2009 yz450f Top Dead Center Problem!


3 replies to this topic
  • vic2340

Posted December 01, 2012 - 10:03 PM

#1

[font=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif][size=3]Hello Everybody, I have recently purchased a 2009 yz450f for quite a good price. (Completely stock)I knew their would be issues but me fixing many bikes before though it wouldnt be a big deal. I noticed the bike poping badly and it had extreme bog. I Set the carb back to stock jetting this didnt fix the problem so from their I knew it was the valves. I know how to get a bike to top dead center, its no big deal but for this bike it was messed up .The cam markings were horizontal in the correct position when the bike was at tdc. However the markings on the cdi side rotor were quite off. I knew the rotor was off and not the cams because when I stuck a metal rod in the spark plug hole it stood highest when the cams were in sinc and not when the cdi/rotor markings were aligned. Now my questions are #1 does the rotor on the cdi side have to be aligned with the cams in order for the bike to run well? The valves shims by the way are not correct I need to re shim them (I did the feeler gauge measurements). #2 Does the rotor send magnetic signals to the cdi at certain rotational angles? and #3 can I fix this without splitting the case? [/size][/font]

  • grayracer513

Posted December 01, 2012 - 10:23 PM

#2

If the flywheel is indexed wrong (real TDC is not where the timing marks say it is), it's a near certainty that the key that indexes the flywheel is sheared or missing due to improper assembly. It can be repaired by removing the stator housing (left side crankcase cover) and pulling the flywheel. Look for serious damage to the taper surfaces. If they're too screwed up, you won't be able to reuse that part.

The ignition is triggered by a small induction coil that sends a signal to the ECM when a lug on the outside of the flywheel rotor passes it. The ECM uses that to determine crank position and engine speed, so it's quite critical that it's in the right spot.

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  • vic2340

Posted December 02, 2012 - 10:00 AM

#3

Thank you very much for the response. Now can I use a flywheel puller from an 03 crf450r on this bike? are they the same?

  • vic2340

Posted December 02, 2012 - 05:57 PM

#4

Never mind I cant use a crf450's flywheel puller I need o buy a special one. Anyways thank you for the info, very helpful!





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