yz250 knocking

Joined
Jul 28, 2007
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#1
my 99 yz250 has this nice knocking sound in the head on idle and when reved slowy gets faster ,and when u move the kickstarter slowy u can feel and hear the knock when the piston change direction,it has had a new piston and rings put in not too long ago ,u think it mite b the connecting rod bearings??and if so is it hard to change your slelf??
 
Joined
Jun 20, 2007
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#2
it could be the piston banging on the head, try to fit a thicker gasket in the base of the cylinder just to have sure, or else try to get a solder wire trough the spark plug hole and bend it to touch the cylinder wall, then move your kickstarter to crush the solder...
if the piston cuts the wire you have your piston hitting your head.
if not, just mark the wire or dont touch at all, probably is your big end and the rod. maybe with too much piston to cylinder clearence too...

if no one touch your top end since the rebuild and it was good some time ago forget the idea of piston hiting the head

i would recomend you to ask a nice shop to rebuild you big end with a new connecting rod, because besides the dificulty to get it right you must have some special and expensive machines...
sometimes its cheaper to buy the cranckshaft ready to assemble then is to get your rebuild... do a good search..

its not very difficult to get your crank off, if you know what your are doing, otherwise ask someone to do it since you could easy wreck or damage something

oh, change yor bearings to..


good luck
 
Joined
Jul 28, 2007
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#3
thanks man,the piston is not hitting the head as i have the exust off and have checked the piston all looks good in there,iam just going to get it rebuilt at a shop .thanks