XR 250 Auto decompressor problems

[mikecarvell]

Has anyone had issues with their auto decompressor. On my bike the one way clutch works, but it keepsholding the valve open andso the bike will not start.

The only way around it is to set the valve clearence very wide and then the bike starts perfectly.

Any help would be appreciated.

[416cc]

If the springs for the auto decompressor have broken they may well be holding the part that operates the exhaust valve open enough to cause you problems. Have a look see at the exploded diagram from the CMSL website to see which parts I mean. It may well require a stripdown of the top end to have a look see...not too difficult a job, but worthwhile.

honda camshaft partsmanual fiche xr250r 00 xr250 engine

[mikecarvell]

Thanks for the reply.

Took the clutch apart and all seems as it should and looks like the diagram, it is so frustrating!

Thanks

[416cc]

Is there a manual decompressor lever on the handlebar that might be holding the exhaust valve open slightly via the cable?
I have seen these levers bent in an off & cause all sorts of problems until the cable was removed.

[mikecarvell]

Hi,

It is definately the auto decompressor, manual is disconnected.

Mike

[Fat Bobber]

Mike,
When did the problem start, was it soon after you adjusted the tappets, perhaps?
When adjusting the tappets, you need make sure you rotate the engine a couple of times in the normal "forward" direction before bringing it up to top-dead. If you rotate the engine backwards it will engage the auto-decompressor and you'll get the gap set wrong. I think it's the right-hand exhaust valve that's affected, and getting it wrong would make the gap too wide rather than too tight, but still, maybe it's worth double-checking the clearances?
Good luck, let us know when you get it fixed.
Dave.

[mikecarvell]

Thanks for the reply.

Will be taking cam down at weekend to check it over again fully.

Mike

[mikecarvell]

Took it all apart, all ok!
Still holding valve open every other stroke....

[mikecarvell]

Problem sorted, as advised by many others.........I removed it and it all starts and runs perfectly!