Its a 05 crf450r and i just had the topend rebuild, All OEM parts. And i broke in the bike for 4 hours off and on and when i got on the gas in 1st i herd a CLACK then some ticking and then it locked up. And I had my brother take a look at the motor and he saw that one of the Intake and exhaust valves were kissing the piston on the right side and that very well could have caused the crank shaft to brake and f@ck everything up, because they didnt shim or mill it right. And when i took it to the honda shop they think it could be a malfunction piston and he will check with Honda and see what he can do. But heres some pictures and i couldnt get a picture of the dent in the piston but its there, So lit me know what you think and what i can do

 

Nothing.


I have had cases welded on a few bike but this damage looks bad. Have them back their work up, or get new cases and salvage the parts you can. The piston hitting the valves would not have caused this kind of damage.

 

A forged piston uppercutting a titanium valve cant cause the rod or piston to fail?

Is the Crank actually broken Travis?

 

Nop just the shaft just the shaft, And i dont think the bearing could have fail ether because then the crank would be twisted

 

Pictures aren't the greatest but it doesn't look like the valves took much damage. I think the problem was in the re-assembly of the motor, but not valve clearance. The piston was most likely up against the valves because the pin let go. Get some pictures of what is left of the piston pin, and did you find two cir-clips?

 

I'll like to see the motor with better pictures. Someone did not put this toghter right. How was it running during break in? How did you break it in?

 

Alright ill try to get better pics, And so far i have only found one pin and i dont want to take apart the motor quit yet unteel Honda shop gets back to me. And yeah it ran beautifully all around very crisp and clean, no clanking or bogging nothing like that it ran perfect and started right up

 

Dont take pics with the piston in your hand either set it on the ground.

I did get to see the piston, def a nice mark on the piston. maybe .010 deep.
had a valve been hitting a piston like that in a H series or equiv there would have been serious repercussions almost immediately.

Is it normal to Clay a motorcycle motor on assembly of the head? Isnt it also important to check P2V clearances? I know this is always done when we build our 4 cylinders but for motorcycles... i dunno?

 

Yeah the guy at the honda should thinks it was crank the got loos and cause that piston to go higher and touch the valves, BUT right were it hit was on the right side one intake and one exhaust valve, if that piston was goin up to high because of the crank wouldnt the denp be on JUST intake or JUST exhaust