Cold Weather Riding '00 YZ 426

Does anyone have an idea for jetting my bike. The bike is stock except for the PMB endcap with silent insert. The temp is roughly 40-50 degrees.

I have a 00 426 and I did the BK mod and ended up putting in a 168 main jet and a 45 Pilot I put in needle from the 2001 yz426 and put it at #4.

I have a 00 426 and I did the BK mod and ended up putting in a 168 main jet and a 45 Pilot I put in needle from the 2001 yz426 and put it at #4.

Was this for temps around 40-50 degrees?

Come on, someone has to know what jetting I need. Please help.


Scooter made a good jetting suggestion for your bike at cooler temperatures, yes that would be for below 50F. The pilot jet and main jet are both richer than stock with these settings.


Ok I will give this a try. Thank you Scooter and James.

yes it works quite well in cold weather. I also put the fuel screw at 1 3/4 turns out.

Well I checked out Yamaha's website to look up the parts that I needed and there are about 20 different needles to choose from for the 2001 YZ426F. How do I know which one to pick?

I think that was OBEJP-


The last letter is P instead or R


Thanks all for the replys. I installed the 168 main and 45 pilot. I have only had a chance to run it for about 5 min in about 40 degree weather and it seemed to run great. I do not think that it poped even one time and still seems to rev quick. I did not get to install the '01 needle yet. I could not find a dealer that had one in stock but definatly plan on it. Again thank you.

Ran GREAT!! all weekend. It was nice to get it out for one last ride before the snow flys. Thanks again for all the help.

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