Jetting help

Hey guys i read some threads but im still kinda confused. Anyways i thought i'd post my setup and stuff so i can get a better idea. I got a 01 YZ426, White brothers exhaust (R4), and i just put the Quickshot on. I did the AP mod (just put on o-ring around the lever and screw) and was taking a look at the BK mod but when i turn the lever it stops where if there was a screw there in the first place so i really dont see a need to do it?

Jetting is stock on this thing, 162 main jet, 42 pilot jet, the jet needle is in the middle. I have the bog and also some sputtering in mid throttle, i think its just dirt im gonna clean it out. Any advice for me? I was thinking about a 165 main but would like some input, any would be helpful. Thanks in advance.

I had the same exhaust on my bike. I had a 170 main jet and a 48 pilot and it ran perfect. I also put the Boyeson AP cover on. My bike is a 2000 YZ426.

If you used the o-ring to "wire" the AP then you will not be able to use the BK mod. These two mods won't work together because the BK would then act just like a throttle stop screw. The BK mod allows you to adjust the squirt duration, IE how far the AP shaft is turned. The wire mod makes the AP squirt as soon as the throttle is twisted and keeps squirting until the throttle stops. I think you should consider taking your o-ring off and doing the BK mod instead since these bikes don't have a leak jet and there is not any way to adjust the volume of the AP squirt. The problem originally was too much fuel anyway. Just my 2c. Hope this helps.


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