jetting

[Eddie]

Well since I had a slightly lean condition before i put the newtronics kit on, and now after putting the kit in the bike seems really lean! maybe cus the timing is right, or my luck its off, or because i have better spark now? not sure but anyway I went ahead and put the next size bigger pilot jet, I know alot of people say the main but I figure i would start with the pilot 1st and see what happens, and now the bike actually smokes a little at idle, it never really smoked before and now it does so hopefully that is a good sign and not a rich condition, just wanted to see if anybody changed their pilots on the gt750? i have rode the bike 2 times and I think it actually feels pretty good but I have not opened it up yet so we will see. The stock pilot is 47.5 on mine and i went to a 50 , I also went back to the b6es plugs which are what it calls for and it seemed to do better, i just dont like a hot plug but it runs better....so anybody ever just change the pilots and not the mains? I have on other bikes but those were 4 strokes not two strokes, im pretty good at getting the jetting right on a four stroke but there is so many variables on the 2 stroke, like what oil you use, oil pump adjustment and so on,and its kinda hard to tell what condition you have when riding (at least for me) cus its a 2-stroke she seems to run pretty good no matter what jetting i do, so far

[tz375]

BS40 CV carbs are a little more complex to set up because slide position is determined by operating conditions rather than twistgrip.

Mine runs slightly lean at the bottom end with stock pilot jets and chambers plus UNI filters and then goes rich and lean at the top end. Arguably, it "feels fine" but the air:fuel numbers are all over the map. I tried larger main jets, different needle clip positions and larger needle jets and race gas. I need to take more time to analyze the data and see if I can work out exactly what it needs.

In your case, I'd raise the needles one clip position and see how that works on the street.

[Eddie]

Thanks for the info, I cant believe how hard it is to get the right jetting, wow, and mine was also lean at idle and low speeds, now with bigger pilot it is not, i have stock jets and one size bigger on pilots with the stock air box, which is wierd because im at 4,000.00 feet and the book says to reduce jetting by 5% for every 3,000 feet above sea level , also i have my needles on the second to last slot, so i can raise the needle one more time before i have to go to larger jets....

[tz375]

The fun thing with CV carbs is that both needle jet and needle and the main jet change the whole fuel curve.