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MikeES

Odd Kohler

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MikeES
Here is one for the Kohler know-it-all. I have a Kohler engine that the stickers say is a K241 (10hp). The bore and stroke measure 3.250 x 2.875. Just what the book says it should measure. The piston is marked .010 The casting in the block is K301 (12hp). The height of the block is the same as my other K301. What do I have here? How does a .010 piston fit into a std. bore? Has anyone else run into a 10hp bore and stroke in a K301 casting?

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Chris727
Hi. This will not help with the piston issue but I believe the 10hp and 12hp K-Series kohlers used basically the same block with a different bore size. The 10's with the K301 on the block casting can be bored out to the 12hp bore. Not all of the K241's are like this. Only the ones with the K301 stamp. My AC 710 has the original 10hp engine but has a K301 stamp on it. I know a Cub collector (one of those Kohler guys!. He is always looking for the K241's with the K301 stamp because he can rebuild them as 12's.

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firefoxz1
I don't know if this will help but here it is, It looks like with just .002 inches of wear in a cyl a .010 would fit in but once the engine got hot it would probably expand and lock fast to the cyl wall. http://www.yetmans.mb.ca/kohler/page4_5/page4_5.html

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TimJr
I also know that the typical 12hp is the same block as a 14hp Kohler. Only the bore is smaller on the 12. Bore it out, and stick in the 14hp piston. Or you could look at it that the 12 hp block could be rebuilt/rebored 7 times using the factory pistons for the 12hp oversizes, then the 14hp and its oversizes. Seems like that there are 14hp engines with a K301 stamping on it. Not to mention the Kohlers that came with a .003 oversize piston from the factory - I've got one. They were basically out of spec, but instead of scrapping it, they finished the bore out .003, then hand stamped the top of the deck +.003". Then there are the 16hp - I understand there are at least 3 different blocks, and one is pretty valuable to tractor pullers because it is supposedly much stronger - maybe check out Midwest Cubs website - they specialize in Cub pulling. Tim

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MikeES
Thanks. As a puller I know about the 16 hp, 16 fin Kohler engines. This 10hp has no ring ridge so it has no wear but it burns oil like crazy. You can run the engine (runs great) pull the head, and the head, valves, piston and cylinder is just coated with oil (yes the breather is working correctly). I have ordered .010 over rings and plan to install them next week. But now after taking closer measurements, I am concerned that I will have problems, like firefox pointed out. I have not pulled the piston out yet. Mike S

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BLT
You don't have an oil control ring in there upside down, do you? That would answer your oil burn. After looking at the std bore dimensions in the Kolher book, I don't see how something could get screwed up. Each bore is a minimum of .125" away from another. You can't sastify the numbers with an .010 oversize piston from something else.

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B.Ikard
Be careful with all the boring/switching of parts. They look the same but they are not. I went thru all this on my 7012/7014 that I built and researched/planned till my head hurt:). The 12hp block will not be reliable bored to 3.500 as the cylinder walls will be thin as paper. You will need a 14hp 321 block if you plan to do this. Also the crankshafts are different with regards to balance. The 12 crank has machined flats on the counterweights, some 14's do and some don't and the 16's have no machining. Wrong crank/piston combination and you will vibrate and wear. The 10/12 and small exhaust valve 14's use a smaller venturi carb than the later 14's and 16's too. This is a good Kohler website http://members.aol.com/pullingtractor/engine.htm Ike

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MikeES
Update - I pulled the piston and the compression rings look OK but the oil rings were not moving and compressed tight into the piston (that explains the oil burning). The piston dia. measures 3.225 which is smaller than the stock diameter (according to the book 3.243). Remember the piston is marked .010 on the top. The piston has very little wear, the whole engine is like new. Does this thing have the wrong piston in it? If it is what would this piston fit? Any other ideas or comments are welcome. Thanks, Mike

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Roy
Mike, I do not know the numbers but measure the piston across the wide section (pistons are supposed to be elliptical) and measure the bore. There is a specification for the piston-to-bore clearance. If the piston and bore you have fall within that specification the piston should be OK to use. If the piston diameter falls outside the clearance range you can calculate the required piston size and/or bore size to fit the piston size you have. You can also put the piston in the bore and use a feeler gauge to check the clearance. Either way the fit must fall within the specification. Same thing for the rings when you get them. Put them in bore and check the end gap clearance. Proper size rings will have an end gap that falls into the acceptable specification range. If this is "old hat" to you let me know and I'll be quiet. Otherwise, maybe it will help. Good luck,

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comet66
Just by way of informetion...I picked up a newly rebuilt 289 about 10 years ago, that pushed oil at higher RPM's. What I found was the rings on two pistons were perfectly lined up. Just a thought about something else I have found.

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MikeES
Update: After careful measurements the bore/piston sizing is a little tight. Bore for a .010 oversize should be 3.260 this bore measures 3.258. Std. piston = 3.243 this piston measures 3.254. Ring Gap OK except for oil rings. So it looks like I have the correct piston/bore relationship, just the wrong oil rings. Mike S.

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