Will BK mod fix miss at cruising speed when adding throttle??

With the new YZ timing, I have a slight miss while cruising off throttle, then putting the throttle on slightly. If I roll on the throttle stronger, it does not miss. Will the BK mod fix this? I have the impression that moving the needle to 3 postion reduces this problem, but, I like 4th position because the torque comes on so much faster. The bike gives much better wheelies in 4th position. Do I need the BK mode?? :)

drop the needle and be a good chap. preferably twice AND if you wanna pull better wheelies change "something else".


OK, I get the message. I will drop the needle :D

BTW, Sudco (Paul) apologized for sending me hex fuel jets instead of maj. He is sending me the correct 180 maj and 160 maj free of charge. The part numbers on the packing slip were correct, the guys at the warehouse messed up.

Do you think I should go with the 180 MAJ first or the 160 MAJ? I will put the needle back to position 3 while I am at it. See my sig. for current jetting. Thanks. :)

i would put the 160MAJ in after you've done a run with the #200 if you don't mind. it isn't very often we get confirmed test results here. i'd appreciate it anyway!

i think your MJ at #158 is about spot on at present but to feel a difference i would make test three to drop to #152MJ if you're above 3-4,000ft or possibly #155 .

the best test is to go;

1) as is

2) #200 to #160MAJ and check top revs overrun (frightening!)

3) try the #152MJ in which the midrange will coincidentally improve BUT YOU'RE NOT TESTING THIS!!!!!!! you're looking for maximum power. not the over rev-just max power.

4) depending on which MJ you end up with from (3) the needle can go down once and then possibly twice. this is a midrange (4th gear) test.

report back-love to know.



Lucky you, Taffy has taken an interest. I just finished my jetting with Taffy's help and the results are impressive. Like you I was raising the needle and getting improved acceleration but there issues at lower throttle stettings, not unlike yours. I started at EKN5 and ended up at EKN2 and I ride at about 500 feet, you should end up leaner than that. Explain the changes in performance as you change jets, follow his advise and you will find a happy place.

Good luck.


Thanks to Taffy, Hick, and others who have helped me.

I wish I could do more testing, but, my wife and my neighbors think I am nuts. I decided to take a shortcut and go straight to Taffy's jetting with my EKP at position 3, see my sig.. I rode it around the block and it runs good. No popping, starts good, idles good, reving in neutral sounds good, choke works good, good throttle response, I think the pilot circuit is spot on. Low end is really good. I get a very slight miss at high rpm, off throttle, when adding slight throttle to cruise. Nothing bothersome like before, I can live with that. I bet you if I go to EKP position 2 that will fix that. I am not sure I want to do that though. The top end full throttle, high rpm seems a little flat for YZ timing. I am not sure what to do to address that. Should I go to a 180 MAJ instead of the 160 MAJ? Or should I go from a 150 MJ to a 158 MJ? Right now I am doing my testing at 1900 feet. I normally ride at 3K-6K feet. :)

OK, decided to rejet. It was flat on the top end. Went from a 150 MJ to a 158 and from a 35 PJ to a 38 PJ. Also, reset the PAS to 65. Sig. is up to date. Did not have time to test, it is midnight here. I will test again tomorrow. Hope it cures the flat mid and top end. It should pull harder with the YZ timing.

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