I had my engine (topend) rebuilt about 9 months ago. New piston, valves ect. all the good stuff. I broke it in nice and easy and it runs great. I have a 125 main, the needle dropped down 1 notch and a 40 pilot. After about the 3rd month after the rebuild (I would say about 10 hrs on the motor) it is blowing out blue smoke ONLY when I start it up when the motor is cold. It only blows blue smoke for about 10 to 15 seconds and then stops and does not ever do it again until I leave the motor off like overnight. Any ideas? Valve seals? Will this cause any damage? I think I have a one year warranty on the rebuild.

Thanks.

 

Blue smoke on cold start-up means worn out valve guides. It probably wouldn't hurt for new rings either. I don't know why so soon after a rebuild though.

 

it might be the gas you use because my brothers we run on 4-star not unleaded and because 4 star is alot stronger it makes more smoke but makes the quad abit quicker

 

what pushinthelimit said is conventional wisdom about valve guides but I have found them to basically never wear out on Honda's engines. Valve seals are a possibility too, but almost every time I've seen this on a Honda it's rings that fix it.