I just finished installing and testing the BK Mod on my 2000 YZ 426. The mod was relatively simple to install, but the results were not overwhelming. I believe the bike revs a little quicker and cleaner, but I have not completely removed the hesitation when wicking the throttle.
I am able to get at the new spring/screw I installed to adjust the pump spray duration without taking the carb off the bike. I initially set my duration to around .5 seconds (.3 is what Brian Kinney says is optimal) and put the carb back on the bike. My stock duration was probably at or around 1.5 seconds. When I first started the bike and took it for a spin, I noticed very little change. I came back and turned my new adjustment screw in 1/8 of a turn and rode again. I can feel the response getting a little better, so I adjust twice more, an 1/8 of a turn each time. I can now feel a noticeably better throttle response and the hesitation off bottom has been significantly reduced but it has not disappeared completely. With each subsequent 1/8 turn I can no longer feel any gain in performance. When I took the accelerator pump cover off the bike, I noticed my adjustment screw was against the pump cam, in effect I had disabled the accelerator pump. I didn't notice any major difference in performance during my last spin, so how do you know when your accelerator pump is working or not ?? I backed the screw out a few 1/8's until I found my peak performance again and left it there. How do you know when the accelerator pump is not working and what effect will this have on the bike ?
At one point in my garage I left the bike idle on the stand while I was adjusting the new screw and at the same time I was wicking the throttle on the bike to test response. I may have been doing this for 2-3 minutes, and the next thing I know I have anti-freeze coming out the over-flow. Does reducing the amount/duration of gas from the accelerator pump cause the bike to run lean and therefore too hot ?? Or was it just that I was wicking the throttle too long while the bike was idling and standing still ??
I've also heard people say to try the 01' Needle in the 00 Model. How is the 01' needle different than the 00 model ?? Has anyone tried this by itself or in combination with the BK mod ?
I am able to get at the new spring/screw I installed to adjust the pump spray duration without taking the carb off the bike. I initially set my duration to around .5 seconds (.3 is what Brian Kinney says is optimal) and put the carb back on the bike. My stock duration was probably at or around 1.5 seconds. When I first started the bike and took it for a spin, I noticed very little change. I came back and turned my new adjustment screw in 1/8 of a turn and rode again. I can feel the response getting a little better, so I adjust twice more, an 1/8 of a turn each time. I can now feel a noticeably better throttle response and the hesitation off bottom has been significantly reduced but it has not disappeared completely. With each subsequent 1/8 turn I can no longer feel any gain in performance. When I took the accelerator pump cover off the bike, I noticed my adjustment screw was against the pump cam, in effect I had disabled the accelerator pump. I didn't notice any major difference in performance during my last spin, so how do you know when your accelerator pump is working or not ?? I backed the screw out a few 1/8's until I found my peak performance again and left it there. How do you know when the accelerator pump is not working and what effect will this have on the bike ?
At one point in my garage I left the bike idle on the stand while I was adjusting the new screw and at the same time I was wicking the throttle on the bike to test response. I may have been doing this for 2-3 minutes, and the next thing I know I have anti-freeze coming out the over-flow. Does reducing the amount/duration of gas from the accelerator pump cause the bike to run lean and therefore too hot ?? Or was it just that I was wicking the throttle too long while the bike was idling and standing still ??
I've also heard people say to try the 01' Needle in the 00 Model. How is the 01' needle different than the 00 model ?? Has anyone tried this by itself or in combination with the BK mod ?
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