85 Moto 4 questions

[fivepointfivesi]

First off i would like to intoduce myself, Im from the frozen state of North Dakota. I have worked on cars all my life, not atv's.
Now the time has some to learn something. I just purchased an 85 yamaha moto 4 200N, The other day i was driving it for the first time and it seemed to run good.
So i got it in the shop and put a battery in it and did some wiring. I started it and noticed that it was blowing alot of smoke out the exhaust. :cry:
Smelled alittle like oil but not completely sure. The gas smells alittle old, will these smoke alot if they have bad gas? And if the rings are bad, can i do the top end without pulling the engine?

And i noticed the rear end was over full on oil and it smelled like engine oil, is it possible for the engine to leak oil down the shaft tube into the rear end?

Sorry for the long post but, its easier to ask em all on one post.

[steven 250sx]

welcome to the forum and the smoke cud be old gas is it blue smoke?and yes it could be engine oil but like you said you just bought the bike maybe fore soem reason some one put oil all over the rear end (ppl are weird) just keep checking your oil and i'm not 100% on removing the enigine for top end but i think you do

[fivepointfivesi]

After putting fresh gas in it, it still smoked. So i just ordered a new 10.25:1 Wiseco piston. and took the cylinder to be bored .5mm over. Now after its all back together, will i notice any significant power gain?

[scooterroo]

you might notice a little bit, but not alot. inorder to get more power you need to open it up and let it breathe, just like a car. bigger carb, better airfilter, aftermarket exhaust...etc. thats all motors are is basically an airpump on steriods. the more air going in and coming out, the more power!!!