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hard to kick over

By boats203steveb,
in YZ400F/426F/450F/450FX

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boats203steveb

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after trying to adjust the valves my self ,I ended up bringing it to a mechanic. he said i had the intake cam a tooth off. checked comp checked leak down the were all good.Now the bike is real hard to kick over,its real hard to just get past top dead center. then the rest of the stroke is normal. Does any one have any suggestions.after you start it if it does it seems to run fine.

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2wheels-drz

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Why bother getting it over TDC? Just kick it.

Am pretty sure he means that it is not auto-decompressing. rest of the stroke is normal, and then locks near TDC, i.e. bringing up on compression. My 04 does this from time to time, not a clue why, bike still runs perfect. I would reconmend that when the kick starter locks, not to jump on it to get it to go past this could damage the kick start mechinism, but rather you stick you bike is gear and rock it past TDC, then kick it over....tis wat i do, as it only happens the odd time with mine.

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Grand Master

grayracer513

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The occasional failure to decompress properly is generally associated with a stall condition. If the engine stalls against compression, which it's actually pretty likely to do at low rpm under a load, it may come to a stop so abruptly that the decompression mechanism doesn't have a chance to reset itself before the engine stops. This will trap the decomp pin in the retracted position, and the flyweight return spring simply isn't strong enough to force the exhaust valve off its seat. The cure is either to slowly push it through compression, or to put it in gear and rock the bike backward away from the compression stroke, allowing the auto decompressor to fall back to its starting mode.

If, OTOH, the bike is now consistently very hard to turn over, and it's just since the work was done, there may be a problem with the auto decompression unit, or the timing of the exhaust cam. If that's the case, you should talk to the service manager.

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  • 6 months later...
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Aka.Goose

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Sounds very close to what I have the bike in the shop for now...My problem didn't happen after a stall, but rather after the bike was running normal all day, shut down normal, then upon trying to start again, wouldn't start and had a very similar "hard to kick" problem (and the cam sprocket was off by one tooth)...I had thought too, that it must be a problem with the auto-decompression, but the shop said it was due to a faulty cam tensioner...I'm having the tensioner and cam chains replaced, I'll post results as soon as I get it back...

Here's my similar thread:

https://www.thumpertalk.com/forum/showthread.php?t=625947

Oh also during inspection, the mechanic set the tooth correctly, and then it started fine, ran for 2 minutes, then backfired and shut down...When he opened it back up, the cam sprocket was once again off by one tooth...

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Grand Master

grayracer513

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If the exhaust cam were to become one tooth advanced, the auto decompression mechanism would be well out of time, and close the exhaust valve too early, resulting in a hard to crank engine. But it would be that way all the time, not occasionally.

The AD flyweight will disengage the mechanism at only about 6-700 RPM, and it is actually possible to kick the bike fast enough to deactivate it, making it as hard to start as if it did not have the system at all. This is why smooth, long kicks work better than hard fast ones.

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  • 11 months later...
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Kirkster

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So what is the answer if this happens with a Rekluse clutch installed on the bike?

You have to get the kicker out and whack it till you can get the piston to move a bit.

i have this happen on occasions when I shut it down and it does not want to start with the button. It also does not want to kick at first either. Having the Rekluse just compounds the issue as you can't bump it in gear to move the piston past the sticking point...

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  • 3 years later...
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Blaster21996

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So what is the answer if this happens with a Rekluse clutch installed on the bike?

The kind of clutch has no bearing on this issue.

Well...now I have this problem. Yesterday i stalled my bike after running for 3-4 minutes. I went to kick it, and the kicker was rock solid not moving. I rested my foot on the kicker and it slowly rotated down.....this usually fixes the AD lock issue....this time however. It did not work, the kicker is impossible to kick through. From reading threads here...this problem may be the timing chain jump on the exhaust cam.

Speculation?

Edited by Blaster21996
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