piston slap

IH10020

Member
Have a 12 hp Kohler in a play tractor with piston slap, anyone ever knurl a piston to help with this problem? Don't want to spend 1400.00 dollars to run 4 to 5 hrs a year.
 
My dad dabbled with that in the 70s, the knurl wears right off, you have to count on trapped oil to help after that.
 
Are you sure its piston slap and not a loose rod bearing? That is what I see most common in K-series Kohlers.
 
E-bay Kohler engine kits, and a seller will come up named bakt4kids, that has aftermarket kits for somewhere around $100, depending on how extensive the kit is. He's sold a bunch of them and got I one from him and put it in a 16 hp Kohler with good results.
Irv
 
You can get an aftermarket OH kit with a piston for under $100. NOT genuine Kohler, but not bad, either. HOW much can you muck around for that?

That being said, likely your cylinder bore is worn severely egg-shapeped (larger on the HOTTER exhaust valve side) and needs to be rebored to make it round again.
 
As noted by the other poster knurling is a pretty short term fix and good luck finding anyone who was the tool to do it. Are you sure it is piston slap? Skirt clearances can get pretty wide before audible noise begins, depends on which design piston is in it. Beside the rod camshaft end play is often overlooked by rebuilders but another common cause of knocking in high hour K series engines and sounds just like piston slap. . End play should be 005-010". As mentioned the aftermarket kits by Rotary Products are good stuff. I have used them in 2 dozen rebuilds with no problems.
 
Or you can have that 12 bored to 14 and use a std. piston,I've had good luck with these kits.If you stay with the 12,have it bored as necessary THEN order kit!!!!!
 
I've used the same guy on K301 and K321 engines with very good luck. The K321 is now 10 years old with a lot of hours put on it.
 

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