Hey guys first post here .. anyways awhile back my blasters engine stared sounding like a piston ring busted and the piston was knocking .. well I bought a new piston and when I went to install it the other piston seemed to be perfect ,no rings broken no damage to anything .. well i installed the new piston to be safe and the things still making a loud knocking noise .. please help me!!
Rebuilt the top end but the engines still knocking
- Thread starter Blastaholic88
- Start date
i would say your sidewall clearance is out of spec giving you "piston slap". if this is whats wrong you need to bore it to the next biggest size and get a new piston.
get it bore to the next size and get a new piston, idk if it would be safe using the new one u put in
you know it could be the normal 2 stroke rattle.....or the cylinder might be outta round
this is normal
this is normal
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Yeah, check your cylinder as mentioned. If the rattle is worse than what seems 'normal', I'd check your rod bearings (big end, especially). A damaged rod bearing in the BOTTOM end of the engine can cause a rattle, even if the top end is fresh and within spec. Fixing this issue will require a new or rebuilt crankshaft.
Also, you might want to pull the clutch cover off and look inside. A loose main drive gear on the engine's crankshaft can really stir up a racket, especially at idle.
Ok well i tried to take the its just a normal 2 stroke noise advice cause their was no piston slap when we replaced the original .. It had great compression when we ran it .. but when i went out to start it the other day i was able to stand on the kick and it wouldnt budge... maybe a bearing??
Forgive me for bringing this post back from the graveyard, but the 98 has one more "problem" Im trying to solve... or at least I thought it was problem before I saw this post. The engine at idle has a knocking / rattle that I thought was out of the ordinary since my 94 you barely hear it, if at all. The 98 is much more pronounced. Had me worried but then I watched the video that was posted... and it sounds exactly like that Blaster. So this is normal?
Guess I was spoiled by the 94, because she doesn't have nearly as noticeable a "rattle." Oh well, one less thing to worry about I guess. Glas I did some research. Thanks again.
If it pings under load, it is your piston. If it rattles at idle, it is probably your main drive gear. My drive was loose and it sounded horrible before I fixed it.
new crankshaft, new bore, new piston new rings and it knocks when you let off the throttle while riding. tranny is in specs. drive gear is tight, new wrist pin and bearing... checked bore, it isn't out of round. it knocked at idle i took the baffle out of the silencer and the knock almost went completely away. thinking too much back pressure due to a stopped pipe or silencer. it seems to be blowing good out of the silencer. scratching my head.....even pulled cylinder and head and check crankshaft and piston again....everything is perfect but it knocks. my 94 didn't do this...this one is a 2002...
dont take my advivce but i woud do a leak down and compression test and go from there, and it might be a normal 2 stroke sound, you should take a vid and post it here.
will do a vid. no leak down, brand new bore and hone. new piston and rings, new crank bearings, new crank and rod. no leaks anywhere. plenty of power. just the knock. i removed the baffle from silencer and knock almost went away completely.
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