- Jul 16, 2004
I picked up a 300exc recently that was completely torn down. I replaced, crank bearing/seals, etc within the motor. Got everything assembled and sure enough it fired right up with no issues until I turned around and half my street is a smoke stack. At first I had some issues with one of the o-rings on the head not seating so I pulled that and made sure it was seated properly. Next I figured maybe there is a chance the RH crank seal is shot maybe from being installed wrong but I did the crank breather test with the breather tube in water to see if any air bubbles or anything formed and nothing so I assume thats good. I am at a loss here and this thing is smoking like no other. Low to mid power is real jumpy but higher RPM's is hauls yet still smokes. Piston and rings are new so unless somehow the shop gave me the wrong size and blow by is the only other thing I can think of causing so much smoke. Only other issue I had when putting the bike back together was the exhaust pipe is a real PITA to get seated, could this be enough to cause this much smoke as its not combusting and burning. Below is a little clip of the smokestack.