426 won't start


12 replies to this topic
  • niterider40

Posted September 14, 2009 - 11:27 AM

#1

It started for about 5 seconds yesterday and sounded good till it died, I have a 450 auto decomp cam and a 12 oz flywheel. I have a 172 pilot and a 42 main and at 500 ft elevation and around 50 degrees. I dragged it around the block with my car and it still won't start. I did try the hot start button after I couldn't get it started with the choke. I have been experimenting on the best starting techniques for this bike which I haven't had very long. I wonder if it jumped timing? Any ideas??

  • got5steelman

Posted September 14, 2009 - 12:11 PM

#2

Did you try changing the spark plug?

  • niterider40

Posted September 14, 2009 - 06:07 PM

#3

humbled by my silly sparkplug, now it runs better than ever with the bigger jets and the new iridium sparkplug

  • DeeCee

Posted September 14, 2009 - 06:09 PM

#4

Check the sticky's for the starting video. Essentially the procedure from cold is choke on, two twists of the throttle, take your hand off the throttle, kick and it should start. The key is not to twist the throttle while kicking which is why many posts on this subject say take your hand off the throttle completely. My YZ400F starts first or second kick using this procedure.

If the bike does not start readily using this procedure your probably have a carburettor problem.

As for your current problem, try changing the spark plug as the previous post suggests. If still no start you will have to go back to basics - check spark, check timing, etc

  • milk

Posted September 14, 2009 - 06:19 PM

#5

incidentally what is the part number for an iridium spark plug for a 2002 yz426f? i take it i can pick one up pretty much anywhere?

  • johnnyuterus

Posted September 14, 2009 - 08:20 PM

#6

cr8e and ask for the iridium, they do not have a specific part # for iridium you must ask for it.

Try the CR8EK which has 2 electrodes and seems to run better.

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  • grayracer513

Posted September 15, 2009 - 08:26 AM

#7

There is indeed a specific NGK part number for the iridium plug for a YZF. It is the CR8EIX. It has a standard electrode pattern and an iridium center electrode. The advantage of this is that it allows a stronger spark with less energy, which in turn aids in starting the engine at the very low speeds produced by the kick starter.

  • milk

Posted September 15, 2009 - 01:12 PM

#8

There is indeed a specific NGK part number for the iridium plug for a YZF. It is the CR8EIX. It has a standard electrode pattern and an iridium center electrode. The advantage of this is that it allows a stronger spark with less energy, which in turn aids in starting the engine at the very low speeds produced by the kick starter.


where do i get one? like can i pick one up from autozone or what? thanks :busted:

  • grayracer513

Posted September 15, 2009 - 01:15 PM

#9

Autozone? I doubt it. A motorcycle shop would be a better bet. You can also get them from Amsoil.com.

  • milk

Posted September 15, 2009 - 01:21 PM

#10

yeah i'll just check at unlimited cycle center... they're closer anyway. sorry for being a tard but i usually order my stuff but i think i could use a fresh plug.

  • niterider40

Posted September 16, 2009 - 04:43 AM

#11

well, after riding my bike for a few hours it seemed to run well. I came home and the next day started again for 5 seconds and it died with the choke on. Now it won't start. I cleaned the carb, maybe yet another plug? could it have jumped timing with the auto decomp cam?

  • Forddriver45

Posted September 28, 2009 - 11:17 PM

#12

id try the plug my 426 is bad about plugs fouling idk y tho ive check carb jeting and i finaly got it by using a hoter plug.

  • rufusz

Posted September 29, 2009 - 02:01 AM

#13

maybe your idle mixture is too rich. try to lean it until you have some decel popping or starting issues and than back it until these disappear.
i've also tried the iridium plug couple of years ago, but didn't see any difference. I use the same normal ngk plug for almost a year now and it starts just like a charm, sometimes I don't have the power/mood/right position to properly kick the kickstarter, I'm just "pushing" it down and it still starts.





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