K181 Specs

[Coadster32 793]

I am tearing into the K181 engine on the 854. I noticed that the Kohler manual says the cylider bore could be tapered .003 and be out of round by .003. Being a machinist, I think that's scrap, and can't see how the rings would seal. The motor is smoking, and plan on doing a valve job, and fully inspecting the cylinder as well. Has anyone used these tolerances as acceptable, and made good with a new set of rings?

[W9JAB 156]

As an "old motor builder" standard practice is for moving parts a .002 over size is

normal, the oil would fill that gap. Now this was for the Older Harley motors that

used a very heavy straight weight oil in an air cooled motor. With today's thinner

oils I don't think it would be an acceptable range.

[sorekiwi 761]

The way I look at it is that the engineers at Kohler know a lot more about it than I do, so if they say its OK who am I to argue?

And I also think that they would probably err on the conservative side when they publish specs - so I might take a chance if I'm close to the limit, but it'll be my own fault if it doesnt work.

As for oils, Kohler specs a straight 30 wt oil for summer use, why would you want to run "todays thinner oils"?

[VinsRJ 721]

I'm with sorekiwi on this one..... there's been times when I just honed the cylinder and ran it with new rings, no problems what so ever.

Straight 30 for K-serires IMO.

[Coadster32 793]

The way I look at it is that the engineers at Kohler know a lot more about it than I do

Point well taken. I won't know what I got untill I open her up. I suppose the easy route would be a quick hone, and a new set of rings. (I still won't make parts that bad though)

[buckrancher 2,678]

sounds right too me chris.

The cylinder should be bored straight

piston is tapered

.003 out of round and tapered is the edge of junk you must remember those tolerance's are the limit

if it's much more than .001/.0015 I would be boring oversize if you have

the motor apart

[sorekiwi 761]

Frickin Machinists!!

Yes the bore has to be a certain size, and the piston has to be a certain size, and the rest is the clearance. In 46 years I would expect there to be a little wear in the bore! I'd be pretty happy to have just .002" and I'd be happy to put a set of rings in it!

If I had someone bore a cylinder for me, I would expect it to be round and straight. But 46 years later I wouldnt be surprised if it was a little off...

[Coadster32 793]

Frickin Machinists!!

Yeah I know, it's a curse. I tell myself that all the time when I do house framing work. :)