1) I’m getting a back fire through the intake.
2) i have the FSM and have completely rebuilt every part, bolt, on this bike. total rebuild of the engine. new bearings, crank, pistons everything. in the head, new valves (wiseco) rocker arms, cam, chain…
3) i have the stator timing mark the "i" not the "h" set perfectly as the manual says, timing on top is perfect.
4) best i can tell TDC is on the compression stroke. intake valve opens gets almost all closed, then air compresses coming out the spark plug hole. i’ve tried to shift the timing 360 deg, but still having issues.
5) i don’t have the clamp for the throttle body (ordered) and you can see it jumps back. that’s from combustion not vibration. in all my auto rebuilds i’ve never seen anything like this. rebuilt one other atv engine.
6) last note, after i seated the valves by lapping them in i tested the seal with b-12. after a couple min i had some pass through. not a lot. surely, it’s a timing issues and not a valve issues right?
thanks for your time guys…
Please watch this video to describe my problem:
