timing chain replacement

[JACK STRAW]

at what interval should the timing chain be replaced.we do trail and pit riding and sometimes pretty hard but not wide open for long periods at all. they are serviced regularly with gn4. thanks

[CJM]

Generally there is no real interval.

Next time you have the rocker cover off grab the chain. It should have NO slack. Id say when you do a rebuild its time to do the timing chain.

If you do replace it, one from an 02 crf450r is not only cheaper but more hd and it fits. you should also replace the tensioner and the the guides if the guides are worn.

[JACK STRAW]

if the tensioner and guides are worn do they get replaced with my model or a different model?thanks
this had me thinking when a kid down the road lost his motor on his 300ex from a broken timing chain last week

[dxcody]

Unfortunately there isn't a cheaper route to go on guides.

They are expensive.

I think the last time I looked they were $80 for them both or something like that.

There is other options on the tensioner but stock is the way to go in my opinion.

Though, I doubt you will have to replace it.

I have never had one go bad on me.

Just take that little phillips head screw out of the back of it, and there is a small flat tip slot down in that hole.. You just turn that slot with a small flat tip screw driver clockwise? I think it is clockwise, until the tensioner shaft is all the way sucked in the tensioner , and pull the screw driver out.

If the shaft springs back out, you are good.

If it doesn't.. Replace it.

[DragonGunner]

My 400EX made in Aug. 1998 still has the original timing chain and guides and tensioner...been rebuilt 4 times and tons of Hard riding hours and racing.....I'm stiil waiting and wondering when the timing chain is going to break....LOL.