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desertwheelspin

Kick start stuck, piston still moves

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Hey everyone,

Been riding for 10 months and appreciate all the contributions on tt. My 08 yz450 stalled after a small jump while in first gear, clutch pulled in. Went to start it. On kick, stuck at the top of kick. Have read many posts on this but have something new to offer from what I've read. Here's a rundown on what's going on and history:

Bike has low hours, well maintained

Good oil level upon stall and inability to kick starter down

We rode several hours of single track on a cloudless day, with a high of 93 degrees

With clutch in can roll back and forth

Rolls freely in neutral

Rolling backwards in gear hear/feel compression once! Then things get stuck, seemingly at top dead center

After rolling back and hearing compression, try kickstart and will kick half-way down kick,

Release from that kick and the next kick is stuck at the top again.

Checked oil filter. No copper or brass colored metal. A few large silver pieces but not many. Have not experienced this before.

Very confused, and I know the community as a whole may have some wisdom to share. Thanks in advance. Today hit the biggest jumps so far.... Not the small one referenced in the bike problem.... Psyched..... Want more and as soon as possible!!!! Thanks

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The problem is probably in the top end or the kick starting gears your gonna have to check them both and see is start with the kick starter gears

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Do a quick check, put the bike in gear, pull the spark plug, and spin the wheel. If you can get a complete rotation of the engine, check the kick starter gears. If you can't, or you hear something clanging around, you probably broke a valve and it's keeping the engine from going past TDC.

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Cam timing needs to be checked.  Your chain has likely failed (binding links, "kinking") and let it slip time when it kicked back as it stalled. 

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Thanks for the reply. What will be the easiest to check? Top end or kick gears?

the kickstart gears will be the easiest but you will have to check both and maybe replace some valves

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I'm not sure how YZ450's work where you live, but here, pulling the tank, top motor mounts, and cam cover is lots simpler than draining the oil and coolant and removing the right side case cover.

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Removing right side cover is easier than ordering a whole lot of gaskets to check the top end because the right side case gasket is a lot of times reuseable

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Ok, so I've done both now.  After removing the the cam cover everything was looking good in there, cam chain seemed fine and no signs of any chipped metal.  After removing the side, clutch basket and the such, all gear were in good order and kick starter gear and spring moved smoothly.  A friend thins possibly a problem with a valve seat?  Any thoughts from anyone?  Thanks.

 

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Ok, so I've done both now.  After removing the the cam cover everything was looking good in there, cam chain seemed fine and no signs of any chipped metal.  After removing the side, clutch basket and the such, all gear were in good order and kick starter gear and spring moved smoothly.  A friend thins possibly a problem with a valve seat?  Any thoughts from anyone?  Thanks.

 

Did "everything" include the cam timing?

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