Yamaha G14 bent push rod

[joeltylr10]

So I just bought a Yamaha G14. It ran rough then stopped. Pop the valve cover bent push rod. Replace it and spin the motor by hand. SNAP the rocker bracket snaps. Replace it and spinning by hand the push rod wants to go to high. Cant spin the motor.

[cgtech]

strange, maybe newer JR6 style pushrod installed? have the part number for the pushrod you put in?

[joeltylr10]

J38-12154-00 Im baffled. Timing or crankshaft?

[joeltylr10]

Its Identical to the other pushrod.

[cgtech]

unless you, or someone else has been inside the motor, timing is Very unlikely the issue. if the balance shaft or cam gets "out of whack" it will hit the crank with CATASTROPHIC brilliance. check for broken valvespring. also you can push (hard) with your thumb and compress the valvespring & valve. press them both and compare (they use the same spring, so needed force should be same). also, look down the passage where the pushrods live and look for any junk, if there is any it would have nowhere to escape.

[joeltylr10]

Pushed on springs feels the same nothing down the tubes but a bit of oil.

[joeltylr10]

valve springs are good also. At this point do I pull the head?

[cgtech]

was it running good without excessive noise before? take the spark plug out, look in the hole with a flashlight. turn the crank until you can inspect the piston top, look for any strange "too clean" marks indicating if the valve has hit the piston. these motors will run forever, even when they smoke, this is odd. i own 2 G2s (same motor) they are pretty tough.

[joeltylr10]

It was backfiring.

[sho305]

I would pull the rockers and springs off, inspect all parts and how the valve moves. Something is not right there. If you set the valve lash I can't think of anything that would make the cam larger lift to do that, it must be an issue in the head.