does it help the performance to run stock 426 needle?

If I was to stick a stock 426 needle in my 99 WR400 with stock timing and pipe, and silencer with baffle out only would it help my performance???????????

Do not run YZ needles in a WR 400 unless you have the YZ cam timing!!! It will runf to hot and be lean on the bottom.

If you bike has YZ CAM timing and you want to try the 426 needle run a 48 PJ and no more than a 165 main jet probably a 162.

The needle will have more hit but as James and I have found its tricky to jet right around 1/8 to 1/2 throttle. I would recommend a EMN needle in the #3 from the top. But If you want to use the YZ needle go ahead but you will have to experiment to get it right.

I have developed a modified EMN that works excellent.

Clark

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