Honda 200x, White smoke, oily plug. Help please

[Jeremy_red]

Hey guys, I have a 85 200x that is giving me a hell of a time. I had alot of white smoke after revving the throttle and warming up a bit.
Lots of white smoke, with Black oily plug.
So I replaced the rings and valve guides, set the timing, set the valve clearance, cleaned the carb, made sure the top end dowel pins were in. Still same thing, smokes like a .
The cylinder looks ok, and piston too.

Any Ideas? What else could it be? Ive taken this motor out like 5 times and same thing every time. White smoke

[fordtech90]

Well it sounds like the 5 times you had it out you didnt take time to have cylinder measured for out of roundess or just taper. Rings wont make a difference if they cant seal properly and better yet even if it was within spec and you didnt properly hone the cylinder the rings wont seat and itll keep having oil get passed rings, or if rings were improperly installed one could be stuck or broken and doing same thing. Also valve guides wouldnt do any good if the valve seats were worn or valves were bent or too worn...not trying to be pessimistic but should be obvious once measured or properly inspected. Another thing to consider is that the smoke your seeing is from old oil built up in exhaust before rebuild.

[Jeremy_red]

I did hone it, But I didnt measure the cylinder wall for roundness. I will pull it out again and see. If it is egg shaped, I guess the next step will be buying a new cylinder.

[fordtech90]

Doesnt mean you have to buy a new cylinder it can likely be bored and select fit to the oversize piston you purchase. Make sure you choose wisely on machine shops though a few years back I had a honda dealership send off my jug to be bored and select fit they bored it .40 over when it only needed to be bored .20 over and it was more out of round when I got it back then it was when it left.

[Jeremy_red]

I measured my cylinder and piston. The piston is .50 mm smaller than the cylinder.

piston 64.30
cylinder 64.80

Am I correct to assume this is the culprit?