fuel problem ??

[fj11.5]

hi all, since finding out the po had drilled out the main jets, ive now installed a set of #115 ,s  , but noticed today, first ride since fitting them, ive gained a  amount of power back  everywhere in the rev range, buuuut reving up around 6/7 k when changing up and pulling the clutch in, backing off revs to change she surges foward like ive powered on not off , could i have the needles to high, 4 sllot from the top, standard here and uk is 3 , , uni pods, and 4into 1 exhaust , floats set at 22.000000001 ? mm or there abouts    , blip test is perfect drops straight back to 1000k no hesitation high or low

[andyb]

Changing the main jet will absolutely change the way the needle reacts.  Probably the best way to check is a plug chop from half throttle and 5krpm, but that requires a good safe place to test things.

If you're WOT, is there a big surge of power just past 6k?  If so, that just says that the needles are wrong (usually too low, but all bets are off when you find drilled mains!), and that you're getting closer to the right mixture once you're off the needle.  Is there a stutter when you run half throttle from 2k through 4k?  That could be the needles transitioning on into a rich state.

Experiment and see what works for you, needles are fortunately really easy to dink around with as you can leave the carbs on and it takes maybe ten minutes to tweak them.  A whole clip change should be a really dramatic difference, in either direction.  Drop them some and see what happens.

Blip testing should be grossly unaffected by the needle position unless they're way, way off and you're blipping hard enough to open the needle circuit.  With pods and a decent pipe, I'd wonder if you shouldn't go up a bit more on the mains and see how much more power is up there, a 120-125 could well pick up another few ponies!

[fj11.5]

thanks andyb, i tried 125,s , smaller hole than the drilled 112,s but felt really flat, much better with the 115,s , ill lower the needles back to 3rd spot and see how she is,, and your right a plug chop would explain a lot, , no stutter beween 2 and 4 k , didnt have any issues till i hit the highway and opened her up , getting close as she has never ran this good , never new the jets had been drilled till i seen a set of standard 112,s

[fj11.5]

ripped out the plugs, showing a nice light grey/ tan colour , gap was a little wide, have changed themto the standard plugs, as i had iridium ones , just eliminating causes,