Jetting issue with a 02 YZ 426

Im having some jetting problems with my 02 426. It blubbers badly just above quarter throttle. Originally I thought that it was the pilot jet so I changed it to a 40 from the stock 42 and dropped the needle one notch. I also installed a Ty Davis fuel screw. It still ran just as bad as before. The following mods were done to it: 01 YZ 250 2 stroke airbox and side panels and a FMF Q series spark arrestor. The main is still stock as is the starter jet. Any ideas?

Thanks, Rob

It would be the needle that affects that throttle setting. I would try to raise it up. Is everything spotless? If you went from a 42 to 40 AND dropped the needle it is probably starved for fuel. Always easy to find out. I would go back to what worked last and start over.

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