400ex wont kick over sometimes

[vroom4]

Recently i acquired a quad from a friend who said it was fubar'd. He told me that it ran and tapped really bad and then one time he tried to start it, it wouldnt kick over.

I can get it to kick over sometimes and othjer times it just doesnt budge. If i just keep trying every 3rd or 4th try it kicks over. I checked the valves and they are gapped correctly.

What do you think i should check?

I think it might have something to do with the cable that opens/closes the front valve pair when u kick the motor over considering this one barely works and the spring is just flopping there.

AIM: Jeepin97tj

Thanx guys

[plkmonster2]

Sounds like the timing jumped, and the valves are screwed up. They are probably hitting the piston. You should be able to kick it over without the decompression. The only bike that I haven't been able too without the decompression are the new 450's.

[GPracer2500]

Is this an XR400 engine in a 400EX?

[vroom4]

Originally posted by plkmonster2
Sounds like the timing jumped, and the valves are screwed up. They are probably hitting the piston. You should be able to kick it over without the decompression. The only bike that I haven't been able too without the decompression are the new 450's.

Is there anything i can look for that would indicate the timing skipped? when i pulled the top end off the bolt that hold the cam and gear together was stripped so i replaced it. I figured no harm done considering everything looked in tact and good.

[vroom4]

Originally posted by GPracer2500
Is this an XR400 engine in a 400EX?

im guessing its just the stock motor considering my friends knows nothing of mechanics.

what should the cable valve thinger be doing when im kicking it over.

[plkmonster2]

If the bolt was ever out and the engine was spun, the valves may have been stuck open, and the piston could have struck them. I'd line up the timing marks on the top end, and see if they line up on bottom. Not sure exactly where they are though.

[vroom4]

i tried finding any marks on the belt and there are none. Just lots of things that say japan and what not. I did see one tiny arrow if that is anything.

[vroom4]

well i think the timing skipped 1 tooth because the dash's onthe cam gear are slightly off level. Would this cause my valves to be out of whack?

When i lay the valve cover on with no bolts and kick it over its flat at one point and then the valves come up so far i cant even bolt the valve cover on.

Diagnostics? Fix?

[plkmonster2]

Does it kick over fine with the cover off? The valve must eb hitting it. The marks are on the cam gear. they lay parallel with the head I think. The other mark is on the flywheel. There might be a timing hole on the case.

[GPracer2500]

It must be an XR400 engine because the EX engine doesn't have a kickstarter or a manual decompression lever/cable. The XR does.

[vroom4]

does the 300ex have these? It must be a 300ex. Its hard to tell with no plastics and never having seen a 300ex before. Anyway it looks like my timing is off 1 tooth so whats the next step guys? Pull the head and check for damage to piston and internals?

[vroom4]

and yes it turns beautifully with the cover off. On one stroke exhaust is open intake is closed and vice versa. i dont see how that little bit of difference could cause it to hit the cover.

[400eXr1d3rZ]

Does it have kickstart? Or electric? I dont quite understand what you mean


I might get a xr400 motor one day and do a little project.

[vroom4]

Originally posted by 400eXr1d3rZ
Does it have kickstart? Or electric? I dont quite understand what you mean


I might get a xr400 motor one day and do a little project.

Its a kickstart

To reexplain the problem.

With the valve cover off i can turn the motor over and it is smooth

But when i put the valve cover on and kick the motor over it gets stuck. and i have to repeatedly keep tryin to push the lever down and it eventually goes. My timing is also off one notch.

[400eXr1d3rZ]

For all our friends that don't understand.


It is a 250x, yes it has kickstart. And this is what he means. When he trys to kick start it, the Kicker doesnt budge, like the kicker is locked up.

[plkmonster2]

Yeah, it must be a 250x, if it kicks forward. The cam could be wrong, or it could be the wrong valve cover.

[vroom4]

should the front rocker arm be very tough to move? the rear one is very bouncy and can flick and move. the front however is very resistant. Im wondering if its getting stuck when im tryin to kick it over.

Anyone know a good place to buy rocker arms and how to change?

[plkmonster2]

They shouldn't move too much. Just tick. If you can push the valve down, the spring is shot.

[vroom4]

well wtf would cause my motor not to be able to turn over when the valve cover is on. Its gotta be the rocker arms or the cam pushing up wrong.

I can kick it over every like 3rd of 4th try but the other times its just like stuck.

[GPracer2500]

Originally posted by vroom4
well wtf would cause my motor not to be able to turn over when the valve cover is on. Its gotta be the rocker arms or the cam pushing up wrong.

I can kick it over every like 3rd of 4th try but the other times its just like stuck.

Are you sure you're not just feeling the resistence of TDC on the compression stroke? The resistence felt through the kicker will vary depending on where the piston is in its stroke....

[vroom4]

Originally posted by GPracer2500
Are you sure you're not just feeling the resistence of TDC on the compression stroke? The resistence felt through the kicker will vary depending on where the piston is in its stroke....


im 17 and weigh 200 lbs. If its so compressed that i cant kick it over...DAMN thats a motor.

Its gotta be something with the cam or rockers.