BK Mod to a 2002

I did the BK Mod to my 2002 this past weekend. I have stock jetting at 300' above sea level and the air temp. was around 50. Before the mod there was very little bog and it was only when cracking full throttle off idle. The squirt length was at 1.4 sec. and the timing seemed to be right on. I changed the squirt length down to .4 and made no other changes. When I tested this setup, I found a big bog off idle. So much that it would stall the engine. As I turned out the newly installed screw to increase the squirt length, the bog decreased. I found that no mod at all gave the least amount of bog. Any thoughts as to why this mod had a negative effect on my 2002.


Brent,Im doing my 2002 426 tuesday I would have to say your jetting is to lean,Maybe the 2002 bike doesnt need the BK.I will let you know how mine turns out,I will be rejetting mine,168main 48pilot maybe even richen the needle.

I've heard that the Bk mod has and has not improved the 2002. If your squirt was at 1.4 and you reduced it, you should go one up on the pilot jet to compensate for the shorter squirt. That should cure the bog. Fine tune with the fuel screw.

My 2001 squirt was at almost 3.5 seconds. There are some who say their 01 squirt was at .5 seconds. It appears that every bike is a bit different on duration.


Adjusting the squirt duration alone without readjusting the timing will not do the trick. Adjustments to the squirt duration screw that you installed directly affect the timing.

I would be willing to bet that your slide is close to a 1/3 of the way up before your pump sprays. Not quick enough = bog.

Adjust the spray so that it begins just as the slide clears its path. I'm no expert on the subject, but that worked very well for me. I have a 2001 and after I performed the mod, I had the same bog off idle.

It is a combination of the right jetting, spray timing, and duration. You'll be lucky if you get it right the very first time. Have patience and play with it. You'll be happy with your results.

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