New to me G29 with a bad smoking habit

[rojo143]

Hello everyone this is going to be a little long winded but I am new to the cart world but not new to engines or mechanics. I have a new to me 2011 G29 carb cart. The cart live a rough life before me and I got it cheap because it smoked pretty bad while running. Since I got it home I pulled it apart and cleaned everything so I could begin trying to source the reason for the excessive smoking. I initially started with and oil change and tune up kit to start fresh (which it had a lawn mower size spark plug in it). After changing the oil and running it for about 45 minutes total I checked the fresh oil and it was already black and smelled like gas. So I changed the oil again adjusted the valves to within specs, cleaned the carb and replaced the fuel pump. The cart is still smoking although better than initially, but still excessive. I guess I am looking into opening up the engine to look at the rings. My main question is how likely am I to have to bore the motor? Or are these pretty resilient engines.

[Mjmck]

Check out my build thread for some images. Start off with a compression test to give you an overall idea of engine health. As long as the bore isn't pitted or nicked for any reason a hone can suffice if within tolerances. My cart had 125 PSI compression and was a mosquito fogger.

[rojo143]

Originally Posted by Mjmck

Check out my build thread for some images. Start off with a compression test to give you an overall idea of engine health. As long as the bore isn't pitted or nicked for any reason a hone can suffice if within tolerances. My cart had 125 PSI compression and was a mosquito fogger.

I forgot to mention that I did a compression test and it was 122 psi which according the service manual I have is withing spec. I will check out your thread. Thanks

[meimk]

You could do a compression test first. Might tell you something without a full tear down. Also, I have found several of those Yami engines to have a bad valve stem seal on the intake valve. A relatively simple and cheap things to try before you tear down the engine.

[rojo143]

Here are some pictures of picking it up tear down and cleaning, the oil that was in it and the way it sits at the moment until I tear it back apart.

[Mjmck]

Might want to double check those compression numbers being in spec. My G16 is supposed to be around 170 IIRC, they will run that low as we know but they should be better than that.

[rstacy]

Is the oil level rising?
What you are describing sounds like a cart that has been running on gas with ethanol.
The ethanol ruins the rubber tip needle. Now the needle doesn't seal properly and allows excessive gas in to the cylinder which will mostly burn while the engine is running. After listening to enough engines with this problem you can actually hear the problem when the engine is starting. Its a slight burble sound as the engine starts.
The bigger problem is that while the engine isn't running gas continues to siphon in to the cylinder, past the rings and down in to the oil. Now the thinner oil gets past the rings and causes the engine to smoke and contaminate the muffler so that even after you replace the needle and change the oil, the car will still smoke for about an hour while it burns the crap out of the muffler.

Of course it could be that your rings are shot and its time to hone the cylinder and install a new set of rings. This is probably the case if your oil level is not rising over time.

[rojo143]

Originally Posted by Mjmck

Might want to double check those compression numbers being in spec. My G16 is supposed to be around 170 IIRC, they will run that low as we know but they should be better than that.

According to the YDRA service manual I have these are the listed compression specs circled in red. Are these accurate or should I be looking for a higher compression number?

[rstacy]

G16
Standard - 164 psi
Minimum - 142 psi

G29
Min - 97.7 psi
Normal - 111.6 psi
Max - 125.6 psi

[Mjmck]

Originally Posted by rojo143

According to the YDRA service manual I have these are the listed compression specs circled in red. Are these accurate or should I be looking for a higher compression number?

Thats is crazy and surprising so much difference, anywho I stand corrected.