ahhh, the knock.

c0le

New Member
May 20, 2008
39
1
0
I just recently rebuilt my top end, new piston and rings. I broke it in like i was supposed to, and around my third tank of gas it started knocking really bad. Its running basically the same, a little choppy, but the same. You can hear the piston moving up and down, its pretty loud. Could this be a broken skirt? or is it starved of oil? I have the block off kit, and i was running it 32-1 when it started knocking. Before i was running it richer because i just got it rebuilt. I want to say its the gas i put in it?
 
Wow dude that sucks bad!!! Dont know what to tell ya really unless it wasnt getting oil cause obviously that could breaj the skirt off ur piston....Why dont u take the head and maybe even the cylider off and check it out?? Im gonna start the break in on mine tommorow hopefully the guy at the shop tells me the correct way to do it!
 
yeah, i dont really have time today, but ill try and get the heads off tomorrow, as of now im dreading it considering sunday is my designated riding day :(
 
im going to start taking the blaster apart, probably just take the whole motor out and repaint the frame while im at it
 
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Yes... my spark plug is that yellow :(. Im taking a break now
 
after i take off the exhaust, where should i go from there? Just take off the head? I'm beginning to think this is a bit much for me, haha.
 
try tightening your skidplate. it may sound completly not related, but the sound clip isnt working, and on mine it made some sort of grinding noise i thought it was a bearing or someshit, i just tightened the skidplate, i bent the brackets/plates that hold it on and now its loose again, but much better. just dont bend the plates.
 
ok take the pipe off and shine a light up into the port, or the intake port if you dont got time to take a peak inside before you rip it totaly apart. it sounds like some mad piston slap. did you have the cylinder bored to the piston or just got a close sized piston? dont run it any more for sure though.

edit:

take off the head (5 bolts on top) slide that right off, carefull with the gasket. first of all, check out the top of the piston, then take off the 4 nuts that hold the jug/cylidner to the bottom end, then slide er off carefully and dont let the piston just fall when u take the cylinder off, get someone to help you with this part, just to hold stuff. not that complicated. oh and carefull with the base gasket, you may be able ot save it.

im thinking if its a broket skirt, the broken pieces would be stuck and jammed in the crank, i dont think she would run with a broken skirt.
 
first ill try the skid plate =D. Than ill take off my pipe, thanks to both of you, very helpful, and what causes a piston slap? it seems to be running ok and ive always let it warm up so i doubt its the skirt like you said. and i didnt rebuild it myself, i had a shop do it, and i assume they had the cylinder bored.
 
I would have check with them first dude! Shops can try and avoid doing extra work that "they" dont think u need....Go with what 89custom said take the head and cylinder off and check it out....take pics of the bottom of the head and in the cylinder and piston and stuff so we can try and help u out...good luck!
 
haha, a buddy or mine decided he was going to help and started unbolting stuff. in my oppinion its really a one person job, but when he left he forgot my wrench was in his back pocket? haha:-D