BK Mod

Just wondering what kind accelerator pump duration other people run? Also, what jetting changes if any have others used? The pics on the motoman site show the screw a long way away from the acc pump stop, but the text says about 0.3 sec is the desired duration. :)


The squirt should be less than a second. 1/3 to 1/2 are talked about alot. The only way to tell the difference would be to film it and count frames. Mine is about 1/2 second and has no bog.

Thanks, i'll try a longer duration when i remove the carb to do the Jamesnow mod.


The timing of this whole thing is really tricky. Make sure that you have the timing set correctly! The only way I could tell if the timing was correct was to set it to where I could see that the slide was wet, ie the squirt hitting the slide. Then wipe the slide, 1 sixteenth of a turn until it was missing the slide. After that, the duration was simple on my 00 (the diagaphram is a bad one for that year).

Alternative to the BK mod, you could order up the '02 diagaphram. I put a tech post in the YZ forum with the numbers, duration, etc from the 04 tech seminar book.

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