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subxero · April 28th, 2013, 12:31 PM

Hey all,

Yesterday i removed airbox, kleen air sys, then installed POD filter, emissions block off plate, nojima moto gp full exhaust, I shimmed needles and changed pilot and main jets.

So here is where i am at

3 washers under needle
Initially installed 115 Kelhin mains
#40 pilot
Did not touch floats,
Did not touch idle mixture screws...yet

With this set up i did a quick ride testing throttle at various positions ect...

At idle after a blip the rev needle returns to idle speed with no hang or drop. Seems good
1/4-3/4 throttle all seems smooth and responsive.
WOT i felt flat and lazy from 6k-11k with no hesitation but then came on strong after 11k to limit.

Then i would get a good bit of backfire when decel with no throttle after 3/4-WOT

Wasn't sure which way to go but seems like my main jet is primary issue
I had 118's and richer is safer so i put the 118's in today. Did a quick test ride. idle -3/4 throttle felt good still, maybe better,
WOT felt better 6k-9k but 9k-11.5k ish i get hesitation type symptom,
then 11.5k-limit it pulls really strong.

Still lots of backfire when decel no throttle. IF i put choke on full and decel there is no backfire.

The backfire on decel would seem to be a lean condition because the choke or throttle cures it right? All the circuits less the MAIN seem to be good on the way up the revs so why would one not be good on the way back down?

Is it more possible my MAIN is RICH, or LEAN and the backfire is a by product of the MAIN jet being off? and has nothing to do with other aspects of the carb tuning?

Out of tune main jet leaves excess unburnt full? or is to lean to ignite mixture and then it is ignited by next cycle further down the pipe?

I have 120 mains laying around somewhere, i need to find them. I have 1 112 main and would need to order one more before i could try them.

I also have BRT-TIS, i feel like i could probably play with the ignition timing a little and it might help with the hesitation i am getting with the 118 at 9k-11k

Thoughts?

April 28th, 2013, 12:31 PM	#1
subxero dirty boy Name: Joe Location: Johnstown, PA Join Date: Sep 2012 Motorcycle(s): I don't even know anymore?? Posts: A lot. MOTM - Apr '14	ideas for my jetting Hey all, Yesterday i removed airbox, kleen air sys, then installed POD filter, emissions block off plate, nojima moto gp full exhaust, I shimmed needles and changed pilot and main jets. So here is where i am at 3 washers under needle Initially installed 115 Kelhin mains #40 pilot Did not touch floats, Did not touch idle mixture screws...yet With this set up i did a quick ride testing throttle at various positions ect... At idle after a blip the rev needle returns to idle speed with no hang or drop. Seems good 1/4-3/4 throttle all seems smooth and responsive. WOT i felt flat and lazy from 6k-11k with no hesitation but then came on strong after 11k to limit. Then i would get a good bit of backfire when decel with no throttle after 3/4-WOT Wasn't sure which way to go but seems like my main jet is primary issue I had 118's and richer is safer so i put the 118's in today. Did a quick test ride. idle -3/4 throttle felt good still, maybe better, WOT felt better 6k-9k but 9k-11.5k ish i get hesitation type symptom, then 11.5k-limit it pulls really strong. Still lots of backfire when decel no throttle. IF i put choke on full and decel there is no backfire. The backfire on decel would seem to be a lean condition because the choke or throttle cures it right? All the circuits less the MAIN seem to be good on the way up the revs so why would one not be good on the way back down? Is it more possible my MAIN is RICH, or LEAN and the backfire is a by product of the MAIN jet being off? and has nothing to do with other aspects of the carb tuning? Out of tune main jet leaves excess unburnt full? or is to lean to ignite mixture and then it is ignited by next cycle further down the pipe? I have 120 mains laying around somewhere, i need to find them. I have 1 112 main and would need to order one more before i could try them. I also have BRT-TIS, i feel like i could probably play with the ignition timing a little and it might help with the hesitation i am getting with the 118 at 9k-11k Thoughts?