2003 YZ85 Chain Guide Block Question

[deadhead]

Folks,

We are experimenting with a 49 tooth rear sprocket on my son's 2003 YZ85. It works well, but it's eating through the chain guide block on the swingarm--cutting through it like, well, a chainsaw. Is there anything I can do/try?

Thanks,

deadhead

 

[Jasle]

sounds like yer chain is too tight. Are you setting your tension of the chain when the swingarm is parallel to the ground? Or else 3 fingers of slack when the bike is off the ground. Measured at the back of the top swingarm guard.

A larger front sprocket helps get the chain off the slider but that is like changing the rear sprocket smaller by 2.3 teeth.

 

[deadhead]

Jasle,

I'm talking about the chain guide block at the back of the swingarm underneath, not the chain slider. I know the chain is not too loose, so it must be the added diameter of the 49 tooth sprocket.

deadhead

 

[deadhead]

Is there a different chain guide block assembly for a big-wheel YZ85?

 

[xcracer725]

not sure i have a bigwheel yz85 but i did not stick the kit on it.....i know it has a 2 inch longer swingarm

 

[Jasle]

maybe you need to add some length to the chain. Possibly its too close to the block now. I could be totally off though. I thought they came stock with 50? When going up sizes the wheel comes forward more. I have seen interference problems when fitting larger sprockets.

 

[deadhead]

Jasle,

I left an extra link in when I fitted everything up initially and it was almost at the far end of the adjustment. Wouldn't have lasted long. The stocker is a 47 tooth. We were running a 48, and decided to try the 49. The big wheels come with 52s stock, which is why I asked if the parts were different. However, I got a parts list from Australia and that indicates the chain guide blocks are the same. I may need to run the chain a little on the tight side.

deadhead