Yz426f help!!!!

3 replies to this topic
  • 426yota

Posted April 11, 2010 - 04:45 PM


2000 YZ426F HELP!!!! < SnakesRus > 04/11 17:43:15

My bike is impossible to start.....

I just put a new plug in it and adjusted my carb back to stock specs besides the idle screw, cause i need the bike running to get that right.

Ive heard it might need a valve job.

Ive also heard that it might need to be rejetted due to my FMF Powercore 4 exhaust.

It has great compression, its impossible to kick over at the top of the stroke and I know it gets spark because Ive got it started once and rode it around for a while. When I did ride it I noticed it popped when decelerating, it ran hot enough to start overheating (coolant was coming out of the over flow) and to start melting my side panel at idle (however it didnt have a heat shield like it is supposed to).

Any ideas..

  • trueweb

Posted April 11, 2010 - 05:35 PM


Start with the obvious. Is it getting fuel, spark and air? Check for spark, make sure the plug is getting wet and that you're air filter is clean and not over-oiled.

Next look at the carb. Pilot Jet and screw will affect start and idle. Not sure how the pipe affects this or what you should set them to, but that's the next place i'd look by setting it back to factory and seeing if moving it either direction changes anything (just figured this out helping to get a friends bike running). I believe running hot is also a sign of being lean, but I'm not sure how that relates to starting or idle since all those are different circuits in the carb. Time to do some research.

Checking the valves is not an overwhelming task or you can pay someone do it for you. Adjusting them is a different story. Buy the Motion Pro Tappet Feelers, they make the checking job a lot easier than trying to bend even narrow tapered feelers under the cams.

Good luck!

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  • buzzgrizz

Posted April 11, 2010 - 07:06 PM


check the valves, shim if necessary, if you cant shim them to spec then its new valve time.

  • 426yota

Posted April 12, 2010 - 10:29 PM


ok so i think i figured out the problem

To me, it looks like my cam sprockets are misaligned or they spun a little

Posted Image

The right cam gear looks to tilted just a little bit at TDC and the left one looks to be way off.

How can i tell if they spun versus someone just mis-aligning them on the last valve job?


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