Knock sound-YZ465

[2stroke]

Raced my 465 this weekend. Halfway through the last moto I noticed a knock...sort of a diesel sound...The frequency made me think it could be the piston, but it sure wasn't running badly. Happened most noticeably at lower RPMS/load. Getting on it hard shut it up, and I also head it in neutral later back at camp.

This much I know, the clutch basket was loose when I bought it at the beginning of this year, previous owner suggested buying a new one, but I took a look and decided to run it a while......

I was being a little harder then usual on the clutch at this track, third gear all the way and feathering it in the corners, etc.


Can a clutch basket give you this sort of noise? In some other motos before this, I would hear a chatter if I let the RPMs drop too low in too high a gear, probably related right?
Im going to pull the clutch cover soon, but I wont be able to get to it for a while.
Thanks for any ideas!

Edit: The top end and crank and crank bearings all have at most 4 hours of novice time on them.

 

[High Lord Gomer]

What do you mean by the clutch basket being "loose"? The nut that holds it is loose or it is notched?

I would lean more toward a spark knock than a clutch making noise.

 

[2stroke]

Loose, as in you could hold the basket finger area with one hand and the back of the basket with the other and there was some rotational play...not like clackity clack mind you but noticeable. ....some notching on the fingers as well.

Im done for the season and I have to get a new basket either way....as for spark knock...what do you mean, the piston hitting the plug? I did pull the plug between motos....wonder if the gasket fell off....

Thanks for the reply!

 

[dirt bike dave]

He means spark knock as in detonation or pre-ignition.

Most likely to occur under heavy load and low rpm, and something the old aircooled open class bikes are known for.

 

[2stroke]

Yep....that makes perfect sense. I was running a much lower octane than usual! (running late that morning, filled my track can with the same garbage I feed my old van!) LOL!

In the morning some of the gas in there was from last race, and as i put more in thru the day it got progressively crappier!

Still got to get a basket though but that was a scary noise!
Never had that in my KX400 or F9, but they dont have nearly the compression that the 465 has.

Thanks again guys!

 

[chrisnoel]

worn clutch springs

chattering at low RPM would have me buying new clutch springs but other mystery noises at low RPM's would have me worried about pinging. Cheap gas, too hot of plug, high compresion, running at altitude?