08 YZ 450 kickstarter "hanging" up?

[Monkeybutt2000]

Acts like it's stuck. You can kind've jiggle it around then it will kick through like normal. Where should I start to check? Never messed with the kickstart assembly before.

[Monkeybutt2000]

Finally got around to messing with this bike again. Come to find the intake cam is out of time. Would that cause this issue? I'm going to re-time the cams today and see what happens.

[grayracer513]

Commonly two things:

 

The cam partially seizes, which means head repair will be needed along with a new cam.  Or,

 

The timing chain has stiff links, which can cause the tensioner to allow slack to develop when the engine bounces back off the compression stroke while coming to a stop, or under a couple of other conditions. 

 

If the out-of-time condition caused the starter to feel as if binding, you may also have bent one or more valves. 

[Monkeybutt2000]

Well got the cams re-timed and buttoned back up. Kicked over just fine but cant get it to fire. About wore my ol 44yr ass out.  It's getting fuel but haven't checked spark. Time for a barley pop.

[knuckleduster271]

This is common on the yamaha 450's.

Most of the time its because the bikes running too rich.

My wr will sometimes stop at almost tdc when using the magic button, then if i go to kick it over it acts like its seized- normally a slight push forwardvwhile its in gear cures it.

Every one ive had has done this. Theres also a thread in the yamaha specific section of supermotojunkie.

http://supermotojunkie.com/showthread.php?136885-07-Wr450-Kick-Starter-lock-up

If you retimed the bike and are certain your marks are good make sure your lash shims are still in their buckets- ive seen them shift because a cap was lifted and cause a no start issue.

Edited February 1, 2016 by knuckleduster271

[Monkeybutt2000]

Well,bike had spark but was not getting fuel.  Was not squirting fuel when throttle was twisted, I was a bit perturbed when the manual said "remove rear subframe and shock" for carb removal.

[knuckleduster271]

Its not horrible, just remove the top subframe bolts and loosen the bottom two.

No need to remove it completely- it will hinge back far enough for the shock to come out the top.

[grayracer513]

The reason that I don't do it that way has to do with refitting the air box to the carb.  I unbolt the air box from the sub so that going back together, I can slip the air boot onto the carb completely unobstructed by any of the sub frame and clamp it there.  Then I slide the sub and rear fender back over the box and bolt it backup. 

 

What you find when you do this kind of thing for a living is that sometimes it's faster to remove 12 bolts and three things than it is to remove 4 bolts and work around stuff that's in the way.

[knuckleduster271]

The reason that I don't do it that way has to do with refitting the air box to the carb. I unbolt the air box from the sub so that going back together, I can slip the air boot onto the carb completely unobstructed by any of the sub frame and clamp it there. Then I slide the sub and rear fender back over the box and bolt it backup.

What you find when you do this kind of thing for a living is that sometimes it's faster to remove 12 bolts and three things than it is to remove 4 bolts and work around stuff that's in the way.

I know what you mean, those boots can be a real pain to get back on the carb....

I usually put a very small amount of sil glide(silicone grease) on the inside of the boot- it slips right on.

Edited February 2, 2016 by knuckleduster271

[grayracer513]

Then they can slip right off, too.  If you want to temporarily lube a rubber item like that, use Berryman's B12 carb cleaner, or similar.  Makes it slippery now, then dries away, actually helping the rubber seal to the metal.

[knuckleduster271]

Then they can slip right off, too. If you want to temporarily lube a rubber item like that, use Berryman's B12 carb cleaner, or similar. Makes it slippery now, then dries away, actually helping the rubber seal to the metal.

Been doing it for a long time, Never had one come off. The way the system is set up i dont really even see how its possible.

I use the silicone grease because it does dry over time and is harmless to rubber. Carb cleaner usually has some type of petro or solvent in it and will degrade most rubber or plastics.

Edited February 2, 2016 by knuckleduster271

[grayracer513]

So you're worried that a rubber boot attached to a carb and is frequently visited by gasoline back spray and vapors would be sensitive to petroleum products?  I see.

[knuckleduster271]

If you got fuel "frequently" spraying into your airbox then you have other problems...

And no, its not made to be submersed in solvent or raw fuel.

Ive seen chemical solvents turn even nitrile into puddles.

Edited February 2, 2016 by knuckleduster271

[Monkeybutt2000]

Anyways,no the subframe and shock removal wasn't hard,just unexpected. Yamahas engineers jammed everything as tight as they could on these bikes. Got the carb apart and soaking the jets so hopefully have it running soon. Next question would be,why did it jump time? Stretched cam chain? Bad tensioner?

[knuckleduster271]

Somehow i totally missed the post where you said it jumped time..

Did it run ok before aside from the kicker locking up?

Edited February 4, 2016 by knuckleduster271

[grayracer513]

 Next question would be,why did it jump time? Stretched cam chain? Bad tensioner?

 

See post number 3

[Monkeybutt2000]

Backstory: I bought the bike last Febuary,and never had the chance to ride it til several months later. Got it running,and it just shut off at idle. Not like it ran out of gas I mean immediate shut down.

[grayracer513]

$5 says it's a stiff chain.  Only takes a small handful of bad links.

[grayracer513]

If you got fuel "frequently" spraying into your airbox then you have other problems...

 

 

Do you know the term, "stand off"?  It refers to the NORMAL pressure reversal that occurs in the intake tract at low speeds and higher throttle openings because the intake valve closes well after bottom dead center, into the start of the compression stroke and carries atomized fuel out into the air stream outside the carb mouth.  It's not a "problem", it's normal behavior, and neither it nor an occasional dousing with carb cleaners will harm the boot in any way.

[Monkeybutt2000]

$5 says it's a stiff chain.  Only takes a small handful of bad links.

They're cheap enough,I'll get a new one. What about a manual tensioner?