Knocking!

[screaminta]

I have this knocking sound coming form my motor. It is the exact same sound that someone had already posted about with that video..but I cant seem to find that thread now. I know its not piston slap because I just put a fresh topend in and I know that the piston is not hitting anything thats its not supposed to. I was thinking that it may be the balancer bearings or something...any thoughts? Oh yeah, the noise gets quieter when you pull the clutch lever in..not much quieter but a little...so tell me what you guys think...thanks

[beerock]

its always good to change the counter balancer bearing on the gear side every year or every 70-100 hours. the knocking could be the peculiar knock the 250r has always had.
you may want to check the clutch backet needle bearings for play. they sit inside the innerhub on the countershaft. there is a fair amount of play on the clutch basket. so you could just be hearing the infamous 250r knock. even new R motors do it.

[screaminta]

hey beerock..i dont know if it is the infamous 250r knock because this is my first 250r....and by the way where are you in jersey cause i live here too...anyway if any of you remember that video that some memeber here posted a while ago about his knocking sound, mine is the same just not as loud..

[beerock]

Originally posted by screaminta
hey beerock..i dont know if it is the infamous 250r knock because this is my first 250r....and by the way where are you in jersey cause i live here too...anyway if any of you remember that video that some memeber here posted a while ago about his knocking sound, mine is the same just not as loud..

the one with the R idling? they all sound like that.

where in nj are you?

[screaminta]

hey beerock...check ur private messages..

[hollywood250r]

Even with a new top end it could be piston slap. Especially if it is a short rod motor!

[screaminta]

i dont see how it could be piston slap? can you explain?

[hollywood250r]

Short rods are known for piston slap due to the increased rod angle! You can have a fresh bore and a new piston with the correct cylinder to piston clearance, you will still have piston slap. That is the skirt of the piston hitting against the bottom of the cylinder.

[screaminta]

so what can i do about this short rod piston slap?

[beerock]

nothing:p

just check the piston to bore clearance if your worried with feeler gauges i think it .003 is in spec.

not sure though, look in a manual

and you need to measure it at the bottom of the piston where the piston is at its largest size

[2nd sucks]

when i got my brand spankin new pv 265r motor back from the local race shop it was knocking like hell. so i called up and spoke to the guy that did my motor work, and after about an hour of arguing on the phone, and him explaining it to me i finally knew what he was saying with the short rod slap

so i would say....if you piston/bore clearance is within spec dont worry about it too much...get a louder pipe:macho