hard to kick over


18 replies to this topic
  • boats203steveb

Posted September 22, 2007 - 02:57 AM

#1

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.

  • grayracer513

Posted September 22, 2007 - 06:13 AM

#2

What year/model are we talking about?

  • rexbond007

Posted September 22, 2007 - 07:00 AM

#3

maybe over tightened the cam cap bolts? i did that once. after correct torque,

the motor turn over easier.

  • Dirtbiker05

Posted September 22, 2007 - 12:45 PM

#4

maybe over tightened the cam cap bolts? i did that once. after correct torque,

the motor turn over easier.


good suggestion. :thumbsup: :thumbsup:

  • boats203steveb

Posted September 22, 2007 - 01:04 PM

#5

the bike is a 2004 yz450f.

  • grayracer513

Posted September 22, 2007 - 04:09 PM

#6

Why bother getting it over TDC? Just kick it.

  • 2wheels-drz

Posted September 23, 2007 - 03:10 AM

#7

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.

  • grayracer513

Posted September 23, 2007 - 08:54 AM

#8

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.

  • Aka.Goose

Posted April 05, 2008 - 01:05 PM

#9

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:
http://www.thumperta...ad.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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  • grayracer513

Posted April 05, 2008 - 02:07 PM

#10

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.

  • Aka.Goose

Posted March 19, 2009 - 10:37 AM

#11

Almost a year later update:
No problems since replacing the cam tensioner and cam chains...

  • bmah

Posted March 22, 2009 - 01:06 PM

#12

Almost a year later update:
No problems since replacing the cam tensioner and cam chains...

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

  • grayracer513

Posted March 22, 2009 - 06:01 PM

#13

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.

  • Kirkster

Posted March 22, 2009 - 06:22 PM

#14

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...

  • Blaster21996

Posted March 22, 2009 - 07:28 PM

#15

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


I just installed the PRO in my 06. When this happens on my bike, I rest my foot on the kicker and apply steady pressure, after a couple of seconds it will slowly unlock, and I can go about my kicking again.

  • Blaster21996

Posted March 22, 2009 - 07:30 PM

#16

The kind of clutch has no bearing on this issue.


Yes it does, if you have the Rekluse, you can not put it in gear and rock it back and forth in order to reset the AD thingie ma-bob-er:smirk:

  • Blaster21996

Posted July 15, 2012 - 09:20 AM

#17

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, July 15, 2012 - 09:21 AM.


  • grayracer513

Posted July 15, 2012 - 10:26 AM

#18

From reading threads here...this problem may be the timing chain jump on the exhaust cam.


If getting it past the first compression stroke doesn't restore normal operation, then yes, cam timing is immediately suspect. If the exhaust cam gets to be one tooth early, cranking compression will increase dramatically.

  • Blaster21996

Posted July 15, 2012 - 09:01 PM

#19

If getting it past the first compression stroke doesn't restore normal operation, then yes, cam timing is immediately suspect. If the exhaust cam gets to be one tooth early, cranking compression will increase dramatically.


Thanks Gray :)





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