OK here's the update!
Rich lent me a copy of his Mikuni manual and said to let everyone know what i learned, so here it goes.
1. when i swapped to the wider OD needle, i wasnt really changing much- the needle OD only effects 1/8-1/4 throttle so there is a bit of overlap with the slide and pilot circuits and thats about it.
2. so, i needed a leaner needle, ie a needle where the taper starts further down- unfortunately all the mikuni needles are ~2.5-2.6mm wide, wheas the ones in this carb are 2.75mm wide- a step in the wrong direction. when suzuki states about leaner needles in the manual, the needles in this series dont change much at all.
i was thinking what could i do, just to drop the needle 1 more clip position- i thought about drilling a hole inside the slide with a flat mill bit, just a bit deeper so that the needle sat a bit further down, i talked myself out of it, but then the next day i got 2 emails from marcus and james dean suggesting that mod, so i went for it. (had to file off 1mm from the end of the needle too).
i took it to the track yesterday and it seems to have done the trick, i actually raised the needle about 0.5mm with a washer and i am happy with the result. one note- this is a dangerous mod, i took the time to make sure the needle sits properly and has a little bit of "float" and i also had to use a tight fitting nylon washer ontop of the needle to take up the room.
i still need to pay a bit more attention to the main now, ive been eering on the side of caution with the main after the problems i was having with detonation with the old head/port timing specs- when i lost momentum in the higher gears going up hills full of deep soil it needed a bit of clutch to get back on the pipe.
Nephron- i though about calling bills, but i dont have the heart to since i am running an FMF pipe!:p its motoworld down near me in el cajon that are running the bills rm125- ironic since they dont sell suzuki's! ECC are running the Varner/FMF engines i think- my FMF pipe came of one of the ECC bikes, but i think this "rev" pipe had only one ride on it for a reason!
you are correct about the 39.5mm carb being a step in the wrong direction- everything i am hearing is that the 36mm carb is better, if i got a 36mm pwk it would be an easy starting point since i could use the older rm jetting starting point- i dont think needle selction is trivial for these swaps.
thanks again everyone :thumb: