I have a 150cc gy6 engine atv. I put a new carb and battery in it and now it smokes blue smoke like crazy. When I think of blue smoke makes me think burnt oil. But I guess I'm not sure if the carb air and fuel mix screw might have anything to do with this? The carb is new and definitely needs it's tunning. So can anyone help me out? Is it time to tear into the top end and buy a rebuild kit or how should I go about figuring out why in the world is smokes like a rich running 2 stroke? Thanks guys and girls.

 

Forgot to mention, exhaust fumes of engines burning oil and those with excess fuel smell totally different, those burning oil give a two stroke smell, excess fuel smells like a WW2 army jeep on choke.

 

If its blue its oil, black is to much fuel white is water, pull the plug look at it see if it is oil soaked do a compression test and a leak down, it could just be valve seals does it go away after a few minutes or get worse?
And BTW make sure you didn't put mixxed fuel in it

 

Okay so here's my reply to both your questions. I took the air box off it was as clean as a whistle no oil there. The original carb was awful looked like syrup in it so of course I bought a brand new one. That's when it started with regular gas not mixed. As soon as I started it she smokes a faint blue smoke during idle when I rode it for about 10 minutes the more throttle I gave it thw thicker thw blue smoke. It also seemed like it has little to no power at the time. I have no other oil leaks or anything coming from the case of any kind. But when I set the air screw mix screw I have it at 2 turns out, not sure if that could be the cause. I'm thinking it's somehting In the top end.

 

Anyone know what a good compression would be for a 150cc gy6 4 stroke engine? I'll do a test today

 

Okay my psi compression test came out as 100 psi. But other times came up at 80psi. So I looking in the top end valves look great. My cylinder is stuck anyone know how to get it free so I can look at the piston?

 

Timing chain and gears make sure you know where and how it goes back together before you do this.

 

Yes. I already have dealt with the timing on it and know how to get it back in time with the cam shaft. The cylinder is stuck on there. Tapped it lightly with wood and a hammer but it won't break free from the seal. So I cannot check how my piston looks.

 

Ah ok gotcha I would think high tach or something was used but you can check if there is a lower bolt pattern my guess is it is just stuck?

 

Yea I've looked everywhere for any hidden bolts, but nope. I mean this thing is stuck!! I'm afraid to keep taping on it in fear of possibly breaking the head itself. But for now while I'm racking my brain I'm taking apart the valave springs to see if hopefully is the seals. Lol please let it be the seals so I can have this problem solved.