YZF 450 Kick start trouble


17 replies to this topic
  • Dutch646G

Posted November 27, 2009 - 01:20 PM

#1

I have a 08 YZF450 yestrsday I tried to ride and the kick start was locked up. We tried to roll start it and it acted locked up. A friend recommended putting it in gear and pushing it backwards. It did free up the kick start. It would kick but it still would not start. We tried pull starting it and still nothing. Today I pulled the plug and turned it over with no problems and pulled the oil filter and found no metal, so the motor would appear to be ok. Any suggestions on what could be the problem.

  • grayracer513

Posted November 27, 2009 - 08:54 PM

#2

Check the valve timing.

  • MotorMan1515

Posted November 28, 2009 - 07:20 PM

#3

Valve timing could show why you couldn't kick over your bike. However, if you can kick it over with the spark plug out, that throws the valve timing question out. I would start by checking your valve clearances, if the valves exhaust valves are loose, it would make the engine hard to kick over (however I doubt that's the case, unless someone adjusted the valves recently, and adjusted them too loose). Another thing that could cause the bike to not kick easily when the plug is in, is the automatic decompression. If I were you, the auto decompressor is the the first thing I would look at, then check the valve clearances. If the valve timing was off to the point where you can't kick it over, it wouldn't kick over when the spark plug was out either, unless if the timing was off and you bent the valves when you were trying to get it to turn over.

  • grayracer513

Posted November 28, 2009 - 07:33 PM

#4

Valve timing could show why you couldn't kick over your bike. However, if you can kick it over with the spark plug out, that throws the valve timing question out. .... If the valve timing was off to the point where you can't kick it over, it wouldn't kick over when the spark plug was out either, unless if the timing was off and you bent the valves when you were trying to get it to turn over.

That is simply not true.

If the exhaust cam were to become one or two teeth advanced, the timing of the decompression pin (which is entirely dependent on cam timing) would be such that the exhaust valve lifted off it seat by the decomp pin would reseat too early, resulting in less than a sufficient amount of compression being released. At this timing, however, no valves would interfere with the piston, and the engine would appear to turn over normally with the plug out.

http://www.thumperta...171#post6849171

  • MotorMan1515

Posted November 28, 2009 - 07:39 PM

#5

I stand corrected grayracer513. Sorry for the inconvenience. Only thing I can suggest when you have checked that is to make sure that you have the correct cam chain tension.

  • Dutch646G

Posted November 29, 2009 - 06:56 PM

#6

Ok I pulled the chain tensioner And checked it. It seems to be working right i pulled the plug again to try to see if fuel was in the cylander causing it to hydraulic and while i was running it through the kicker locked up again! I have no clue what could be the problem I guess its off to the shop. I am not comfertable pulling the Valve cover off and exploring the timing possibilites. Maybe it is something in the transmission?

  • grayracer513

Posted November 29, 2009 - 07:39 PM

#7

Ok I pulled the chain tensioner And checked it. It seems to be working right i pulled the plug again to try to see if fuel was in the cylander causing it to hydraulic and while i was running it through the kicker locked up again! I have no clue what could be the problem I guess its off to the shop. I am not comfertable pulling the Valve cover off and exploring the timing possibilites. Maybe it is something in the transmission?


Please tell me you did not turn the engine over with the tensioner removed. :banghead:

NEVER do that. The engine WILL jump time immediately. Comfortable or not, you're stuck with pulling the valve cover off now. Whatever else you do, DO NOT try to turn it any farther.

Once you get in there, check the timing chain. ANY stiff links indicate the chain was at fault to begin with.

  • Wes Woodin

Posted November 30, 2009 - 03:52 PM

#8

I have a 08 YZF450 yestrsday I tried to ride and the kick start was locked up. We tried to roll start it and it acted locked up. A friend recommended putting it in gear and pushing it backwards. It did free up the kick start. It would kick but it still would not start. We tried pull starting it and still nothing. Today I pulled the plug and turned it over with no problems and pulled the oil filter and found no metal, so the motor would appear to be ok. Any suggestions on what could be the problem.


My 08 did the same thing. All I did is put in gear and roll it back and forth, then it freed up. I always figured it was the gears on the kick start shaft locking up. It didn't happen all of the time so I figured it was nothing major. :banghead:

  • grayracer513

Posted November 30, 2009 - 04:15 PM

#9

My 08 did the same thing. All I did is put in gear and roll it back and forth, then it freed up. I always figured it was the gears on the kick start shaft locking up. It didn't happen all of the time so I figured it was nothing major. :banghead:

That sounds like a trapped AD pin, which can easily happen when the engine stalls suddenly, but is completely transient:

http://www.thumperta...979#post5314979

This sounds like it jumped time, to me.

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  • Wes Woodin

Posted November 30, 2009 - 04:52 PM

#10

That sounds like a trapped AD pin, which can easily happen when the engine stalls suddenly, but is completely transient:

http://www.thumperta...979#post5314979

This sounds like it jumped time, to me.

Actually it would happen when I was just trying to start it. Never did I stall it then try to kick it over and it lock up. It was weird. My 06 didn't do it, my 09 didn't do it. Only my 08, and it was so irritating. The first time it happend I thought it was a major problem. I just put in gear and rolled it back and forth then it would start. Maybe it had a broken tooth on the gear.????? Never saw metal or broken piece in the oil. Who knows. I sold the bike and got an 09. It never was a major problem to me though.

  • Dutch646G

Posted December 16, 2009 - 07:39 PM

#11

Just got it back from the shop.The cam chain was stretched out so bad it wouldnt adjust anymore. They changed the cam chain and adjusted the valves and now its fine or so they say. I fell off my roof and broke my arm so I cant even look at it. But thats the story

  • FinchFan194

Posted December 16, 2009 - 07:50 PM

#12

How'd you fall off if you don't mind me asking?

  • grayracer513

Posted December 16, 2009 - 07:55 PM

#13

My money's on he lost his balance. :moon:

  • FinchFan194

Posted December 16, 2009 - 08:02 PM

#14

Nooo really? Fine I wanted to know what he was doing. . .I assumed he was putting up Christmas lights is all. Happens a lot this time of year.

  • grayracer513

Posted December 16, 2009 - 08:42 PM

#15

I don't see how that keeps the thread on topic, though. :moon:

  • FinchFan194

Posted December 16, 2009 - 08:50 PM

#16

I don't either. . .it was a quick question not meant to create 5 posts.

  • mxmaddman

Posted December 17, 2009 - 03:20 PM

#17

Glad to hear its fixed. FYI next time its locks up dont force it or pull start it, you might not end up so lucky. that could have cost hundreds of dollars and a new head if the timing was off far enough. Also replace that chain at least annually.

  • Wes Woodin

Posted December 19, 2009 - 08:15 AM

#18

thank goodness it wasn't catastrophic.





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