K321 to K341 upgrade

[UK321 3]

Hi everyone,

Great to find a forum dedicated to my favourite tractor.

 

I have three at the moment and one I've just acquired is a C125 fitted with a K321 engine. I bought it as a known non runner and found that the conrod had disintegrated.  I wanted to get it re-bored so, fancying a little more power than my last C125 I had it bored out to 3.5 inches and duly bought a rebuild kit from the US for a standard K341.  My questions are:

 

If I use the crankshaft from the K321 do I need to get it re-balanced?  It's in good shape though I would get it ground.

If I don't get it balanced and, bearing in mind it is for mowing so is hardly ever idling, will it shake it to nits? and, finally

Does anyone know of the whereabouts of a half decent crank from a K341 that might be bought?

 

Thank to all.

Martin

[ebinmaine 67,474]

Hello Martin. I don't specifically have the answers for you but you could do a web search for Brian Miller. Huge huge volumes of information about Kohler engines.

[rmaynard 15,456]

On 3/17/2018 at 10:01 AM, UK321 said:

I had it bored out to 3.5 inches and duly bought a rebuild kit from the US for a standard K341.  My questions are:

 

If I use the crankshaft from the K321 do I need to get it re-balanced?  It's in good shape though I would get it ground.

If I don't get it balanced and, bearing in mind it is for mowing so is hardly ever idling, will it shake it to nits? and, finally

Does anyone know of the whereabouts of a half decent crank from a K341 that might be bought?

 

Thank to all.

Martin

 

The K321 is already bored to 3.5 inches. That's the standard bore for that engine. A K341 is 3.75 inches. Kits for a K341 will not work in  K321.

[UK321 3]

rmaynard

You are, of course absolutely correct .  My digital dyslexia got the better of me.

 

It is a K301 which I am upgrading to a K321 so is now bored out to 3.5 inches.

 

ebinmains, thank you... I shall look up Brian Miller and, no doubt, benefit from his knowledge.

 

Thank you both for your help.

Martin

[rmaynard 15,456]

Someone please correct me if I am wrong here, but the maximum allowable bore on a K301 is .040 over. With the standard bore being 3.375, .040 would make the maximum bore 3.415. If you have bored it to 3.50, you are getting mighty thin and are inviting some major damage. 

Edited March 22, 2018 by rmaynard

[richmondred01 2,237]

I agree with Maynard. You can go .040. 

I never do because the k301 blocks are still plentiful.  The max I go to is .030. 

If you have it at 3.50 your over and the engine will fail.  

If you have some sort of emotional bound with that block I would sleeve it before going to .040 but that’s just my American two cents. 

 

Edited March 26, 2018 by richmondred01