Knock in top end

[ThunderChicken]

I recently noticed a knock in the top end of my '87 250r. I was getting ready to sell it and was running it without wearing a helmet which I never do and this is when I noticed the knock. I removed the spark plug and yanked the cylinder with the cylinder head still attached. I found that there was no excessive play with the rod or in the wrist pin. So I put it back together, put new gas in it and started it. The knock is still there. The cylinder walls looked fine and the piston and rings only have a few hours on it. I only notice it at idle, because when I am on the throttle, it screams. Overall it runs great. I don't want to sell it if there is something wrong and the unsuspecting buyer gets it and it blows up. Is the knock normal or should I be looking elsewhere?

[f4istunna]

Mine has had a little knock since i got it. I rode it all year like that pretty hard at times. Ive heard a few others that sounded the same.

Might just be your used to the helmet. I always get paranoid when i take a spin w/ out a lid because i hear all the motor noises lol.

If everything seems to be in spec and its not to obnoxious of a tap id say you should be ok. Dont quote me on that though :D

[xlr810]

when you installed new rings did you go with new wrist pin circlips and wrist pin bearing?

If you answer yes to all of the above and your ring end gap is in spec, then you're probably fine. All R motors make some knocking sounds.

[methyman]

It could be the counter balancer for the crankshaft. Pull the clucth cover off and see it the counter balancer bearing is bad. If it has play up-down or left to right it is bad, it needs to rebuilt.

[Mikeman1]

Originally posted by methyman
It could be the counter balancer for the crankshaft. Pull the clucth cover off and see it the counter balancer bearing is bad. If it has play up-down or left to right it is bad, it needs to rebuilt.

Or the clutch can make some noise when engaged in neutral.

[trx310R#24]

i know what sound your talking about mine has been making it for years lol its not anything bad its just how they sound

[ThunderChicken]

Thanks to all who replied. I have been riding lately and it is running like a bear. I am not going to worry about it.