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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 -
Kohler [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.
Actually, there's two kinds of 12hp Kohler crankshafts. One is with one wide and one narrow counterweight and both counterweights are machined off. The other, which is rare, the counterweights are the same width, and they're rounded with holes drilled. Some 10hp crankshafts are like this, too.
A 12hp crankshaft cannot be used with a 14hp, 16hp or 18hp OHV piston 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 in a 12hp block, or the engine would vibrate more than normal. The Magnum crankshafts are interchangeable with the older K-series crankshafts... as long as a 12hp piston assembly is used. But if the crankshaft is going to be used in a 14hp or 16hp piston assembly, it would need to dynamically balanced. Click here to read more about this. By the way - the only major differences between the older K-series and the newer Magnum crankshafts are where the flywheel fastens onto. The K-series have a 5/8" diameter threaded stud and the Magnums have a 3/8" threaded bolt hole.
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 Kohler Crankshafts -
Kohler's 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 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.
Don't (re)install the balance gears in an engine if it's going to turn above
4,000 rpm! (The factory maximum rpms for virtually all small gas engines,
including all of Kohler engines is 3,600.) The high rpms 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
rpms (this is the maximum rpms 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 I took them out to see if the engine would vibrate more. (It wasn't a lot of work to remove the gears. I just removed the oil pan, snap rings, washers and spacers, rotated the crankshaft a certain way, and then 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! 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.
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 (.001 lb.) or 1/2 of a gram to static balance
a crankshaft to the piston and connecting rod assembly will be needed.
For an idea of how much a gram weighs,
a dime (10¢) weighs 2 grams.
How to Static Balance a Single Cylinder Engine:
Acquire
a precision electronic digital scale that can weigh up to about 13 lbs.,
and one that will break at 1/10th of an ounce (.001 lb.) or 1/2 of a gram.
A digital scale works much better for balancing an engine than a mechanical
one. And the higher the capacity, the less precise it will be. The more precise
it is, the better. Look on
eBay for a quality digital scale.
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 (it actually soaks up oil).
This mean you must first heat the counterweights with an acetylene torch
to burn the oil out of the metal. Then it'll be good for
welding.
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 your crankshaft and piston/rod assembly and/or flywheel
precision dynamically balanced, please contact me, Brian Miller, at
A-1 Miller's Small Engine & Specialty Shop
(1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033).
Please call any day between 12 noon and 8:00 p.m. Central time, and please
be patient because I stutter. | Fax: 1-573-449-7347. You can also contact
me through Yahoo! Messenger:
Balancing Service -
You can also have your flywheel and crankshaft/piston/rod assembly professionally dynamically precision balanced at:
|
If you're looking for a steel crankshaft, aftermarket connecting rod or other engine parts, look in my advertisement web site or you can place a want ad in the same site.
Advertisement:
| If you need a set of solid motor mounts, please contact me, Brian
Miller, at A-1 Miller's Small Engine & Specialty
Shop (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone:
1-573-875-4033). Please call any day between 12 noon and 8:00 p.m. Central
time, and please be patient because I stutter. | Fax: 1-573-449-7347. You
can also contact me through Yahoo! Messenger:
|
| Replace Deteriorated ISO-Mounts with a set of my Machined Solid
Steel Motor Mounts -
|
Advertisement:
| If you need any of the items below, please contact me,
Brian Miller, at A-1 Miller's Small Engine & Specialty
Shop (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone:
1-573-875-4033). Please call any day between 12 noon and 8:00 p.m. Central
time, and please be patient because I stutter. | Fax: 1-573-449-7347. You
can also contact me through Yahoo! Messenger:
|
||
10hp, 12hp,
14hp and 16hp K-series and Magnum flathead engine crankshafts. These cast
iron cranks are a genuine Kohler part, in good condition, with good keyways.
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. $85.00 each, shipping
included. [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. |
![]() 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. |
![]() 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. NOTE: I can also custom machine other adapter washers to fit your particular application. All I need is the dimensions. $10.00 each, plus shipping. |
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.
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 rpms, 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. 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!
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. (When available.) |
||
Linked pages to my parts & services:
Please click HERE, e-mail me at
pullingtractor@aol.com or call
me at 1-573-875-4033 if you need various parts, machine work performed, repairs
made, if your business would like to help sponsor my web sites or if you'd
like to make a small donation toward my web sites. Please call between 12
noon and 8:00 p.m. Central time, and please be patient talking with me on
the phone because I stutter. You can also contact me through Yahoo! Messenger:
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