Flat spot from hell after jetting

mainlinecoffee · 02-19-2014, 06:13 PM

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.

blaine · 02-19-2014, 07:06 PM

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

mainlinecoffee · 02-19-2014, 08:39 PM

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.

blaine · 02-19-2014, 09:00 PM

Quote:

Originally Posted by mainlinecoffee

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.

mainlinecoffee · 02-20-2014, 01:02 PM

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

mainlinecoffee · 02-20-2014, 05:29 PM

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.

blaine · 02-20-2014, 07:11 PM

Quote:

Originally Posted by mainlinecoffee

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!!!

Water Warrior 2 · 02-20-2014, 08:45 PM

**jonathan180iq** · 02-25-2014, 12:52 PM

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)

mainlinecoffee · 02-25-2014, 07:19 PM

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

02-19-2014, 06:13 PM	#1
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	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. Login or Register to Remove Ads
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02-19-2014, 07:06 PM	#2
blaine Senior Member Join Date: Feb 2010 Location: P.E.I. Canada Posts: 3,784	Did you shim your needle.Sounds like it's lean in the Mid-range. __________________ If at first you do succeed, try not to look surprised.
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02-19-2014, 08:39 PM	#3
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	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. Login or Register to Remove Ads
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02-20-2014, 01:02 PM	#5
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	Well I guess I'm yanking the carb today thanks for the tip Login or Register to Remove Ads
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02-20-2014, 05:29 PM	#6
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	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.
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02-20-2014, 08:45 PM	#8
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409
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02-25-2014, 12:52 PM	#9
jonathan180iq Super Moderator Join Date: Jan 2007 Location: Dalton, GA Posts: 3,996	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)
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02-25-2014, 07:19 PM	#10
mainlinecoffee Senior Member Join Date: Oct 2013 Location: lexington ky Posts: 223	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
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