2015 yz450f wierd kicking issue


1 reply to this topic
  • ryanrambo24

Posted August 18, 2016 - 04:07 AM

#1

just shimmed valves on a 2015 yz450f and after reassembling the valvetrain. the exhaust timing mark is not exactly level with the plane of the head. its about 1/8" to 3/16" above. went one tooth back and it goes below the level of the head. the intake and crank marks are spot on. everything starts and runs normal.

only concern is that when kicking you must go thru the process of getting the motor to top dead center. if you kick it like a 2 stroke it will violently kick back every 3 kicks or so. And it didn't do this before shiming the valves. Left intake was out of spec and was shimmed.

as far as my expierence level I have done all my own top and bottom end rebuilds minus cutting valve seats.shimmed plenty of valves and suspenions work. on all my bikes for the last 20 years. this is just the first time working on this specific bike and just want to know if im missing something.

thanks

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  • grayracer513

Posted August 18, 2016 - 06:29 AM

#2

only concern is that when kicking you must go thru the process of getting the motor to top dead center. if you kick it like a 2 stroke it will violently kick back every 3 kicks or so. And it didn't do this before shiming the valves. Left intake was out of spec and was shimmed

 

Getting the engine to TDC is not part of the process.  Push the kick starter up against the compression stroke and kick it, that's it.   The reason it randomly kicks back when you kick from a random position elsewhere in the cycle is that you will, on occasion, have the engine come to a stop just before TDC and just as the ignition fires.  That will rotate the crank backward under power.  When you kick from the start of the compression stroke, you force the crank through compression, past the ignition point, and over TDC into the power stroke to get it moving the right direction.







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