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Discussion Starter · #1 ·
Hi all, i ahvea bolens ride a matic with a small bore kohler k161 engine. The engine has a 20 thou over piston in which is to say the least knackered. As they are no longer availible has anyone ever successfully bored one to take a STD big bore piston and rings?

Any help would be appreciated,
James
 

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Do a search on this subject and see what comes up. If you talk to a shop that does a lot of Kohler work they may know. Since you are already +.020 you would need to go another .02 roughly to fit the larger piston in there.
 

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Discussion Starter · #4 ·
thanks for the reponses, this is why i am asking. I have read on another site via a google search that the casting for thre block is the same on big and small bore engine meaning wall thickness wouldnt be an issue. Does anyone know anything about this?

Many Thanks,
James
 

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One of those strange situations where an engine had 2 different piston sizes. If the blocks are the same it should be doable. There may be someone here who has done this already.
 

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Funny you asked. As we speak my K160 that has the original 2 7/8" bore is at the shop being bored out to the larger 2 15/16" bore. The piston is the exact same dimensions EXCEPT for the diameter which is 1/16" bigger. There is plenty of room for this to be done. If you want, wait a couple weeks until mine is all back together and I will tell you how it goes. The rod is exactly the same as well. I did months of research before doing this to my motor.

Edit- You are only talking about a .0625 over bore instead of .020 that you already have (roughly .040 difference...it's not really a major difference with all the room that is available.
 

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I asked a guy I work with that machines and builds engine on the side. He does everything from these Kohlers to full blown race motors for stock and drag cars. He said you can go .060 over or better on the Kohlers. I fully trust his word.
 

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Discussion Starter · #12 ·
Well thannks for the replies. Ive ordered the bits and in going to give it a go. i have nothing to loose as the current piston is as slack as a cock in a sock anyway.

Thanks again,James
 

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Discussion Starter · #14 ·
Thanks for the replies, i am going to collect my engine tomorrow morning from being bored so i will get some pics and keep you al updated. antiquetractors, i hope your engine is all going well!

Thanks again,
James
 
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