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Balancing a Single Cylinder Engine to Reduce Dangerous Vibration

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A-1 Miller's Fully Computerized Stuska Water Brake Dynamometer (Engine Dyno) Service!

For performance testing engines up to 200hp at speeds up to 12,000 RPM. The only engine dyno service in Missouri for Kohler pulling engines! As soon as we have this dyno set up and fully operational in our shop, every competition pulling engine that we build will be dyno-tested, fine-tuned and adjusted on our Stuska water brake dynamometer with data logger before it leaves our shop to make sure it is producing maximum horsepower and torque, or customers can rent dyno time and make adjustments or changes to their engines and print-out the results. Proposed Engine Dyno Rental Fee: $50.00 per hour run time. No setup fee for Cub Cadet engines with a 3- or 6-pin/stud clutch driver. An adapter may need to be needed or fabricated for other makes and models of engines. As soon as this service is available, it will be posted here. - Brian Miller

The basis of improved engine performance is precision workmanship. Every effort must be made to reduce friction and step up power. It must be remembered that extreme accuracy in setting the ignition timing, carburetion, together with a quality valve job, will give better than average performance. Contributing largely to stepped-up performance is precision balancing of the piston assembly and the connecting rod to the crankshaft counterweights. Special balancing equipment or an electronic digital scale is used for balancing the piston assembly/rod to the crankshaft so the total weight of the piston assembly/connecting rod is exactly the same as the crankshaft's counterweights. Also, superior balance and low vibration saves wear and tear on internal engine components and attached external equipment.

If bolts, screws or nuts on the engine or tractor frame loosen due to engine vibrations, there's no need to apply Loctite on the threads of the fastener. Just install a split lock washer of the correct size that fits the fastener (under the head or nut) then torque the fastener to specs. The lock washer will guarantee the fastener will stay tight. Or a self-locking nut can be used instead.

Here's some important information to remember -

First of all, Kohler (and all other engine manufacturers) [obviously] balance their engines at the factory. The crankshafts' counterweights are equally balanced to the weight of the piston assembly to reduce engine vibration. The crankshafts that's are used in the12hp, 14hp, 16hp [valves in block] and 18hp OHV (Over Head Valve) engines have the same stroke. The crankshaft in the 14hp and 16hp flathead cast iron block Kohler engine, and the 18hp OHV cast iron block Kohler engine are identical (except perhaps for the PTO end). Therefore, they're balanced the same and can be used in either engine. All these engines have the same stroke, too. Only the counterweights are different. More metal is removed (drilled and machined off) from the counterweights for the 12hp engines, which use a lighter weight piston. The 12hp crank and piston assembly are a balanced set. Kohler uses the same identical piston in their 16hp [valves in block] and 18hp OHV engines. Although their connecting rods are made of different material, they weigh the same. Therefore, the cranks are balanced the same. The wrist pin is narrower in the 16hp and 18hp piston, making them the same weight as the 14hp piston and pin. Therefore, the same crankshaft can be used with the 14hp, 16hp and 18hp OHV piston assembly. If both counterweights on your crankshaft aren't machined off flat, then it's a 14 or 16hp crank. If they are machined off, then it's a 12hp crankshaft. And a 12hp crank shouldn't be used with a 14 or 16hp piston assembly. The engine will vibrate more than usual and because of the heaver piston assembly, the connecting rod could stretch and eventually break. If a 14 or 16hp crank is used with a 12hp piston, because of the heavier counterweights, the crankshaft could eventually break. Because there's one opposing force working against the other. ("For every action, there's an equal and opposite reaction." - Newton's third law of motion.)

In other words, the 12hp crankshaft is balanced differently from the 14, 16hp flatheads and the 18hp OHV engine crankshafts. Although the stroke and rod journal are the same, the counterweights on the 12hp crank are different. The 12hp piston assembly weighs less than the 14, 16 and 18hp piston assemblies. Therefore, the 14, 16 and 18hp crankshafts need more metal on the counterweights to balance out equally. And 14, 16 and 18hp crankshafts are all balanced the same, which means that they're interchangeable between the 14, 16 and 18hp engines.

Because of it's shorter stroke, the 10hp crankshaft is different from the 12, 14 and 16hp flatheads and the 18hp OHV K361 cranks. The 12hp crankshaft's counterweights are machined flat for the lighter-weight 12hp piston/rings assembly, while the 14 and 16hp flatheads and the 18hp OHV K361 crankshaft's counterweights are rounded for the heavier 14 and 16hp flatheads and the 18hp OHV K361 piston/rings assemblies. The same crankshaft is used in the 14 and 16hp flatheads and the 18hp OHV K361 engines because their piston/rings assemblies weigh the same.

The diffence between the 12hp crankshaft and the 14hp and 16hp crankshafts.

There's two types of K301 12hp Kohler crankshafts. One is the early type. Its counterweights are the same width, and they're rounded with holes drilled. (Certain K241 10hp crankshafts are like this, too.) The later K301 12hp cranks have one wide and one narrow counterweight and both of them are machined flat to lighten them.

The crankshaft to the right is the very early model K301 12hp version, because the counterweights are the same width. This crankshaft was produced in 1966-early 1969, before the K321 (and the K341 and K361, which share the same crankshaft because the piston assemblies are balanced the same) came into production. The K321 went into production in late 1969. The counterweights on the crankshaft for the K321, K341 and K361 engines, one is narrow and the other is wide. When the K321, K341 and K361 engines were manufactured, Kohler stopped making this type of crank and used the K321, K341 and K361 crankshafts in the K301. They just machined part of the counterweights off and drilled a few holes to bring it into balance with the lighter weight K301 piston assembly. And I have experienced certain K301 engines vibrate severely for some unknown reason. I had to have the crankshaft dynamically and precision spin-balanced and then the engine ran smooth with a lot less vibration. This goes to show that the technology for single cylinder engine balancing during the 1960's isn't like it is today.

K-series VS Magnum Crankshafts -

A K-series 12hp crankshaft cannot be used with a 14hp, 16hp or even the 18hp OHV piston/rings assembly without adding weight to the counterweights because the 12hp crankshaft is balanced too light. The opposite would need to be done if a 14hp, 16hp or 18hp OHV crankshaft is used with a 12hp piston/rings assembly, or the engine would vibrate more than normal. If a K-series 12hp crankshaft is going to be used in a 14hp or 16hp piston assembly, it would need to precision balanced.

The Magnum crankshafts are interchangeable with the older K-series crankshafts.... but the 12hp/M12, 14hp/M14 and 16hp/M16 Magnum crankshafts are all balanced the same... for a 12hp piston/rings assembly. Some Magnum engines use three balance gears. Just like the K-series, the balance gears on the side are to reduce the side-thrust of the counterweights of the crankshaft. But the bottom balance gear in the Magnum is used to balance the rotating assembly because the Magnum counterweights are too light for the 14hp and 16hp piston/rings assemblies. Go here to learn how to align the three balance gears: Kohler Three Gear Balance Gear System Service Bulletin 208.pdf. (Requires Adobe Acrobat Reader and use Google Chrome web browser for a faster download of web sites with large files.)

For the heavier 14hp and 16hp piston/rings assemblies, the bottom balance gear simulates additional weight on the counterweights of the crankshaft so the engine will run with less vibration. If the Magnum balance gears are left out with any model, the engine will vibrate terribly! But if the balance gears are purposely left out, such as for high RPM operation, the rotating assembly would need to be precision balanced to reduce dangerous vibration. The older K-series engines will not vibrate more than it did before without balance gears installed.

And if a Magnum crankshaft is replaced with a K-series crankshaft, the Magnum balance gears shouldn't be used with the K-series crankshaft. If they are used, the engine may vibrate a lot.

If a Magnum (M12, M14 or M16) crankshaft requires three balance gears, it can be used without the balance gears in a K-series block if it is precision spin-balanced to reduce the vibration (with the connecting rod and piston/rings assembly) on a crankshaft balancing machine.

And I have no idea why Kohler changed the crankshaft balancing with the Magnum single cylinder engines to a three gear balancing system. It make no sense at all to me. I mean, the way the older K-series engines was balanced worked great. But anyway, it'll be best to leave out the balance gears and have the rotating assembly (crankshaft, piston/rod assembly) dynamically and precision spin-balanced. By having this done, the engine, with no doubt, should run much smoother and possibly last longer.

The early K-series crankshafts have a 3/16" wide slotted [flywheel] keyway and a 5/8" diameter threaded stud w/nut to retain the flywheel, and the later K-series and all Magnum crankshafts have a #5 Woodruff [flywheel] keyway and a 3/8" bolt to retain the flywheel.

The 10hp crankshaft have a shorter stroke (2.875") than the 12hp, 14hp and 16hp cranks (3.25"). The 10hp crankshaft is in a class by themselves. Therefore, they can't be used in combination with a 12hp, 14hp or 16hp connecting rod or piston assembly without extensive machine work and precision balancing. And the 12hp, 14hp and 16hp cranks can't be used with a 10hp connecting rod or piston assembly without extensive machine work and precision balancing.

Identifying the Differences in the K-series Crankshafts -

Kohler's K-series Dynamic Balance System -

Kohler's Dynamic Balance SystemSome 10hp and larger single cylinder Kohler engines use a Dynamic Balance System, which are two out-of-balance gears that rotate on stub shafts that's pressed into the PTO side of the engine block. These counter balance gears rotate in opposite direction of the crankshaft. These gears reduce the rotating side thrust (vibrating affect) of the crankshaft.

Unless a heavier crankshaft is used (than the original one that came in the engine), in some 10hp Kohler engines, it will vibrate more if the balance gears are left out. But the 12, 14, 16hp flatheads and 18hp OHV engines won't vibrate that much more without the balance gears. And the 10hp engine requires different balance gears than the 12, 14, 16hp flatheads and 18hp OHV engines.

For reasons unknown why Kohler did this, some K301 (12hp) Kohler engines will vibrate more without balance gears, while others don't vibrate much more without the balance gears. The counterweights on the crankshafts that vibrate more and the ones that don't vibrate as much look almost the same, too. Only the 12hp engines experience this. Most 14hp and 16hp engines don't vibrate much more without balance gears. Anyway, if the balance gears have been removed from a 12hp engine, and it vibrates more than before, then the Crankshaft Balance Plate Kit from Kirk Engines can be installed, or have the rotating parts (crankshaft and rod/piston assembly) precision spin-balanced at an automotive speed shop. (A place that balance race car engines.)

Don't (re)install the balance gears in an engine if it's going to turn above 4,000 RPM! (The factory maximum RPM for virtually all small gas engines, including all of Kohler engines is 3,600.) The high RPM could cause them to break and destroy the engine! So when building an engine that's going to turn above 4,000 RPM, these gears (and spacers) MUST be permanently removed! Remember - "An ounce of prevention is worth a pound of cure." It's okay to leave the stub shafts in the block. Or if you want, drive out the balance gear pins from the block (from the PTO end), cut 3/8" NPT threads and install a couple of 3/8" NPT Allen pipe plugs from outside the block. Be sure to use silicone sealer too, to prevent an oil leak. Or, the holes can be welded up solid.

And if a stock OEM-type piston assembly and connecting rod is going to be (re)used, there's no need to re-balance the crankshaft/piston/rod assembly if these gears are removed. If you want, leave the balance gears out. Actually, they're more trouble reinstalling and align with the crankshaft than they're worth. You won't notice that much difference in the vibration of the engine, either. It won't damage anything and it won't hurt anything. The engine will operate just fine without them.

By the way - I've seen balance gears in the 10hp, 12hp, 14hp and 16hp engines, but not every one of them have balance gears. I've even seen some 16hp Kohler Magnum engines have three balance gears! Anyway, it seems that Kohler was selective in which engines they put them in. Perhaps they only put them in engines that was installed in a "luxury-type" of garden tractor to help reduce operator discomfort. And every balance gear I've ever seen appear to be exactly the same weight and design.

For most single cylinder Kohler engines, balance gears isn't necessary.

Leaving out the balance gears shouldn't have a noticeable effect on engine vibration, but sometimes they help to reduce engine vibrations. So if you choose to reinstall or leave them in an engine that will never turn more than 4,000 RPM (this is the maximum RPM for pulling in stock classes or doing ordinary yard work), make sure that the bearings in the [balance] gears and the stub shafts that they spin on are in good condition. If the bearings are worn and if the balance gears wobble, they'll wear the crankshaft gear teeth and they could break, possibly destroying the engine. By the way - the balance gears alignment tool (timing gage) is no longer available from Kohler. If you find a good used one or a new one from a Kohler dealer's old stock, the Kohler part numbers are 25 455 06-S, 10355 or Y-357. It's much easier to use this plastic tool when aligning the balance gears in time with the crankshaft. See the animated image to the right for correct identification of this tool.

Once, just for curiosity, after I've rebuilt a 12hp (K301) Kohler engine, I've ran the engine with the balance gears installed and correctly aligned with the crankshaft. Then I removed the balance gears just to see if the engine would vibrate more. (It wasn't a lot of work to remove the gears. I removed the oil pan, snap rings, washers and spacers, rotated the crankshaft to clear the balance gears, and lifted the gears right out.) Anyway, I found that without the balance gears, the engine vibrated EXACTLY the same as when the gears were installed! Wonder why Kohler installs them in the first place. ????

The balance gears in a 12hp Kohler engine can be removed without removing the crankshaft. What's needed is a heavy duty snap ring pliers with 90º tips to remove the [heavy gauge] snap rings. Be sure to remove the spacers (if equipped) and shims from the shafts, too. The counterweights on the 12hp crankshaft are machined off, allowing room to remove the balance gears. But on a 14 and 16hp engine, one of the counterweights on the crankshaft may be in the way. If it is, try driving the pins into the crankcase from outside the PTO end of the block then plug the holes from the outside with a couple of 1/2" cup-shaped expansion plugs or cut threads for a couple of 1/4" NPT Allen pipe plugs. By the way - the shims from removal of the balance gears can be used as camshaft shims to set the cam-to-block clearance on the 10-16hp engines.

Use quality snap ring pliers with 90° tips to remove the snap rings that retain the balance gears. Because these snap rings are actually thicker than ordinary ones which makes them harder to expand. A flat screwdriver may need to be wedged under each snap ring to help them off the stub shafts. (Been there, done that many times. And it's difficult each time.)

How To Remove the Crankshaft from a Kohler Engine -

Remove the piston/connecting rod, flywheel, bearing plate and anything that's on the PTO end of the crankshaft. (Not necessarily in this order.) Then very gently, bump the PTO end with a wooden block to remove the crankshaft from the block. And there's no need to reinstall the balance gears. They serve very little purpose.

How Fast Can You Spin A Cast Iron Crankshaft?

As long as the piston assembly and connecting rod to the crankshaft counterweights, including the flywheel, starter pulley and clutch components are all precision balanced, you can spin it as fast as you want. Just make sure to have the crankshaft checked for stress cracks (magnafluxed) before using it.

When installing a high-performance [heavier than OEM stock] piston and connecting rod assembly in a single cylinder engine, and to minimize dangerous vibration and to prevent the possibility of self destruction, the crankshaft must be re-balanced (more weight added to the counterweights) to compensate for the difference in weight. If an engine vibrates severely, then the only things that causes the vibration is the piston/rings/wrist pin/clips assembly and/or the connecting rod isn't equally balanced to the crankshaft's counterweights. Another thing would be an out of balance flywheel. Also, if there's a parasitic accessory attached to the crankshaft, such as a bent pulley, it could be causing the vibration.

Note: when using an OEM piston assembly and connecting rod, and if the rod journal (crank pin) on the crankshaft is reground for a smaller diameter bearing, that will not throw off the balance of the rotating assembly. Because the undersized rod bearing will take up the material that was removed from the crankshaft.

FYI - STATIC balancing is when parts are at rest, and DYNAMIC balancing is when parts are in motion. Dynamic balancing is a more precise way to balance anything that spins, but static balancing is a lower cost alternative... also proven very effective. An accurate and precision electronic digital scale that breaks at 1/10th of an ounce (0.1 lb.) or 1 gram to static balance a crankshaft to the piston and connecting rod assembly will be needed. For an example of how much 1/10th of an ounce is, a dime (10¢) weighs exactly 1/10th of an ounce (or 2 grams).

How to Static Balance a Single Cylinder Engine:

  1. Precision Electronic Digital ScaleAcquire a precision electronic digital scale that can weigh up to around 13 lbs., and one that breaks at 1/10th of an ounce (0.1 lb.) or 1 gram. An electronic digital scale is more precise for balancing an engine than a mechanical one. And the higher the capacity of a scale, the less precise it will be. An accurate and precision balance beam scale can be used to weigh the differences between the stock piston/rod assembly and the high performance piston/rod assembly.
  2. Use pencil, paper and arithmetic for this procedure, to make a note of the results. Pencil and Paper
  3. Weigh the stock (preferably std size) piston, rings, pin, clips and connecting rod as a unit. Make a note of the total weight. Be sure the scale is on a flat, level surface. If it's not, an inaccurate reading will result. Weigh the piston, rings, wrist pin, clips and connecting rod that originally came with the crankshaft. If you don't have the original piston/rod assembly, here's the approximate weights for them: The stock OEM 12hp (K301) piston assembly and rod weighs 29.1 ounces or 823 grams. And the stock OEM 14hp (K321) and 16hp (K341) piston assembly and rod weighs 31.4 ounces or 891 grams.
  4. Now weigh the high-performance/aftermarket piston, rings, pin, clips, connecting rod and bearing insert as a unit. Make a note of that weight.
  5. Subtract the two above È weights and make a note of the difference.
  6. Now weigh the crankshaft that was originally used with the stock OEM piston/rod assembly. Make a note of that weight. The average weight of a typical cast iron Kohler 12hp (K-301) crankshaft with a 1" diameter x 3" long PTO end is 151 oz. or 4,280 grams. And the average weight of a typical 14hp (K-321) and 16hp/18hp (K-341/361) crankshaft with a 1-1/8" diameter x 3" long PTO end is 158.2 oz. or 4,485 grams. Remember that the weight of every crankshaft will vary a few ounces depending on the length and diameter of the PTO end, if the PTO end has a drilled and threaded bolt hole, or if the flywheel end has a 3/8" threaded bolt hole or a 5/8" or 3/4" diameter stud. (These numbers are for reference only.)
  7. Add the difference in weight of the two piston/rod assemblies above È to the crankshaft counterweights. Drill holes lengthways in the counterweights and weld in some heavy metal (tungsten steel), or fill in the factory drilled out holes with some lead capped with steel that's held in place with a roll pin driven in crossways, or weld or bolt some thin plate steel on the side(s) of the counterweights, etc. NOTE: Try to add an equal amount of weight to each counterweight so the crankshaft won't it be too heavy on either end. Not doing this may result in crankshaft breakage over time. And remember, crankshaft breakage could destroy other internal parts of an engine as well!
    It must be a high-quality welding job whenever any welding is done on a cast iron crankshaft! Remember, cast iron is porous and absorbs oil. This means the counterweights must be thoroughly heated with an acetylene torch or the crank placed in a special oven furnace and rotated it against large flames to burn the oil out of the metal, then it'll be good for welding.
  8. Weigh the crankshaft again and subtract the difference from the result that was derived in step 4.
  9. The added weight to the crankshaft should now reflect the difference in weight of the two piston/rod assemblies. If it doesn't, it's OK to grind off some weight from the counterweights.
  10. That's it! The crankshaft and piston/connecting rod assembly are now statically balanced. On the average, about 160 grams or 5.64 ounces of weight is added to the counterweights on a Kohler crankshaft to precision balance it for a stock connecting rod and piston/rings assembly.

If a high-performance 12hp (K301) piston assembly is going to be used in a Kohler engine, a 16hp or 18hp crankshaft can be used instead for rebalancing. Less weight will need to be added to the counterweights because of the smaller and lighter weight 12hp piston assembly.

Heavy metal (tungsten steel) and tools that's specifically made for crankshaft balancing can be purchased from GOODSON ( Tools and Supplies for Engine Builders. (Request a catalog from them.)

The reason most [high dollar] billet steel crankshafts break at wide open throttle is because they were not dynamically and precision spin-balanced using a specialized crankshaft/flywheel balancing machine. This happens when the counterweights on the crankshaft weighs much more than the piston and connecting rod assembly. When out-of-balance, the crankshaft flexes a few thousandths of an inch at high RPMs, which weakens the metal and causes fatigue cracks, eventually resulting in breakage. When a crankshaft breaks, it can destroy the camshaft and possibly the engine block. So it's very important that an aftermarket billet steel (and cast iron) crankshaft be dynamically and precision spin-balanced when the engine is ran at very high RPMs. Most manufacturers of billet steel crankshafts do not dynamically and precision spin-balance them. They include counterweights on the crankshaft that's pre-weighed and matched to the weight of the piston and connecting rod assembly to be used with the crankshaft. The counterweights must weigh the same as the piston and connecting rod assembly, with the exception of the weight of the rod journal, which counter-weighs the counterweights. When rotating, the rod journal too, adds weight to the piston and connecting rod assembly. And the same balancing machine that's designed to balance automotive crankshafts and flywheels can be used to balance single cylinder Kohler (and other makes of small engines) crankshafts and flywheels. To balance a crankshaft with a specialized flywheel/crankshaft balancing machine, all that is needed is a bob-weight that clamps on the rod journal. The bob-weight simulates the weight of (and must weigh exactly the same as) the piston and connecting rod assembly that is going to be used with the crankshaft to be balanced. If the piston and connecting rod assembly and/or crankshaft is used with another piston and connecting rod assembly and/or crankshaft, the rotating assembly will be out-of-balance.

But then again, when excessively out of balance, a billet steel crankshaft will not always break. A billet connecting rod will break instead. This happens when the piston and rod assembly weighs much more than the counterweights on the crankshaft. What happens is, as the engine rotates at high RPMs or at wide open throttle, the weight of the piston and connecting rod is sent upward a lot more than the counterweights are sent downward , resulting in two unequal opposing forces, and this places severe strain on the connecting rod cap' bolts. Eventually, the upward force of the piston and rod will cause the bolts to stretch (the 4-bolt hex socket (Allen) head cap screws (bolts) in certain billet rods are more prone to stretching), which will cause the rod to knock, and the continuing stretching of the bolts will cause them to break, ultimately resulting in connecting rod breakage, which can destroy the entire engine block. So it'll be a good idea to definitely spend the extra time and money to have your rotating assembly dynamically and precision spin-balanced.

Click here to see what can happen to an unaltered 9-1/2" diameter cast iron Kohler flywheel when spun well above 4,000 RPM.

If the engine still vibrates at high RPM or at wide open throttle after doing the above È, it's either because of the side thrust of the crankshaft counterweights (which is normal in single cylinder engines), or if the vibration is severe, have the flywheel checked for precision balance and/or the clutch assembly trued up in a metal lathe. If you have a garden tractor with rubber motor mounts, these must replaced with solid metal mounts. If the crankshaft/piston/rod are balanced correctly and the flywheel is also balanced, and the tapers are clean, the crankshaft should last the life of the engine. Even when used in high-performance conditions.

If you need any of the parts or services listed below Ê, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell). 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.) 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. Fax: 1-573-449-7347. E-mail: 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. NOTE: To place an order, please call either number above or send an email with a list and description of the parts or services you need. Because as of right now, my websites are not set up to accept orders online.
High Quality Wireless Tachometer. For gas engines only. 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 governored engines at pulling events. Hold close to the spark plug wire for reading. Operates off a self-contained 9 volt battery. Reads up to 5,000 RPM on the low scale, and 15,000 RPM on the high scale. Very accurate.
  • $85.00 each, plus shipping & handling.
Tachometer/Proximity Sensor Kit. For gas or diesel engines. This digital tach setup is triggered by the same method as the Dynatek and Pertronix crank trigger ignition systems just below Ê, with a small detector magnet embedded in an aluminum trigger rotor on the crankshaft. When ordering, please specify diameter of crankshaft PTO end for trigger rotor. Most common crankshaft PTO end diameters are 1" and 1-1/8", but 1-1/4" and 1-7/16" are rare. And most steel crankshafts have a 1-1/2" diameter PTO end. Trigger rotor measures 2-1/4" diameter x 1/2" wide, and comes with countersunk/embedded magnet and Allen set screw. Sensor mounts in supplied angle bracket that fastens on PTO end of engine block. Display can be dash-mounted in a garden tractor. Can operate off a remote 9 volt battery, but works best with 12 volts. Displays up to 9,999 RPM. Very accurate.
  • Complete Kit. $80.00 each, plus shipping & handling.
Solid Motor Mounts for Cub Cadet "Quiet Line" Tractors - Replace Deteriorated ISO-Mounts with a Set of Machined Solid Steel Motor Mounts! An innovative concept by Brian Miller, because I was the one who originally thought of and advertised this product.

Details include:

  • An alternative to the deteriorated OEM "ISO" rubber engine mounts. Fits Cub Cadet "Quiet Line" models 680, 800, 1000, 1200, 1210, 1250, 1282, 1450 and 1650. If your tractor has two angled brackets that attach to the engine, with rubber mounts between the brackets and the frame, then these are what you need.
  • A MUST for competitive pulling or everyday use because they stabilize the engine to prevent severe engine vibration at high RPM or at wide open throttle, and they save wear on the clutch/driveshaft components, especially the flexible 3-pin clutch drive plate.
  • For competition pulling, heavy towing, garden plowing, pushing snow, yard work or just lawn mowing.
  • Direct replacement - replaces the entire rubber mounts. They install between the tractor frame and engine mounting brackets. A flat washer fastens on top of the brackets. Machined so they set the engine height at the correct alignment with the driveshaft.
  • By the way - rubber motor mounts are intended for operator comfort from engine vibration only. The ISO-mount tractors with solid motor mounts installed would feel and operate just like the older models with a solid mounted engine. And some people use my solid motor mounts just to mow grass and tell me that the mounts don't cause their tractor to vibrate much at all. But others have used them and said the vibration was unbearable. In this case, the engine should be dynamically and precision spin-balanced. So all I can say is try them. If you don't like them, return them for a full refund less shipping and handling. Or to minimize the vibration, either have the rotating engine parts dynamically and precision spin-balanced, or install a set of rubber mounts. And the welded enforcement cross bar is required only with rubber ISO mounts. There's no need for it with solid motor mounts.
  • Can be easily removed if rubber mounts are used instead. If you'd prefer to use new rubber motor mounts, you can install an OEM Cub Cadet ISO mount kit, part # 759-3952, or visit your nearest NAPA auto parts store. They have a variety of rubber mounts. Some shock absorber mounts are the same thing.
  • Weighs about 4 ounces each.
    • Solid mounts only (no bolts or washers). $30.00 per set of four, plus shipping & handling.
    • Solid mounts with mounting hardware (grade 8 bolts/nuts/lock washers/thick flat washers). $40.00 per set of four plus shipping & handling.
Used 9-1/2" diameter genuine OEM cast iron Kohler K-series flywheel for 10hp-16hp K-series flathead and 18hp OHV engines. These flywheels are for battery ignition only, not magneto ignition. They're in excellent condition and unaltered. No crack in the keyway, no broken or missing fan blades and no cracked or missing internal magnets for charging system (if used for yard use). These flywheels are for stock tractors only; not to be turned above 4,000 RPM!
  • Flywheel with ring gear and internal charging magnets. $125.00 each, shipping included within in the Continental U.S. if purchased separately.
  • Flywheel without ring gear (install your own ring gear) and with or without internal charging magnets. $85.00 each, shipping included within in the Continental U.S. if purchased separately.
  • Flywheel without ring gear (install your own ring gear) and majority of fan blades removed and precision balanced and with or without internal charging magnets. $115.00 each, shipping included within in the Continental U.S. if purchased separately. (Click on picture to the right for a larger view.)
  • Flywheel with ring gear and majority of fan blades removed and precision balanced and with or without internal charging magnets. $135.00 each, shipping included within in the Continental U.S. if purchased separately. (Click picture below for a larger view.)
  • Used ring gear. $25.00 each, plus shipping & handling.
  • Your flywheel - remove majority of fan blades and precision rebalance. $85.00 labor, return shipping extra. Includes cutting most of the fan blades off, chuck it in our lathe to true up the fan blades so they're all even and then balancing it.
10hp, 12hp, 14hp and 16hp K-series and Magnum flathead single cylinder engine crankshafts. These cast iron cranks are a genuine Kohler part, they're used, but in good condition. They may have either a 1" or 1-1/8" diameter x 3-1/2" long keyed PTO shaft and may have a STD or freshly reground .010", .020" or .030" undersized journal. Although .030" is rare, it's still safe to use. And if you're going to use a pulley, clutch, etc., on the PTO end, then I need to know the dimensions of the PTO shaft on your crankshaft so we can match it to one that we may have in stock. Measure the diameter and length from the gear teeth. [When available.]
  • 10hp (K241/M10) $100.00 each, plus shipping & handling.
  • 12hp (K301/M12) $150.00 each, plus shipping & handling.
  • 14hp (K321/M14), 16hp (K341/M16) and 18hp (K361) $125.00 each, plus shipping & handling.
Flywheel and Crankshaft Precision and Dynamic Spin-Balancing Service. To balance the rotating assembly, the crankshaft, piston/rings, pin, clips, connecting rod and bearing inserts (if applicable) are all required. The flywheel is balanced separately.
  • Balance (cast or steel) flywheel for Kohler 10-16hp cast iron block engine. $60.00 labor, plus return shipping & handling.
  • Balance flywheel for other make and model of engine. I will need to make a spindle with a tapered end/bolt hole to match the taper in the flywheel to spin the flywheel. $85.00 labor, plus return shipping & handling.
  • Balance single cylinder OEM Kohler cast iron crankshaft. $200.00 for welded weight plate and labor, plus return shipping & handling.
  • Balance single cylinder billet steel crankshaft. $300.00 for drilling length-ways through rod journal, welded weight plates and labor, plus return shipping & handling.
  • NOTE: Usually, a steel plate (of various thicknesses) is welded on the side of the counterweight that's next to the gear on the crankshaft to balance it. This is the easiest way to balance a Kohler crankshaft. But on other makes of crankshafts where there's no room for the balance plate, holes would need to be drilled crossways through the counterweights, and tungsten steel plugs will need to be welded in the holes. To do this, the price will be around $400.00 per crankshaft, plus return shipping & handling.

IMPORTANT - When sending your flywheel and/or rotating assembly to me for balancing, package everything securely so the items 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 place a slightly smaller box inside a larger box, to double the strength and integrity of the package. Because some "gorillas" that work for certain delivery services don't care. And when the work is completed, I'll either call or email you an invoice with the total including shipping & handling.

Flywheel Retaining NutAll-metal self-locking flywheel retaining nuts for threaded stud on end of K-series and steel crankshafts. Guaranteed to stay tight! IMPORTANT: Apply thin coat of motor oil on threads of crankshaft before installing nut then torque each at 65 ft. lbs.
  • 5/8" diameter, fine thread (5/8-18 UNF). Replaces Kohler part #'s 25 100 02-S, X-119-14. (Discontinued from Kohler.) $1.50 each, plus shipping & handling.
  • 3/4" diameter, fine thread (3/4-16 UNF). Replaces Kohler part #'s X-89-11, X-119-16. (Discontinued from Kohler.) $1.75 each, plus shipping & handling.
Flywheel retaining bolt for threaded hole in end of crankshaft. Each are grade 8, 1-1/2" thread length. Torque at 40 ft. lb. Replaces Kohler part # 25 086 253-S.
  • 3/8" diameter, fine thread (3/8-24 UNF). $1.00 each, plus shipping & handling.

OEM Kohler Aluminum Clutch Hub Adapters. Fits John Deere and all models of Cub Cadet garden tractors.

  • Hub adapter w/5/8" hole and pulley. Used and in excellent condition. No longer available from Kohler. OEM Kohler part # 41 071 01. $40.00 each, plus shipping & handling.
  • Hub adapter w/3/8" hole. Used and in excellent condition. No longer available from Kohler. OEM Kohler part # 52 071 02-S. $40.00 each, plus shipping & handling.
  • Hub adapter w/5/8" hole. Used and in excellent condition. $40.00 each, plus shipping & handling.
  • Hub adapter w/5/8" hole. New. OEM Kohler part # 41 071 03-S. $88.10 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 vibrations, 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.
New main crankshaft bearings for 7hp and 8hp Kohler K-series and Magnum single cylinder cast iron flathead engines. These are specifically designed to provide maximum performance by means of precise ball implement selection. Heat treated. Made in China, but has the same quality as OEM Kohler bearings for long wear. Dimensions: 1.18" i.d. x 2.44" o.d. x .62" width. Part # 150-960. $10.00 each, plus shipping & handling.
New 8 ball main crankshaft bearings for 10hp, 12hp, 14hp, 16hp (flatheads) and 18hp (OHV) Kohler K-series and Magnum single cylinder cast iron engines. These are specifically designed to provide maximum performance through precise ball implement selection. At high RPM or at wide open throttle, bigger balls run cooler which create less rolling resistance than bearings with smaller balls. Heat treated. Made in China, but has the same quality as OEM Kohler bearings for long wear. Dimensions: 1.57" i.d. x 3.54" o.d. x .90" width. Part #150-973. $15.00 each, plus shipping & handling.
NOTE: If you cleaned all the oil out of the crankshaft main [ball] bearings and allowed them to dry, and when you spun the bearings by hand, and if the bearings isn't worn much or at all, they might feel "rough" and make a rattling sound. This roughness or noise isn't necessarily because the bearing is worn out. The noise is mainly caused by the balls running dry on the races because there's no oil to separate them from the races. Try applying a small amount of motor oil to the balls/races then spin them. They should be a lot quieter. The same thing will happen with new ball bearings.
Balance Gears to convert ordinary Kohler K-series or Magnum engine models K241/M10 (10hp), K301/M12 (12hp), K321/M14 (14hp), K341/M16 (16hp) or K361 (18hp OHV) to Dynamic Balance. NOTE: Two 1/2" factory drilled holes MUST be present in the block for these to work!

Complete Kit (Includes two balance gears, two stub shafts, two spacers, four shims and two snap rings.)

  • Used parts. $80.00 per kit, plus shipping & handling. (When available.)
  • New parts. $326.70 per kit, plus shipping & handling.

Balance Gears. OEM Kohler part # 45 043 03-S.

  • Used and in excellent condition. $20.00 each, plus shipping & handling. (When available.)
  • New. $107.15 each, plus shipping & handling.

Heavy Duty Snap Ring for Retaining Balance Gears. Thicker metal than ordinary snap rings for durability. OEM Kohler part # X-269-34-S.

  • $1.75 each, plus shipping & handling.

Balance Gear Spacer, Shim and Snap Ring Kits. (Includes one of each for one balance gear.) OEM Kohler part # 47 755 01-S.

  • Used and in excellent condition. $10.00 per kit, plus shipping & handling. (When available.)
  • New. $37.20 per kit, plus shipping & handling.

Needle Bearings for Balance Gears or for a Steel Cam that require them. Dimensions: 1/2" (.500") i.d. x 11/16" (.6875") o.d.

  • High quality aftermarket. Our part # 116457. $10.00 each, plus shipping & handling.
  • OEM Kohler part # 236506-S. $43.95 each, plus shipping & handling.

Balance Gear Stub Shafts. OEM Kohler part # 236559-S.

  • Used and in excellent condition. $10.00 each, plus shipping & handling. (When available.)
  • New. $37.20 each, plus shipping & handling.

A-1 Miller's Performance Enterprises Offering Quality Products and Professional Workmanship at Reasonable Prices!

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