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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 (like the one pictured in this web site) 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.
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.
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.
There's two kinds of 12hp K301 Kohler crankshafts. One is the early type. Its counterweights are the same width, and they're rounded with holes drilled. (Some 10hp crankshafts are like this, too.) The newer 12hp K301 cranks have one wide and one narrow counterweight and both of them are machined flat to lighten them.
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.
For the heavier 14hp & 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.
The early K-series crankshafts have a 5/8" diameter threaded stud to retain the flywheel, and the later model K-series and all Magnum crankshafts have 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 -
Some 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 http://www.kirkengines.com/index.php#CrankshaftBalancePlateKit 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 1/4" NPT threads and install a couple of 1/4" 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 really necessary.
Leaving them out shouldn't have a noticeable effect on engine vibrations, but they do help to reduce engine vibrations somewhat. 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 - you can get the balance gears alignment tool (timing gage) from your local Kohler engine dealer. The part number is 10355 or Y-357. It's much easier to use this tool when aligning the balance gears in time with the crankshaft. See the drawing 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. Then we took them out to see if the engine would vibrate more. (It wasn't a lot of work to remove the gears. WE just removed the oil pan, snap rings, washers and spacers, rotated the crankshaft a certain way, and then lifted the gears right out.) Anyway, we found that without the balance gears, the engine vibrated EXACTLY the same as when the gears were installed! Makes ya 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 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, the counterweights may be in the way. If it is, try driving the pins from the PTO end of the block instead and 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.
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.) And 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.
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.
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.
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 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 idea 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:
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 (http://www.goodson.com) Tools and Supplies for Engine Builders. (Request a catalog from them.)
An aftermarket steel crankshaft will need to be dynamically spin-balanced in a precision balancing machine if nothing has been balanced to it before. And the same balancing machine for automotive engines [and flywheels] can be used to balance single cylinder Kohler engines. All that is needed is a bob-weight that clamps to the crank journal. Also, the same balancing machine for automotive engines can be used to balance Kohler flywheels. 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 after doing the above, 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 below, please contact A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO 65203-9136 USA | Phone: 1-573-875-4033. Please call Monday-Friday, 9am to 5pm, Central time. If no answer, please try again later. (When speaking with Brian, please be patient because I stutter.) Fax: 1-573-449-7347. E-mail: firstname.lastname@example.org. You can also contact us through Yahoo! Messenger: Find us here: Directions to our shop | Yahoo! Maps, 1501 W. Old Plank Rd., Columbia, MO | 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 or send an email with a description of the parts or services you need. Because as of right now, we're not set up to accept orders through our web sites.|
|For Cub Cadets - Replace Deteriorated ISO-Mounts with
a Set of Machined Solid Steel Motor Mounts -
|For Wheel Horse - Replace Deteriorated ISO-Mounts with
a Set of Machined Solid Steel Motor Mounts -
|Balancing Service -
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.]
Flywheel retaining nut for older K-series crankshaft stud. 5/8-18 NF threads. Self-tightening jam nut. Torques at 65 ft. lbs. $1.00 each, plus shipping & handling.
Flat washer for retaining flywheel and/or aluminum clutch hub adapter to flywheel. A must to secure flywheel and to prevent hub breakage! 41/64' i.d. x 1-1/4" o.d. x approximately 1/4" thick. $2.00 each, plus shipping & handling.
|Steel adapter step-washer
for mounting the aluminum clutch hub with a 5/8" hole to the Kohler Magnum
crankshaft with a 3/8" bolt. A must to prevent hub breakage! $8.00
each, plus shipping & handling.
NOTE: We can also custom machine other adapter washers to fit your particular application. All we need are the dimensions. $10.00 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 higher rpm, 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 then allowed them to dry, and then later 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 and then spin them. They should be a lot quieter. The same thing will happen with new ball bearings.
|For die-hard believers in balance gears!
Used 12hp, 14hp and 16hp balance gears with good, snug bearing. $10.00 per pair, plus shipping & handling. (When available.)
Complete kit (balance gears, stub shafts, shims and snap rings) to convert an ordinary Kohler K-series and Magnum 10hp, 12hp, 14hp, 16hp (flatheads) and 18hp (OHV) single cylinder cast iron engines to Dynamic Balance. The two holes MUST be present in the block for this to work! $30.00, plus shipping & handling. (When available.)
Linked pages to our parts & services:
A-1 Miller's Performance
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