use an impact wrench because this may overtighten the bolt/nut and cause the flywheel to crack/split at the keyway slot. And OEM Kohler's flywheel castle nut is self tightening, requiring no lock washer. But use a split lock washer on the bolt, and use a new grade 8 bolt, nothing less.


Shielding of the Flywheel is Important!

I remember years ago, I was reading a club's rules, and it stated that all tractors must have a steel flywheel, and it must be shielded 360º with minimum 1/4" thick steel. I asked one of the pullers of the club, "why shield a steel flywheel? It's not going to break." And he told me: "There's a possibility that the end of the crankshaft could break off."

Actually, it's not rare that this kind of thing happens. It's happened to various pullers. The end of a crankshaft, despite if it's steel or cast iron, can break off next to the flywheel. It's a slight possibility. But then again, it could happen. Like the old saying goes: "A bad apple will spoil the bunch." And remember Murphy's Law? Must be prepared for the unexpected. So need to shield them flywheels folks, before a catastrophe happens.


IMPORTANT! IMPORTANT! IMPORTANT! IMPORTANT!
Below Ê are the results of a OEM Kohler cast iron flywheel that is out-of-balance, with a crack in the keyway, a broken-off fin, and/or when spun at wide open throttle

IMPORTANT! Due to its brittle material, a cast iron flywheel (altered or unaltered) shouldn't be used on an engine that runs higher than 4,000 RPM or at wide open throttle. Due to the combination of severe centrifugal force and normal engine vibration, the flywheel could explode, causing serious injury or possible death to a bystander. The Kohler Magnum plastic flywheel fan shouldn't be ran above 4,000 RPM either, because it can explode, too. And NEVER use an automotive tire bubble balancer to balance a flywheel! Also, make sure the flywheel has all the internal magnets intact (for the charging system) or remove the magnets altogether if using no charging system. And do not spin a cast flywheel (on the engine) no faster than 4,000 RPM! Or better yet, install a billet steel flywheel and an electric fan to cool the engine. Check out this video: Farmall 1206 Breaks in Half when flywheel Explodes - YouTube and check out other YouTube videos of flywheels exploding. This is why shielding the flywheel (and clutch assembly) 360º with heavy plate metal is so important!

The photos below Ê are the results of a 9-1/2" diameter cast iron Kohler flywheel when it was spun at wide open throttle in a garden pulling tractor. This was a very serious accident that could have been a life-threatening tragedy. Remember: a well-constructed and precision-balanced steel flywheel is cheap compared to hospital bills, rehabilitation or funeral costs and not to mention the seemingly never-ending lawsuits! For a steel flywheel, visit Midwest Super Cub's website.

The guy (name withheld) had just recently bought the Pro Stock motor. He already had the clutch setup on the flathead Kohler twin he was running. According to what a friend of his told A-1 Miller's (that also has a Pro tractor) the guy called him and asked would it be ok just to start the motor so he could hear it run. He was told not to turn it over 3,000 RPM. There is no question the guy knew he needed a steel flywheel and safety shields on the tractor before pulling it. I am confident those measures would have been on it before he pulled it the first time. There "was" someone standing by the tractor - the guy that owns it. He was working the throttle standing right in-line with the cast iron flywheel. You can see what it did to the air filter. Apparently it hit the carburetor and filter on its way to hitting him. It wasn't his leg that got the brunt of the piece of flywheel!

He just got too eager to find out what he had purchased and made a bad decision. It's an injury that will be with him the rest of his life. The point of putting these pictures on this site is so other pullers would not make the same mistake. I'm confident he is embarrassed by his actions...but he didn't have to share those pictures, ya know. I admire him for sharing these photos, and he's still suffering from the accident. - Story by Ron Ethridge

IMPORTANT! It's highly recommended that all flywheels, despite the material it's made of, be dynamically precision spin-balanced with an automotive Flywheel/Crankshaft balancing machine. The same machine to balance a crankshaft can be used to balance a flywheel, too. And never use an automotive tire balancer or "bubble balancer" to balance a flywheel! They are NOT precision enough for a flywheel!

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If you would like to purchase any of the parts or services listed in this website, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO (Missouri) 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell; text or when leaving a voice message, please speak slowly and clearly). Please call Monday-Friday, except holidays, 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) E-mail: pullingtractor@aol.com. When you call, text, email or visit our shop, you will be dealing directly with the owner for the best customer service. A-1 Miller's shop is open to the public from 9am to 5pm, including weekends, except holidays. Please call before coming so I'll be here waiting for your arrival. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. If you're the kind of person who don't trust delivery/shipping companies (mis)handling your high-dollar and fragile merchandise, you can make the long drive to A-1 Miller's shop to personally purchase parts, or drop off and/or pick up your carburetor, clutch assembly, engine parts, entire engine, transmission, transaxle, entire garden tractor, etc. for repairing and/or rebuilding. "The road to a friend's house (or shop) is never long." (We're planning to relocate our business to other property with a bigger and better shop so we can provide many more high quality parts and professional services.)
High Quality Inductive Handheld Small Engine Wireless Tachometer. A tachometer is required in setting the correct RPMs (normally 3,200 or 3,600 maximum for small engines) of an engine to prevent from over-revving and possible damage to the engine or dangerous flywheel explosion. For gas/spark ignite engines only. Works with magneto and battery-powered ignition systems. Very accurate. This handheld analog tach works great for checking/setting the RPM on various small engines in the shop, and/or for checking/setting the RPM [tech] on stock governed competition pulling engines. Hold sensor (antenna) close to spark plug wire for reading. Operates off a self-contained replaceable 9 volt battery. Has built-in battery voltage check. Reads up to 5,000 RPM on the low scale, and 15,000 RPM on the high scale.
  • $85.00 each, plus shipping & handling.
High Quality Inductive Small Engine Tachometer/Hour Meter. A tachometer is required in setting the correct RPMs (normally 3,200 or 3,600 maximum for small engines) of an engine to prevent from over-revving and possible damage to the engine or dangerous flywheel explosion. Very accurate. Can be used for lawn & garden equipment or competition pulling engines. Can be hand-held to temporarily set engine RPM or permanently mounted to monitor engine RPM at all times. Large 3/8 inch LCD display. Works with magneto and battery-powered ignition systems. Works with all spark ignition engines by selecting engine type using S1 and S2 buttons. If tachometer does not turn on automatically as soon as engine starts, press and hold the two buttons at the same time. Instructions included. Tachometer reads up to 99,999 RPM. Hour meter reads up to 9999:59 hours/minutes then resets to Zero. Programmable maintenance hour setting with service icon, a reminder when to change oil or other service. Can be manually reset to Zero hours. Programmable maintenance hour setting with service icon, a reminder when to change oil or other service. Easy installation: Single wire wraps around spark plug wire and secured with two supplied nylon zip-ties. No wire terminal connections required. Tachometer can be surface-mounted and secured with two screws. Has battery that last up to 4 years. Sealed unit; weather and water resistant. Dimensions: 2" wide x 1-3/4" depth x 3/4" height.
  • $20.00 each, plus shipping & handling.
High Quality Digital Tachometer/Proximity Sensor Kits. A tachometer is required in setting the correct RPMs (normally 3,200 or 3,600 maximum for small engines) of an engine to prevent from over-revving and possible damage to the engine or dangerous flywheel explosion. Choice of a RED or BLUE numeric display. Will work with single- or twin-cylinder small engines or multi-cylinder automotive engines, gas or diesel. The great thing about this type of tachometer is it needs no setup. It displays accurate RPMs as soon as the engine cranks over to start. Displays up to 9,999 RPM. Very accurate. Tachometer returns to zero [0000] when engine is shut down. Operates totally independent of the ignition system. Can be used for lawn & garden equipment or competition pulling engines. Designed to be permanently mounted to monitor engine RPM at all times. Tachometer can be in-dash or panel-mounted. This precision digital tachometer operates with external power and on the same principle as my flywheel- or crank-trigger ignition systems with a proximity sensor to detect the target, which can be a small ferrous steel screw or pin, or magnet in a rotating disc on the crankshaft or on/in flywheel. A sturdy steel or aluminum bracket will need to be fabricated by customer to mount the sensor in close proximity of the detector/trigger target. Set air gap/clearance at .010"-.188". Tachometer works with 8-24 volts DC, proximity sensor works with 6-36 volts DC. Dimensions for mounting hole for tachometer: 3" wide x 1-17/32" wide. Tachometer measures 1" in depth. Dimensions of proximity sensor: 15/32" diameter x 1-3/8" thread length. Wiring Instructions: #1 wire on tachometer connects to brown wire on proximity sensor and ignition switch (12 volt power), #2 wire on tachometer connects to blue wire on proximity sensor and engine/chassis ground (battery negative (–) post), and #5 wire on tachometer connects to black wire on (either) proximity sensor. Wires #3 and #4 connects to nothing. Wiring is the same for the hall effect and inductive proximity sensors. Some proximity sensors have an LED (Light Emitting Diode) on the rear of unit. If the proximity sensor is wired incorrectly, the LED will illuminate within the target. Click or tap here for YouTube videos to see how well this tachometer works. Cannot be wired in conjunction with the Dynatek Dyna S or PerTronix Ignitor ignition modules. This tachometer must be wired separately or wiring can be integrated with my crank-trigger ignition system that use a proximity sensor.
  • Tachometer only. Use with virtually any Normally Open 3-wire hall effect, inductive, or cube-shaped inductive proximity sensor (w/flywheel trigger ignition). $22.00 each, plus shipping & handling.
  • Complete Tachometer Kit with Hall Effect Proximity Sensor (dimensions below) and Locking Set Screw Collar w/Embedded Magnet. When ordering, please indicate diameter of crankshaft PTO end for locking collar. $47.00 each, plus shipping & handling.
  • Complete Tachometer Kit with Inductive Proximity Sensor (dimensions below). Senses the head of a small steel screw installed in a rotating locking set screw collar, disc or flywheel. $32.00 each, plus shipping & handling.
  • Hall Effect Proximity Sensor. Dimensions: 15/32" Diameter x 2-1/2" Length x 43" Cable Length . (Senses the South pole of a small magnet embedded in an aluminum rotating locking set screw collar, disc, or OEM magnet embedded externally in a flywheel.) $10.00 each, plus shipping & handling.
  • Inductive Proximity Sensor. Dimensions: 15/32" Diameter x 2-1/2" Length x 43" Cable Length Inductive Proximity Sensor. (Senses the head of a small steel screw in a rotating locking set screw collar, disc or flywheel.) $13.00 each, plus shipping & handling.
  • Aluminum Locking Set Screw Collar w/Embedded Trigger Magnet. Use with hall effect proximity sensors only. $15.00 each, plus shipping & handling.
  • Steel Locking Set Screw Collar w/Steel Trigger Screw Head. Use with inductive proximity sensors or magnetic pickup coils. $15.00 each, plus shipping & handling.
  • When ordering either locking collar above, please specify diameter of crankshaft PTO end or shaft it's to be mounted on. Most common Kohler crankshaft PTO end diameters are 1", 1-1/8", but 3/4", 1-1/4", 1-3/8", 1-7/16" and 1-1/2" are rare. Most billet steel crankshafts have a 1-1/2" diameter PTO end (raised shoulder). Other sizes available. [Return to previous section]
Superior Quality, High Velocity 12 Volt Engine Cooling Fan. Use an electric fan to cool a competition garden tractor pulling engine with a steel flywheel. Motor is 100% secured and reinforced in plastic fan housing tube to withstand severe engine vibrations, and to prevent motor from loosening and become inoperable due to normal engine vibrations when pulling. Modification made by Brian Miller. No need to mount fan housing on rubber grommets; they will serve no purpose whatsoever with this fan. Fasten fan housing on a sturdy angle steel support brace with 1/4" bolts, lock washers and wide, flat washers in front of engine or behind grille in a Cub Cadet garden tractor aimed at the exhaust area of engine. Draws 2.6 amps, produces 145 CFM. Measures 3" diameter and 5" length. IMPORTANT! Due to normal engine vibrations, do not run fan while pulling because the brushes that make contact with the commutator could break! If tuned correctly and the carburetor air/fuel mixture is set correctly, the engine should not severely overheat during the 2-3 minutes of pulling down the track. Turn fan on ONLY between pull-offs or when tuning engine or adjusting carburetor. $35.00 each, plus shipping & handling.

Kohler K181 Flywheel for the 5-1/2" 15/20 Amp Charging Stator. Replace damaged flywheel, or use this type of flywheel with the 5-1/2" stator to convert a K181 engine with a stator containing a failed magneto ignition coil integrated with a weak output 10 amp charging coils under the flywheel to the battery-powered ignition system. OEM Kohler part # 41 025 17-S.
  • Used and in excellent condition. $250.00 each, plus shipping & handling. (When available.)
  • New. $505.08 each, plus shipping & handling.
Precision Dynamic Spin-Balancing Service -
  • Balance (cast or steel) flywheel for Kohler 10-16hp cast iron block engine. $75.00 each labor, plus return shipping & handling.
  • Balance cast iron (Kohler) crankshaft and matching connecting rod and piston assembly. $260.00 per rotating assembly, plus return shipping & handling.
  • NOTE: When shipping your crankshaft, connecting rod and piston assembly, and/or flywheel to A-1 Miller's address to be balanced, please enclose the crankshaft, connecting rod and piston assembly in two USPS Large Flat Rate Boxes. Place one box inside the other to double the strength, and use rigid packing material to prevent the parts from damage during shipment. [Return To Previous Paragraph, Section or Website]

  • Regrind Crankshaft Journal - $75.00 per journal, plus return shipping & handling. Note: The K241-K361 Kohler crankshafts can be ground as far as .030" and still be safe to use with a matching undersized bearing insert installed in the rod. And all crankshafts, rather if they're automotive or small engine, are checked for straightness before grinding. If they're bent or twisted, sometimes they can be straightened.
  • On the Kohler engine models K141, K160/K161 or K181/M8 and other makes and models of engines, if the crankshaft is worn beyond .010" and needs to be reground again, the journal can be reground to .020" and then the connecting rod can be resized so it'll fit the smaller undersize journal. I do this sometimes on engines when a .020" undersize rod isn't available. This hurts nothing and it lasts as long as an ordinary STD rod and crank journal. Price for doing this is $75.00, plus return shipping & handling. I will need your crankshaft and connecting rod.
  • Repair a broken off stud in crankshaft on flywheel end: $20.00. I drill and cut threads for a hardened 3/8" or 5/8" diameter bolt in the end of the crankshaft to secure the flywheel. And a steel bolt is much stronger than a cast iron stud. Because cast iron is brittle and steel is flexible.
  • Drill and cut 7/16-30 UNF (fine thread) threads in the PTO end of the crankshaft for a retaining washer and bolt. $20.00.
A-1 Miller's Crankshaft Machine Repair Service - (Added 2/3/21)
  • Drill and tap flywheel end of Kohler K-series crankshaft for installation of 3/8" bolt when threads on integrated 5/8" stud are damaged beyond rethreading or when 5/8" stud breaks off. No need to purchase another high-dollar, hard to find crankshaft. Precision work performed in large metal lathe. Hardware include: 3/8-24 UNF grade 8 bolt, split lock washer and 3/8" x 5/8" adapter step washer. $55.00 for labor and hardware.
  • Drill and tap PTO end of Kohler crankshaft for installation of 3/8" bolt to retain electric PTO clutch or billet starter pulley. Precision work performed in large metal lathe. Hardware include: 3/8" grade 8 bolt, split lock washer and extra thick flat washer. $45.00 for labor and hardware.
  • Drill and tap flywheel end of Kohler K-series crankshaft for installation of 5/8" threaded steel stud when threads on integrated 5/8" stud are damaged beyond rethreading or when 5/8" stud breaks off. No need to purchase another high-dollar, hard to find crankshaft. Precision work performed in large metal lathe. Hardware include: Installation of 5/8-18 UNF stud, self-locking flywheel retaining nut and extra thick flat washer. $75.00 for labor and hardware.
Flywheel Retaining Nuts for threaded stud on end of K-series and steel crankshafts. IMPORTANT: Apply thin coat of motor oil on threads of crankshaft before installing nut then torque each to 65 ft. lbs.
  • OEM-Type Slotted/Tapered Seat Self-Locking Nut. 5/8-18 UNF (fine thread) threads. A-1 Miller part. Discontinued from Kohler. Replaces Kohler part # 25 100 02-S. $1.50 each, plus shipping & handling.
  • All-Metal Self-Locking Nut. 5/8-18 UNF (fine thread) threads. $1.50 each, plus shipping & handling.
  • OEM-Type Slotted/Tapered Seat Self-Locking Nut. 3/4-16 UNF (fine thread) threads. Used on older K241 crankshafts and most billet steel crankshafts. A-1 Miller part. Discontinued from Kohler. Replaces Kohler part #'s X-89-11, X-119-16. $1.75 each, plus shipping & handling.
  • All-Metal Self-Locking Nut. 3/4-16 UNF (fine thread) threads. Used on older K241 crankshafts and most billet steel crankshafts. $1.75 each, plus shipping & handling.
Flywheel Retaining Bolt and Washer Kit. Fits Kohler and various other makes and models of small engines with a 3/8" threaded hole in flywheel end of crankshaft. Includes: 3/8-24 UNF grade 8 bolt, split lock washer and extra thick flat washer. IMPORTANT: Apply thin coat of motor oil in threads of bolt, then torque to 40 ft. lb. High quality aftermarket. Replaces OEM Kohler part #'s 25 068 04, 25 068 24, 47 086 16, 47 086 18, 52 068 25 (bolt) and 12 468 03-S, 52 114 02, 52 468 15 (washer). $5.00 per kit, plus shipping & handling. Safety Retaining Bolt and Washer Kit for Starter Pulley on PTO end of crankshaft or Harmonic Balancer on automotive crankshaft (mini rod). Prevents starter pulley or harmonic balancer from dislodging on crankshaft, and becoming an airborne projectile, which can cause serious injury to a bystander or spectator. Kit includes: 3/8-24 UNF or 7/16-28 UNF grade 8 bolt, split lock washer and 1-3/8" O.D. flat washer. Please indicate if you need the kit for a 3/8" or 7/16" bolt. A-1 Miller's aftermarket parts. $5.00 per kit, plus shipping & handling.
Extra Thick Flywheel / Aluminum Hub Adapter Retaining Washers. A must to secure flywheel and prevent OEM Cub Cadet or billet aluminum hub adapter breakage. Each made of steel and measures approximately 1/4" thick x 1-1/4" o.d.
  • Washers with 13/32" center hole. To be used with a crankshaft that has a 3/8" bolt, and/or aluminum hub adapter that has a 3/8" center hole.
    • A-1 Miller part. $3.00 each, plus shipping & handling.
    • OEM Kohler part # 12 468 03-S. $3.80 each, plus shipping & handling.
  • Washer with 5/8" center hole. To be used with a crankshaft that has a 5/8" stud, and/or aluminum hub adapter that has a 5/8" center hole. A-1 Miller part. Discontinued from Kohler. Replaces Kohler part # X-25-104. $5.00 each, plus shipping & handling.
  • Washer with 3/4" center hole. To be used with a crankshaft that has a 3/4" stud, and/or aluminum hub adapter that has a 3/4" center hole. A-1 Miller part. Discontinued from Kohler. Replaces Kohler part # X-25-71. $5.00 each, plus shipping & handling.
Steel Adapter Step-Washer for installing Cub Cadet cast aluminum clutch hub with 5/8" center hole to Kohler Magnum crankshaft with a 3/8" bolt. A must to center hub and prevent hub breakage! NOTE: As long as the rotating clutch components are trued-up in a metal lathe to minimize vibration, and the wide, thick washer is used inside the hub to secure the hub to the flywheel, and the flywheel retaining nut or bolt properly torqued, the OEM cast aluminum clutch hub have been proven to hold up to a wide open throttle pulling engine.
  • $12.00 each, plus shipping & handling.
Square Aluminum Flywheel/Crankshaft Key. Made of 6061 medium-grade hardness alloy aluminum. Fits Kohler engine models K141, K160, K161, K181, M8, K241, K301, K321, K341, K361, KT17, KT17 Series II, KT19, KT19 Series II, MV16, M18, MV18, M20 and MV20 made in 1973 and later. Helps prevent damage of keyway in crankshaft and/or prevents the possibility of cracking/breaking of factory cast iron flywheel due to sudden crankshaft lock-up in the event of connecting rod failure. Dimensions: 3/16" square x 1-3/8" length. IMPORTANT: Thoroughly clean tapers inside flywheel and on crankshaft before installing flywheel! An ingenious and innovative concept by Brian Miller. Please accept no advertised copycat products of this kind. (But I do appreciate them acknowledging my ingenuity and intelligence.) A-1 Miller's part. Replaces Kohler [steel key] part # X-286-17-S. $5.00 each, plus shipping & handling.


Rectangular Steel Flywheel/Crankshaft Key. Fits Kohler engine models K241, K301 and K321 made in 1972 and earlier with the 8" diameter flywheel and starter/generator. Also fits Kohler engine models K330/K331. Dimensions: 3/16" wide x 1/4" tall x 1-3/8" length. IMPORTANT: Thoroughly clean tapers inside flywheel and on crankshaft before installing flywheel!

  • Used and in excellent condition. Discontinued OEM Kohler part # X-366-1-S. $5.00 each, plus shipping & handling. (When available.)


Square Steel Flywheel/Crankshaft Keys. Fits Kohler engine models K141, K160, K161, K181, M8, K241, K301, K321, K341, K361, KT17, KT17 Series II, KT19, KT19 Series II, MV16, M18, MV18, M20 and MV20 made in 1973 and later. Dimensions: 3/16" square x 1-3/8" length. IMPORTANT: Thoroughly clean tapers inside flywheel and on crankshaft before installing flywheel!

  • High quality aftermarket. Made of mild steel. Replaces Kohler part # X-286-17-S. $1.00 each, plus shipping & handling.
  • OEM Kohler part # X-286-17-S. $2.10 each, plus shipping & handling.


Woodruff (Semicircular) Steel Flywheel/Crankshaft Key. Fits most OHV aluminum block Kohler engines. Dimensions: 3/16" wide x 5/8" length. IMPORTANT: Thoroughly clean tapers inside flywheel and on crankshaft before installing flywheel!

  • High quality aftermarket. $1.00 each, plus shipping & handling.
  • OEM Kohler part # X-42-15-S. $1.70 each, plus shipping & handling.


Woodruff (Semicircular) Steel Keys for Flywheel/Crankshaft and Gear Reduction Shaft on certain Kohler engine models K241, K301, K321, K341, and all Magnum models M10, M12, M14, M16, and models CH13 and CH15. Dimensions: 3/16" wide x 1" length. IMPORTANT: Thoroughly clean tapers inside flywheel and on crankshaft before installing flywheel!

  • High quality aftermarket. $1.00 each, plus shipping & handling.
  • OEM Kohler part # X-46-3-S. $2.25 each, plus shipping & handling.
Flat washer for retaining flywheel or aluminum clutch hub to flywheelFlywheel / Aluminum Hub Retaining Washers. A thick, wide washer is a must to secure flywheel and prevent clutch/driveshaft aluminum hub adapter breakage! Each made of steel and measures 1-1/4" o.d. x approximately 1/4" thick.
  • Washer w/13/32" hole. Must be used with aluminum hub that has a 3/8" hole.
    • A-1 Miller part. $3.00 each, plus shipping & handling.
    • OEM Kohler part # 12 468 03-S. $3.40 each, plus shipping & handling.
  • Washer w/5/8" hole. To be used with aluminum hub that has a 5/8" hole. A-1 Miller part. (Discontinued from Kohler.) Replaces Kohler part # X-25-104. $3.50 each, plus shipping & handling.
  • Washer w/3/4" hole. To be used with aluminum hub that has a 3/4" hole. A-1 Miller part. (Discontinued from Kohler.) Replaces Kohler part # X-25-71. $3.50 each, plus shipping & handling.
Steel Adapter Step-Washer for installing Cub Cadet cast aluminum clutch hub with 5/8" center hole to Kohler Magnum crankshaft with a 3/8" bolt. A must to center hub and prevent hub breakage! NOTE: As long as the rotating clutch components are trued-up in a metal lathe to minimize vibration, and the wide, thick washer is used inside the hub to secure the hub to the flywheel, and the flywheel retaining nut or bolt properly torqued, the OEM cast aluminum clutch hub is capable of holding up to a wide open throttle pulling engine.
  • $12.00 each, plus shipping & handling.
1/4" Steel Dowel Pin for aluminum clutch hub. 3/4. Secures above hub to flywheel to prevent slippage.
  • $1.00 each, plus shipping.

How to Install the Ring Gear on Another Flywheel -

The same flywheel ring gear (gear starter) for Kohler engine models K241/M10, K301/M12, K321/M14, K341/M16, K361, KT17, KT17 Series 2, KT19, KT19 Series 2, MV16, M18, MV18, M20 and MV20 will interchange. They are all identical. To swap a starter ring gear from one flywheel to another, first of all, Kohler don't sell just the ring gear by itself. You will need to acquire a used flywheel with a good ring gear on it.

  1. To remove the ring gear from a flywheel, it's not necessary to heat it. Instead, place the flywheel with the fins facing up on a steel top work table, bench or concrete floor, then use a drift punch tool or steel rod and a 2-3 lb. hammer to remove the ring gear from the flywheel. Gently tap equally around the entire circumference of the gear to avoid distorting or bending it. It should eventually fall off.
  2. To install the ring gear on a flywheel, position the flywheel with the fins facing down on a fire-proof steel top work table, bench or concrete floor, and place the ring gear on the flywheel with the beveled edge of the gear teeth facing upward. This allows the starter gear teeth to engage more easily without causing binding, damage or wear to the teeth.
  3. Use an oxy-acetylene torch to heat the ring gear 360º to expand it so it'll install on the flywheel. (A propane torch may not get hot enough.) This should only take a few minutes. Do not use a hammer for assistance! Once the gear drops in place, it'll have a loose fit until it cools. Allow it to air-cool. Do not cool it with water. Once cooled, it'll have a tight, secure fit on the flywheel. NOTE: NEVER attempt to install (pound) a [cold] ring gear onto the flywheel with a hammer! Doing this will bend it badly out of shape and ruin it for use.
  4. Click here to watch various YouTube videos of this process: How to swap or flip a ring gear off a flywheel - YouTube (https://www.youtube.com/results?search_query=How+to+swap+or+flip+a+ring+gear+off+a+flywheel).


How to Widen the Frame Rails on a Narrow Frame Cub Cadet for Use of a Large Flywheel with a Gear Starter - (This is much easier to do on a platform work table.)

On a garden pulling tractor, it's best to use a gear starter with the larger diameter flywheel, because a starter/generator will rob the engine of valuable horsepower, which needs to be put through the rear tires. It'll be better to spin the tires than the starter/generator. As an added bonus, the bigger (heavy, steel) flywheel will add horsepower and torque to the engine at high RPMs.

The larger 9-1/2" diameter flywheel with a starter ring gear, larger K-series bearing plate and K-series flywheel housing can be installed on any K241-K361 Kohler engine for use with the gear starter, as long as there's an indentation in the block just above the starter motor's mounting holes (when using the upper-mount type starter). (The small flywheel is 8" in diameter.) If the engine is being installed in a narrow frame Cub Cadet (models 70, 71, 72, 73, 100, 102, 104, 106, 122, 124 and 126), the frame rails must be widened to accept the larger flywheel, bearing plate and flywheel housing. No charging system is required or recommended for a pulling tractor because it'll rob horsepower and add unnecessary weight and extra wiring. Read below for information on how to convert a narrow frame Cub Cadet.

If you want to do away with the old, heavy, battery draining, power-robbing starter/generator on a narrow frame Cub Cadet and install a lightweight gear starter along with the larger 9-1/2" diameter geared flywheel on a Kohler engine, you'll have to widen the frame rails. To do this, with the engine removed, cut a slot halfway down into the frame where the front of the flywheel shroud sits. For the rear cut, measure 17" back from the front of the frame (to where the metal bends for the clutch cover), and then make the cut there. Then using a large pipe wrench or very large Crescent wrench (I found either of these work great), bend or spread the frame rails outward 11" from the front of the frame. Use a (large) flywheel shroud as a gauge to determine how wide the rails will need to be. This will eliminate having to put the engine in and take it out again. Spread the frame 5" forward (towards front of tractor) from where the slot was cut. Check to see that the frame rails are bent upward from spreading out the metal. (Hold a straight edge tool under each frame rail to check for straightness.) If the widening process was performed correctly, then they shouldn't be bent. If they are bent, they will need to be straightened so the driveshaft/clutch will be in correct alignment with the engine. It'll be best to securely weld two full-length 1/4" thick x 1-1/2" wide steel pieces under each frame rail to reduce the chance of bending. Then securely weld a 1/8" thickness mild steel gusset plate (angle reinforcement brace) into each wedge/cut) opening. A Magnum flywheel housing and bearing plate would require a lot more widening of the frame rails to install in a narrow frame Cub Cadet.

Widening the frame rails as mentioned above and then properly welding in the gussets (reinforcement angle braces) shouldn't weaken it. But make sure that the frame is in fact straight before welding in the gussets. Because sometimes it can bend during the process of widening the frame. To prevent the frame from bending overtime when doing ground-pounding wheelies, weld in the gussets on both the inside and outside of the frame. Put down a good bead of weld, too. If the frame is bent, only slightly, this will interfere with the operation and proper alignment of the clutch and driveshaft. The Cub Cadet model 147 is the only narrow frame tractor that came from the factory with widened places in the frame for the large flywheel. This is also the last narrow frame Cub Cadet manufactured before the wide frame models were produced. There's no need to widen the frame rails on a wide frame Cub Cadet (models 86, 108, 128, 800, 1000 and 1200), because the large flywheel and gear starter will clear the rails.

The parts needed to convert a K241-K341 Kohler K-series engine with a starter/generator into a gear starter are as follows:

To install a gear starter on a K241-K341 Kohler engine in a narrow frame Cub Cadet...

  1. The engine will need to be removed.
  2. The frame rails will need to be cut and widened (enough to clear the [9-1/2"] flywheel shroud), and a couple of gusset plates will need to be welded in for strength.
  3. Install the large diameter bearing plate, (9-1/2") flywheel with a starter ring gear and flywheel shroud on the engine.
  4. A gear starter motor will need to be bolted on the side of the engine block. The block will need to have an indentation for the starter.
  5. Then there's the wiring, starter solenoid and push-button starter switch that needs to be installed.

But if you prefer to use the starter/generator when pulling, remember this: the generator part require less than 1hp of engine power to charge a fully drained battery. Therefore, if you were to install an OFF/ON toggle switch to turn off the field windings in the starter/generator, this will prevent it from charging the battery. Which will allow the engine to produce more power.

After installing the flywheel shroud and if the hub adapter, flywheel or starter cup grass screen makes contact with or scrapes part of the shroud on one side. This means the big hole in the shroud is out-of-alignment with the centerline of the crankshaft. It needs to be tweaked to put it in alignment. Sometimes I have the same problem with my customer's engines. To fix it, install all the mounting bolts in the shroud, but leave them loose, then place a soft 2x4 board against the shroud, and then hit the board with a big hammer or heavy rubber hammer to force the shroud over until it's centered with the screen. This is the only way I know how to fix it. I don't know how they get out of alignment in the first place, unless it came that way from the factory and haven't been noticed before. Heck, when rebuilding and/or reassembling an engine, you tend to notice a lot of new things about it. It's kind of like painting your own house on the outside. The owner don't notice maybe a cracked window, loose siding, etc., until they get up-close with it.

Installing a 10-16hp Single Cylinder Kohler Magnum Engine in an Older Cub Cadet Garden Tractor -

With the flanges on a Kohler Magnum engine model M10, M12, M14 or M16 block cut off and with a narrow Cub Cadet oil pan installed, the Magnum will install in a spread-frame Cub Cadet with little to no modifications. But it won't fit in a narrow- or wide-frame Cub Cadet, because the Magnum flywheel shroud and bearing plate are too wide to fit between the frame rails, even when the frame rails on a narrow frame Cub Cadet are widened. Therefore, a large flywheel shroud, bearing plate and upper mount gear starter from an older K241-K341 Kohler K-series engine will need to be installed on the Magnum engine and then the Magnum should install in a narrow- or wide-frame Cub Cadet with little to no modifications.


Available Soon - Detailed Illustrated Plans on How to Construct a Professional Pull-Back and Self-Propelled Garden Tractor Pulling Sled. FYI - I have lots of work to do in my shop and I work on my sled plans in my spare time. As soon as my plans with an inventory list of parts to use are perfected, I'll post the update in my websites with prices of the plans. Remember - Perfection takes time. If it's worth having, it's worth waiting for. Also, I plan to acquire a bigger shop and may build high quality garden tractor pulling sleds in the future to offer for sale. Please call 573-256-0313 (shop) or 573-881-7229 (cell; text or voice message), or email pullingtractor@aol.com if interested in purchasing the plans or a sled. - Brian Miller


To place an order and/or for FREE professional and honest technical assistance and support, please contact: A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO (Missouri) 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell; text or when leaving a voice message, please speak slowly and clearly). Payment Options. Please call Monday-Friday, except holidays, 9am to 5pm, Central time zone. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) E-mail: pullingtractor@aol.com. A-1 Miller's shop is open to the public from 9am to 5pm, with an appointment on weekends, except holidays. Please call, text or email me before coming so I'll be at my shop waiting for your arrival. When you visit our shop, you will be dealing directly with the owner for the best customer service. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. If you're the kind of person who don't trust delivery/shipping companies (mis)handling your high-dollar and fragile merchandise, you can make the long drive to A-1 Miller's shop to personally purchase parts, or drop off and/or pick up your carburetor, clutch assembly, engine parts, entire engine, transmission, transaxle, entire garden tractor, etc. for repairing and/or rebuilding. "The road to a friend's house (or shop) is never long." (We're planning to relocate our business to other property with a bigger and better shop so we can provide many more high quality parts and professional services.) [Return To Previous Paragraph, Section or Website]

To place an order, please call the number below Ê or send an email with your name, complete and correct postal address and phone number and so I can figure the total with shipping cost and USPS Tracking. For payment options for parts ordered or services performed, or to make a donation to my websites, I accept cash (in person), USPS Postal Money Orders, cashier's checks, business checks, MasterCard, VISA, Discover, American Express (please add 2.5% to the total for the credit/debit card processor's surcharge), Western Union Money Transfer or MoneyGram Money Transfers. (If a part for a specific purpose is special ordered, your debit/credit card may be charged for the full amount or as a deposit right after your order is placed; please do not send your debit/credit card information in email!) Or you can pay A-1 Miller's through PayPal. (My PayPal account name is my email address. And be sure to mention in PayPal a description of what the payment is for.) If sending a money order, please include a note in the envelope with your name, complete and correct postal address, phone number and a description of what the payment is for. My mailing address and phone number are below Ê . I'll make a note of your order, and I may have to order some of the parts, which should take a few days to come in, but I will send the parts to you as soon as I have everything in stock after I receive your payment.

IMPORTANT - When sending your part(s) to A-1 Miller's for rebuilding or repair, package everything securely so the item(s) won't get damaged in shipping and please include a note in the box with your name, mailing address, phone number (in case I have any questions) and a description of what you want done. When shipping heavy parts, it's best to put a slightly smaller box inside a larger box, to double the strength and integrity of the package. Because the clumsy "gorillas" or incompetent and uncaring workers that work for certain delivery services mishandle the heavy packages and don't care. And when the work is completed, I'll either call or email you an invoice with the total including shipping & handling.

Payment Options and We Ship to Canada and Worldwide
Item(s) in a package or cushioned envelope weighing less than 1 lb. is sent by US Postal Service Airmail Letter Post for a 4-7 days delivery. Packaged item(s) weighing over 1 lb. and up to 66 lb. is sent by US Postal Service Airmail Parcel Post for a 4-10 days delivery. I cannot use the US Postal Services' Flat Rate Priority Mail envelopes and boxes to ship outside U.S. territories. Item(s) weighing over 67 lbs. or more is sent by FedEx Ground or equivalent services. We try to keep our shipping cost to customers within reason. Therefore, we don't ship our products in a fancy-looking package with our company name and/or logo on it because most customers will just toss it in the trash after they remove the contents. And being there is no USPS tracking number outside the US, all I can do is make sure I write your address correctly on the customs form and on your package.

My websites are not set up to process orders and accept payments. Therefore, for payment options, I accept cash (in person), USPS Postal Money Orders, cashier's checks, business checks, MasterCard, VISA, Discover, American Express (please add 2.5% to the total amount for the credit/debit card processor's surcharge), Western Union Money Transfer or MoneyGram Money Transfers. If paying with a credit/debit card, please call me at either number below. To make a payment to me through PayPal, please click this link: https://www.paypal.me/PullingTractor. Please use the "Friends and Family" option, or add 3% to the total amount to cover PayPal's processing surcharge. Or to make a payment to me (pullingtractor@aol.com) in the US through the Venmo app, please click this link: venmo.com. Or use Cash App to make a payment to me (pullingtractor@aol.com). And be sure to mention in PayPal, Venmo or Cash App a description of what the payment is for with your full name, postal address, phone number and email address. If sending a money order or cashier's check, please include a note in the envelope with your name, complete mailing address, phone number, email address and a description of what the payment is for. I'll make a note of your order when I have all your information, and I may have to order some of the parts, which should take a few days to come in, but I will send everything on your list to you as soon as I have the parts in stock after I receive your payment.



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