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madmotocrosser

yz426 motor/hot start questions

2 posts in this topic

First off not experianced with bike motors but recently put 00' yz426 motor in a quad frame. Motor has 444 kit with decompression hot cams and mild head work. Bike was built from ground up past few months but shop bike was at ran into trouble. Bike was ran as required to break in hot cams, but other day when going to test ride is when trouble started. Bike would start great, but when hot it was a no go. Now I do not have a hot start on this bike and was told by others this could be my problem but looking for help on here.

For test ride when bike started cold jets were 58 pilot, 205 main, and 90 starter. Bike did show to be a little lean and changed main to 208.

Now after changing and trying to start several days later bike will not fire when cold either. Did bump start bike and ran excellent but just not starting either hot or cold.

Looking for help on the above and how to add hot start with lowest cost involved. Now carb is a keihin ( size - don't know), and was told it was from a yz. I have seen pics where this is supposed to be but does not look like carb was made for one. Is this something that is possible to add to my carb then?

Other notes is for plug I am using NGK CR8E and running 110 gas with high compression pistion. Really a newbie when it comes to this motor and any help would be greatly appreciated, thanks.

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Either your jetting is way out the window or you are not running the FCR type Keihin carb.

Drop the pilot to a 45-48, the main to 168 and try that...

I surprised it started at all.

Big bore kits dont need that much jet. And the cam just makes it worse. Then you throw the 110 gas which probably has a lighter specific gravity, Im almost surprised you didnt ask about the giant billowing black smoke belching out the pipe like a diesel.

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