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Main Area => General GS500 Discussion => Topic started by: reajcox on March 30, 2011, 08:23:44 AM

Title: My 93 GS throttle issue.
Post by: reajcox on March 30, 2011, 08:23:44 AM
Seems as though I've got a dead spot in my throttle. I cleaned the carbs and it helped a lot. They weren't really dirty or varnished but the seals and orings were old and needed cleaned or replaced.

Anyway, at about mid throttle it just gets flat then all of the sudden it hits and takes off like a rocket again. I may be jetted wrong or something but I'm still with the same set up as last year. Vance & Hines exhaust, stock air box, and stock jets. Seems to get better after it warms up. I don't remember it being this bad last year maybe it was and I was just used to it. New year though and I'd kinda like to clean that up.

If you have any suggestions or advice let me know.

Thanx!
Title: Re: My 93 GS throttle issue.
Post by: 4strings on March 30, 2011, 09:37:35 AM
Just wondering what RPM range the dead spot happens at.
Title: Re: My 93 GS throttle issue.
Post by: 5thAve on March 30, 2011, 10:06:56 AM
Tell us what rpm and also what throttle movement pls. It's not uncommon for a carburetted bike to stumble briefly if the throttle is whacked open quickly .. momentary lean condition very possible. You have aftermarket exhaust and stock airbox. Have you changed the jetting to richen the mixture to suit your exhaust mod? If not then you are likely a little more lean than stock, which was already quite lean.

Anyone else want to chime in? I'm curious what is your jetting, and what is your throttle movement when you feelthe flat spot?
Title: Re: My 93 GS throttle issue.
Post by: reajcox on March 30, 2011, 04:58:34 PM
Its right about mid rpm say 3500 to 4000 and I'm still running the stock jets which are 37.5 and 122.5 if I remember right. Very seldom am I hard on the throttle I just kinda roll through it.
Title: Re: My 93 GS throttle issue.
Post by: reajcox on March 30, 2011, 05:02:17 PM
I may just go and put the K&N in it and do a total rejet. Any Idea where I would want to jet it to and what brand of jet. I think I may have a bad lean spot that's causing my issues. I gotta say though.

This is a great look at how stable of a bike this is... when it's wrong it still runs and rides great.
Title: Re: My 93 GS throttle issue.
Post by: 5thAve on March 31, 2011, 06:57:58 AM
Jets are not difficult to do and are definitely worth the time and a few $.  Go to the for-sale forum and check the stickies at the top of the list of threads. There is one by Buddha for pricing for jets. He will put together exactly the kit of jets you need. Just tell him whether you're running stock airbox or K&N, and tell him you have aftermarket exhaust. 

As for the flat spot, sounds like it could be just an unfortunate effect of having the aftermarket exhaust. Probably has changed the acoustics in the exhaust length. I presume it's a slip-on fitted to stock headers that have been cut somewhere behind the collector? There may not be much you can do about this. Try a different slip-on if you're really upset by it. Going to K&N may make another change that could either help or further hurt the flat spot. No way to know except to try it. Jets may help slightly but probably the biggest benefit will be easier starting and better off-idle throttle response (e.g. starting from a stop).

Best of luck. Let us know what you try and what are your results.  See also the Wiki for some guidance (http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting   and   http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting-LeanOrRich?)   :thumb:
Title: Re: My 93 GS throttle issue.
Post by: reajcox on March 31, 2011, 07:13:36 PM
no it's a Vance and Hines header and muffler kit.

I'm already on the Buddha for jets he recommended staying off the K&N.

Let you know the end result :cheers: