Motorcycle Repair: Exhaust leak, piston cylinder, yz490

Question
Mark,
    Hi, I just got my hands on a 1983 YZ490. The bike is in great shape. The problem Im having is where the pipe meets the cylinder head theres an exhaust leak around the pipe. Its not so much the smoke, its the Engine oil thats pissing out and a lot of it. Is this normal or does this indicate a new set of rings is needed. Also, In the manual it says to mix Yamalube "R" at 24:1. Isnt that too much oil.
                                   Thanks,
                                    John

Answer
Hi John,

That's fuel/oil "premix" thats oozing out of the exhaust port, not engine oil. The amount sounds excessive. Do a compression check to see how the rings/piston/cylinder are sealing. If compression is low, measure cylinder wear (or have a shop inspect it for you).

Yamalube R premix at 24:1 is rather lean, but OK. Most premix recipes are 32:1 or 40:1. Go with the the manual's recommendations.

Respectfully,
Mark Shively