Jetting advice needed!! YZ426

[yzfrider389]

2002 YZ426 with an Arrow full exhaust system and K&N High Flow air filter.

Pilot jet - 42 (stock)
Needle clip position - 5 (stock is 4)
=Too rich (black spark plug) -- bike farts and runs poorly from 1/4 - 3/4 throttle

Pilot jet - 42
Needle clip position - 6
=Too lean (white spark plug) -- bike farts and runs poorly in the same range

Am I interpreting the spark plug color correctly? What else would you guys try? Different needle size? Take it to a professional? Any ideas on cost?

Thanks in advance

[pwpwnage]

ummm what size is the main jet?

[yzfrider389]

not sure. at least 1 size bigger than stock. will ck tomorrow