Needle shim modification

xt477 · 05-31-2007, 09:53 PM

I spent part of today talking to "THE" GZ mechanics. They run a state motorcycle safety class with almost 500 rebels and GZ's. I was telling him about my want to perform the shim procedure and he tells me that the best way to accomplish this is to drill the cap off of the pilot jet crank it closed lightly and then open it by 2.5 turns. Factory is usually around 1.5. He says that shimming will dump too much gas potentially causing exhaust back firing.

Will be a year before I find out but thought someone else might use this info.

Dupo · 06-01-2007, 12:14 AM

Well, sounds plausible. I went 2.5 turns out on mine after i put the aftermarket muffler on it. Before doing it, i would count the turns IN till it closed and make sure that its approx 1.5 turns factory setting. 1 full turn is alot ... i'd be checking plugs constantly to make sure its not running too rich.

Cant hurt to try though!

Easy Rider · 06-01-2007, 10:06 AM

Quote:

Originally Posted by Dupo

Well, sounds plausible. I went 2.5 turns out on mine after i put the aftermarket muffler on it. Before doing it, i would count the turns IN till it closed and make sure that its approx 1.5 turns factory setting. 1 full turn is alot ... i'd be checking plugs constantly to make sure its not running too rich.

Cant hurt to try though!

I'm determined not to do any radical mods. (ordered the 16T sprocket) but this sounds like it might be benefitial (and reversible) and I just hate those plugs in general.

Anybody else done this adjustment on a bone stock bike? Any obvious benefit?

I've got no complaints now but running just a tiny bit richer might help it pull with the taller gear ????? :??:

Gadzooks Mike · 06-01-2007, 10:12 AM

I have made two changes to my stock 2006 GZ - The needle shim mod and the 16T mod. If I had to do it over again, I would have done them both the day I got the bike home from the dealer.

majorgz · 10-10-2010, 12:01 AM

so just changing the air fuel mixture screw is the same as shimming the carb ????

blaine · 10-10-2010, 12:28 AM

Quote:

Originally Posted by majorgz

so just changing the air fuel mixture screw is the same as shimming the carb ????

The air fuel mixture is a single adjustment done with the bike running.Shimming the needle jet is a lot more involved and requires removing & dissembling the carburetor.This is explained extensively in "HOW TO'S".This can be difficult if you are not familiar with carbs.

:rawk: :2tup:

Easy Rider · 10-10-2010, 11:07 AM

Quote:

Originally Posted by majorgz

so just changing the air fuel mixture screw is the same as shimming the carb ????

NO.
The mixture screw mostly affects speeds at idle or near to idle with small throttle openings.
The shim affects mostly mid-range throttle positions.
The main jet is for higher RPMs at wide throttle positions.

(Blaine: Perfect!!) :biggrin:

majorgz · 10-10-2010, 11:29 PM

ok thanks i will keep that in mind thank you

majorgz · 10-12-2010, 08:58 PM

just got my pipe on and i dont need to do anything just slipped it on and a little welding. sounds bad ass really happy. now all them bad drivers can hear me coming.

Easy Rider · 10-12-2010, 09:25 PM

Quote:

Originally Posted by majorgz

now all them bad drivers can hear me coming.

Don't count on it.
All that extra noise is projected BACKWARDS from the bike.....and won't get any extra attention where you need it the most.

05-31-2007, 09:53 PM	#1
xt477 Member Join Date: May 2007 Location: Columbus Ohio Posts: 41	Needle shim modification I spent part of today talking to "THE" GZ mechanics. They run a state motorcycle safety class with almost 500 rebels and GZ's. I was telling him about my want to perform the shim procedure and he tells me that the best way to accomplish this is to drill the cap off of the pilot jet crank it closed lightly and then open it by 2.5 turns. Factory is usually around 1.5. He says that shimming will dump too much gas potentially causing exhaust back firing. Will be a year before I find out but thought someone else might use this info. Login or Register to Remove Ads
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06-01-2007, 12:14 AM	#2
Dupo Senior Member Join Date: Aug 2006 Location: Allentown, Pa Posts: 1,255	Well, sounds plausible. I went 2.5 turns out on mine after i put the aftermarket muffler on it. Before doing it, i would count the turns IN till it closed and make sure that its approx 1.5 turns factory setting. 1 full turn is alot ... i'd be checking plugs constantly to make sure its not running too rich. Cant hurt to try though! __________________ Photography Gallery *updated url - new site! Motorcycle Blog Facebook
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10-10-2010, 12:01 AM	#5
majorgz Junior Member Join Date: Oct 2010 Location: murrieta Posts: 7	Re: Needle shim modification so just changing the air fuel mixture screw is the same as shimming the carb ???? Login or Register to Remove Ads
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10-10-2010, 11:29 PM	#8
majorgz Junior Member Join Date: Oct 2010 Location: murrieta Posts: 7	Re: Needle shim modification ok thanks i will keep that in mind thank you
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10-12-2010, 08:58 PM	#9
majorgz Junior Member Join Date: Oct 2010 Location: murrieta Posts: 7	Re: Needle shim modification just got my pipe on and i dont need to do anything just slipped it on and a little welding. sounds bad ass really happy. now all them bad drivers can hear me coming.
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06-01-2007, 10:12 AM	#4
Gadzooks Mike Senior Member Join Date: Jan 2007 Location: Opelika, AL Posts: 162	I have made two changes to my stock 2006 GZ - The needle shim mod and the 16T mod. If I had to do it over again, I would have done them both the day I got the bike home from the dealer.
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