Can a Kohler K301 (M12) be bored .040" over?

[Pace F20s 0]

I have a Kohler k301 that is currently .020 overbored.  Can it be bored out to .040 over (safely)?

Thanks, Roland

[953 nut 51,882]

Have you found a .040 over piston? I don't recall ever seeing more than a .030 over.

[rmaynard 14,922]

I have never seen a piston and rings larger than .030 over. I think that if you don't have enough cylinder to work with to get a good .030 bore, you will have to have it sleeved. I which case, I would look for a good block that I can have bored to .010. It will end up costing you less.

Edited February 27, 2014 by rmaynard

[Pace F20s 0]

I found one on ebay at this link. Seller has over 60k feedback at 99% +.

http://www.ebay.com/itm/141204327453?_trksid=p2055120.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[rmaynard 14,922]

That is amazing. I have never seen that before. I think I will defer to one of our engine specialists to see if there is really enough material to bore that large.

[520HC 207]

I would think your cylinder will clean up at .030. Have you measured it?

[Pace F20s 0]

Have not accurately measured it yet.  That will be up to a machine shop.

Thanks for the replies.

[AMC RULES 36,954]

I would think that .10 or .20 would constitute a "safe" overbore.

[leeave96 487]

I would think that .10 or .20 would constitute a "safe" overbore.

Actually the kohlers are designed to be bored over at .010, .020 and .030 and they have piston/ring sets available. They also use to have rings (not sure about the piston) that is .003 over for when it was appropriate to hone the cylinder on the original bore.

When I read some of the incredible hours, 2000+ and more some folks are getting on their Kohler engines and then getting the same on a rebuild - that's a lot of seat time!

Edited February 27, 2014 by leeave96

[MalMac 1,328]

Like said, I believe there is a reason the Kohler engineers design the max bore being .030. anything else past that Is just too thin on the cylinder wall. If you could go over having such a thin wall I would imagine would get into cooling problems not to mention uneven wear.

[bmsgaffer 2,043]

If have a complete K301 for sale right now if you want to go that route. I am have not torn into it to see if it has been bored yet, but it runs great with no smoke so it should not need a rebuild for a while.

 

[oaktown1987 82]

I've heard u can safely bore a 12 out to a 14 bore

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[Don1977 604]

I've heard u can safely bore a 12 out to a 14 bore

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You would also need a 14 HP crank shaft as the 12 HP crank shaft isn't heavy enough as part of the weight has been milled off.

[oaktown1987 82]

I believe u still use the 12 hp rod

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[oaktown1987 82]

Even if it needs sleeved I wouldn't throw it out

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[Fordiesel69 221]

.040 is not a problem unless the cast iron is porus.  If you get it past .030 and see pitting in the cylinder, then you know you have one of these bad blocks.  But most K301's could be bored to a K321 and the crank changed.