Need some small engine help

[DaveN]

I just picked up a used generator, it has a Honda GX-340 11 hp engine. It smoked, but it ran good and the generator worked fine. I was fiddling with it trying to figure out why it smoked, and I'm a little confused.



Feel free to correct any of my logic down here - like I said I'm stumped.



I changed the oil, replacing whatever was in there with the correct 30W oil.



I did a compression test, I got 100~120 psi cold. I put a little bit of oil in the cylinder, the pressure stayed the same. So I think that means that the rings are good.



I took off the valve cover, and checked the vent that goes to the air cleaner. It seemed to be pretty clean, and I could get air flow through it to the air cleaner. So I'm thinking that the crankcase vent is working OK. One question though - is THAT the crankcase vent, or is that some other vent?



When it's running, it smokes a little on startup, then cleans up pretty good as it warms up. But you can still see it smoking - it doesn't fog out the yard but it's enough that I'm concerned about it. When you suddenly apply a load to it, you get a big puff of smoke then it settles down. I was doing this by turning the idle control on and off, I haven't tried running it with a heavy load all the time.



The load test tells me that the rings are bad, but the compression test tells me that they are good - I think. What am I missing here?

 

[scootergmc]

What color smoke? Bluish/Grey (oil) or black (fuel)? Try a leakdown?

 

[TowPro]

I would clean out the carb and adjust the high and slow speed jets. No telling how long its been sitting with gas in the carb. I run sta-bul year round to help prevent this kind of problem in every gas engine I own. (I don't own any gas engine cars).



I would say the rings are OK because the compression does not change with oil. The smoke might be just the high speed jet is too rich.

 

[DaveN]

it's a white/light grey smoke - and it smells like oil.



I wouldn't put a carburetor problem past it either - I don't get the impression that it was maintained very well, I think it was used and abused.



Thanks

 

[DaveN]

I have a dial gage style compression tester, I'm basically reading the peak pressures. I don't have a leakdown tester - thanks

 

[gonehuntingagain]

A larger quantity of smoke at startup than at running speed would indicate to me that the valve guides are not sealing like they are supposed to. I'm not that familiar with that engine, but I would look under the valve cover and see if there is a seal under the valve spring that you could replace.

 

[DaveN]

I checked out the assembly manual, there's not a "seal" per se but a guide bushing. It kind of makes sense that a little bit of oil is leaking past that. And it goes along with the rings not being the source of the problem, since I seem to still have good compression. I'll pull the valve spring and check it out.



Thanks-



Dave