Flat spot from hell after jetting
 

Hey everybody. I got a 01 gz with stock carb six six sizes up on pilot jet and 140 main but I noticed that at any speed if under load if I snap throttle open it just flatlined and looses all power. If I baby it open it has power for days. I thought it would improve in warmer weather but no such luck...is it possible it is junked up from running fuel through a new gas tank? Someone said oil would build up in carb.

Did you shim your needle.Sounds like it's lean in the Mid-range. ;) :)

I got a shim kit but never installed,it was a part of a complete kit from sigma6 it didn't say it was needed. Guess I will throw it in tomorrow.

Yep I believe that is your problem.There is one shim in there that can be used to raise the needle & that may be enough. ;) :)

Well I guess I'm yanking the carb today thanks for the tip

Well I shimmed it with the shim that was on top and a extra one under it,it's like a whole new bike! Roars through all five gears without a stumble.

Great!!! Good to know problem fixed!!! ;) :)

:clap::clap::clap::clap:

For anyone coming into this thread later:

Pilot jet = idle - 1/3 throttle
Needle = 1/3 throttle to 2/3 throttle
Main jet = 2/3 throttle - full throttle (also affects other ranges)

And to top that off,jets come in two sizes,flow amount and physical dementions. Exhaust mods from header bac most likely get a pass but anything airbox will warrant a rejet