Bruin 350 engine knock at idle

[rough rider]

I have a 2006 bruin 350 when it idles it has a knock which sounds like it is coming from clutch area, I had clutch off and greased rollers etc. cant quite find what is making the noise, runs good doesnt burn oil .???

 

[moto4_lane]

do you need your timing chain adjusted?

 

[NOSMOKE]

The timing chain has an automatic adjuster. Is the noise always there - does it go away when it warms up? I have an 05 and there is a slight noise on start up . It goes away after a few seconds. I have the engine apart and saw no cause for the noise

 

[maim]

nosmoke has a collapsed piston skirt. if it goes away when warmed up that is the problem.

 

[NOSMOKE]

I do not have a collapsed piston skirt - I know this because I have just installed a new yamaha piston in addition to a new timing chain and gear set along with new chain guides.

 

[maim]

new piston did not rock in the cylinder when you installed it? (without rings)

 

[NOSMOKE]

the piston has the correct amount of clearance as per the yamaha specs measured by both the machine shop and myself. The noise does sound like it's coming from the clutch side and it goes away quickly after start up.

 

[maim]

this is a good one. oil screen is clean for the pump? i know sounds dumb but has happened to me on a dirt bike.