Mark ACC

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Just got done with the 3 year on/ off again xs street tracker project. Runs great but has a flat spot around 3K (I think when it's coming off the pilot and on the main), and I'm looking for some tuning advice. Particulars: 700 cc JE pistons and shell stage 1 cam from Hoos, Jetted it as per Mike Morse's advice, but I can't remember exactly what he told me. I know I drilled the slide, used his needle, made the main and pilot bigger (140??), used the stock BS32 carbs, 1-5/8" relativly long pipes with peak torque optimizers welded on the ends and torque cones (both from Mike Morse) and megaphones. Great air supply. I attached a motor pic if anyone has other questions. Any advice from the gurus in here would be hugely appreciated!

Mark C in Pittsburgh
IMG_1358.jpg
 
Well, you need to keep a list of the jetting installed in order to know where to go from there. But that being said, a flat spot usually indicates a lean condition. So, maybe you need to richen up the idle circuit a bit more. You can go up another size on the pilots or to make it just a little richer, reduce the air jet size one or two.
 
Well, you need to keep a list of the jetting installed in order to know where to go from there. But that being said, a flat spot usually indicates a lean condition. So, maybe you need to richen up the idle circuit a bit more. You can go up another size on the pilots or to make it just a little richer, reduce the air jet size one or two.
Thanks 5twins!
 
Well I for sure would try the Ole gggGary needle washer mod. "all" the BS34's come with that 3K flat spot from N/C ;)from the factory.
With that pill warm it will slide right down the needle install ONLY ONE washer, reassemble. a 3mm washer from the local hardware will do the job.
needle washer mod (3).jpg

If that's not enough, many of the BS34 carb kits come with 5 slot needles. But I have not tried them.
You might want to try not going WFO and use some wrist finesse through 3K that bigger hole may be popping the slide open a bit faster than the venturi suction can keep up with.
 
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