HELP! top end rebuild question!

ok here is the story. i got  a new piston kit to rebuild my top end and everything was going smoothly until the piston fell out of my hand when i was going to put it on the rod and left a very very small ding on the brim of the piston. nothing big. in thinking that it never touches anything it would be fine and i went ahead with the rebuild. i figured the rings rode the cylinder and that the piston never comes in contact with the top and it would be fine. well after getting it all back together it fired right up just fine and runs good except I'm hearing a clanking or small knocking noise now that is not normal or i never heard before. my 2 questions are could the dent be the cause of the noise ? and if not then what could be making this tapping noise. i went back and double checked the timing, the tensioner, the chain guides and everything and all was fine. pease help me out if you have an idea. thanks!  

 

its a 2009 yz450f 

Edited by motoxking989

Pistons are designed to take all kinds of abuse, drop checking on the garage floor is not one of them.

I agree with dlk. I would've bought a new one. Did you check for any connecting rod play?

I agree with dlk. I would've bought a new one. Did you check for any connecting rod play?

yes no play at all. 

Pull that thing out, before you ruin something...like the topend.

If the bike has an aftermarket skid plate, remove it, then re-evaluate the sound.

 

If it's still abnormal, pull the cylinder and have a look at the piston to see if it has any odd contact patterns on it.  What kind of piston was it?

If the bike has an aftermarket skid plate, remove it, then re-evaluate the sound.

 

If it's still abnormal, pull the cylinder and have a look at the piston to see if it has any odd contact patterns on it.  What kind of piston was it?

thanks man! and thanks y'all but we figured it out. i had the cylinder honed to knock the glaze off and the dummy at the machine shop took too much off and the piston had to much play and was slapping around. 

that sucks now it needs a jug or larger piston :(

Edited by sleepy514

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