Kohler k181 rebuild smoking

[scotty 252]

Hi my b-80 i just rebuilt the engine on is smoking on throttle up. Is it normal? Is it the rings seating? If so how long should it do that. Thanks!

[squonk 39,016]

Could be the rings seating. But if the cylinder needed boring because it was out of spec in taper or out of round they may never seat. Also worn valve guides can cause this. When you say rebuilt , did a machine shop do it or did you just throw a set of rings in it? 

[scotty 252]

I put the new engine bearings, piston and connecting rod in. I did have the bore measured it was not out of round. But the bore was barely in spec at 2.941 and 2.940. If it is rings seating how long does that usually take?

Edited September 26, 2023 by scotty

[squonk 39,016]

Who measured the bore and with what

[scotty 252]

A had a friend do it he said he used a bore gauge. I got thinking i put engine assembly lube on the rings maybe that would do that?

[953 nut 51,955]

2 hours ago, scotty said:

is smoking on throttle up. Is it normal?

It will take a while to burn off the oil used during assembly. If the valve guides weren't replaced or knurled the throttle up smoking is likely to continue. It is best to break in the engine at wide open throttle under a load like mowing the lawn. 

[8ntruck 6,420]

What color is the smoke?  If it is a puff of black smoke as the throttle is opened, it is probably a carb adjustment issue.

[Gasaholic 183]

14 hours ago, scotty said:

I put the new engine bearings, piston and connecting rod in. I did have the bore measured it was not out of round. But the bore was barely in spec at 2.941 and 2.940. If it is rings seating how long does that usually take?

And was the bore honed to a cross-hatch, and then washed out with *HOT* Soapy water (scrubbed, really, with a clean cloth) and then oiled until clean oiled rag comes away still clean? (Hint: white cotton rag with clear 10W30 oil, should come out still fairly white with no black staining) Cross hatch in the bore is important for rings to seat, and the hot soapy wash is important to get honing grit out of the pores of the cast iron.  Rings won't seat well, and will take much longer to seat, if put in a smooth worn cast iron bore. If , after honing, you can get the spec to be .003" oversize they do (or used to) have a .003 oversize ring set to fit a standard piston for such cases.. and if bore still within out of round and taper spec, a bit more honing can sometimes get it to a .003 over spec.  Either case, there'll usually be a bit of a puff of smoke on throttle up until you get a little operating time on it (half hour to an hour at varying throttle speeds, which we used to get accomplished while tuning in the carb, governor & linkage adjustments after rebuild and then the test-mow.) 

Edited September 27, 2023 by Gasaholic