Valve Adjustment

[DReese]

Can anyone tell me the correct way to adjust the valves on a 2000 400EX? And the specs?
Thanks Guys.

[TJ400EX]

They have a step by step how to under the EX Tech link above. Should do the trick.

[DReese]

Thanks!!

[beyer05]

Has anyone here ever put in a new cam and then not have the bike start? I thought it was the decompression lobe sticking because it ticked real bad when I started it. So after I got it unstuck, I readjusted the right exhaust valve and now it just turns over, but will not fire off. What is the deal?

[NJ300ex]

Your timing is off most likely. Did you adjust the valves while the piston was at TDC. I think thats the right info. I'm sorry if I am wrong about the valves, but your timing is deffiently off.

[RytM1]

Yup, I would go with the timing. When I put mine in, I thought it was correct, but it was 1 or 2 teeth off. It would start (but roughly), and had a loud ticking. It also wouldn't stay running after a while. Went back in, adjusted the timing again, and it runs great now.

[beyer05]

I have the T mark in the window with the cam gear marks lined up with the cylinder head, the other timing mark on the gear is straight up, and the lobes of the cam were installed facing down. I then turn over the engine until the intake valves are closing and then watch to align the marks. I then adjust the valves. The first time it fired right off, but was ticking real loud, so I assumed the decompression release was sticking when I made my adjustments, so I got it to release and then I readjusted them and now it does nothing but turn over. I have no idea what is going on! The only way I can get it to run is if I leave a bunch of slack on the right exhaust valve and I know this is incorrect.

[Leo]

sounds like the decompression release is holding the R exhaust valve open.. when that happens no compression = no start..

2 questions,

1- which way are you spinning the motor over as you line up the marks?

2- are you sure the pin/spring didn't fall/pop out of the head when you had the cam out?

Leo

[beyer05]

i am turning the motor counter-clockwise and I am not sure on the pin and spring. BUT, it will run with alot of clearance in the right exhaust valve.

[Leo]

your turning it the right direction.. (if you go clockwise, even a bit it will activate the decompression release and give you all sorts of trouble)..

it sure sounds to me like the decompression mechanism is activating and holding the R exhaust vavle open..

when you put a lot of slack in the R side exhaust vavle it allows the valve to stay closed even when the decompression release activates (which is what's letting the motor start)..

the decompression release is held in place by a spring, and small pin in a hole in the cylinder head.. I'd be giving serious thought to taking the valve cover off and making sure the pin/spring are still there.. and double checking my camshaft timing while I was in there :(

Leo

[beyer05]

Leo, can this spring and pin just fall out? I had the motor apart, but never physically removed it.

[beyer05]

Ok, the pin is in there but not sure about the spring. I pushed on the pin and it just went down in the hole but did not spring back up. Is this normal or is the spring gone? I had someone port the head and I never removed it. Do you think it could fall out and maybe he put in the pin without the spring?

[two_baaalls]

If it doesnt matter to you, remove the decompressor from the cam completely. Suggested to me by GT Thunder when I asked them if I should install one off my stock cam onto their cam. I've been running without one since winter, and havent noticed a difference.

[beyer05]

Yeah, Curtis Sparks says they do not recommend it, but who knows. LEO, I think my spring is gone and that is what is causing me problems. I am getting a spring tonight and will let you know. If so, you solved a problem for me no one else could, even sparks.

[Leo]

Originally posted by two_baaalls
If it doesnt matter to you, remove the decompressor from the cam completely. Suggested to me by GT Thunder when I asked them if I should install one off my stock cam onto their cam. I've been running without one since winter, and havent noticed a difference.

that is an option...

the primary reason that it was there was to help prevent kickback (which you definately don't want when kickstarting a bike)..

it doesn't lower compression while cranking, the only time it activates is if the motor starts to kick backwards..

I wouldn't bother putting it on an aftermarket cam, but I wouldn't bother taking it off the EX / XR cam either.. :D

Leo

[Leo]

Originally posted by beyer05
Yeah, Curtis Sparks says they do not recommend it, but who knows. LEO, I think my spring is gone and that is what is causing me problems. I am getting a spring tonight and will let you know. If so, you solved a problem for me no one else could, even sparks.

well, it'll either start -or- I caused you a heck of a lot of work for nothing.. :D

Leo

[beyer05]

The spring WAS missing, it fired right off. Thanks Leo!

[Leo]

cool..

now get that thing broken in and start ripping it up :D

Leo