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Main Area => General GS500 Discussion => Topic started by: TheDrunknmonky on January 06, 2009, 07:11:09 PM

Title: Lunchbox, jets and exhaust upgrade
Post by: TheDrunknmonky on January 06, 2009, 07:11:09 PM
I think this should be an easy one, but I want the experts opinions anyway..  If I change any one of these things, do the other 2 need to be done also?  What will happen, for instance, if I upgrade to a lunchbox and don't re-jet, or if i re-jet, but don't change intake, etc?  Based on what I'm finding, I'm thinking that these things have to be done together and that doing one by itself would hinder performance more than help it.  Input appreciated.  Thanks peeps!
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: dgyver on January 06, 2009, 08:10:08 PM
A rejet is needed when increasing the air flow, otherwise a lean condition will occur. Changing jets is simple and cheap.
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: TheDrunknmonky on January 06, 2009, 11:55:55 PM
I agree that a re-jet and intake are inexpensive upgrades and those are the 2 I'm planning on doing first.  My concern is not upgrading the exhaust at the same time.  Am I  going to create too much back pressure, or maybe not enough exhaust flow?  Is it possible to drill out the muffler, as opposed to replacing it?
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: galahs on January 06, 2009, 11:58:17 PM
You'll be fine if you keep using the stock exhaust.  :thumb:
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: gsJack on January 07, 2009, 05:51:54 AM
As I recall the earlier 89-00 pre 3 circuit carbs were jetted much leaner here in the US than they were around the rest of the world.  Common practice was to change US EPA jetted bikes to same size jets as used abroad.
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: Mandres on January 07, 2009, 08:13:18 AM
The way I understood it was that people have had a hard time finding a jet combo that works well with the lunchbox filter and the stock exhaust.  I'm sure with some patience and trial & error it could be made to work fine though.
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: The Buddha on January 07, 2009, 09:51:47 AM
You can do pipe without leaning it off too much. Lunch box is huge, that will make it very lean.
Pipe you can slide for a while if you put washers or have a little high float set (common on 89-00 as they wear high - them little buggers need fiddling every bloody year).
Cool.
Buddha.
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: mach1 on January 07, 2009, 01:53:23 PM
Doing an intake and jets are not that hard  even with stock exhaust hell even a slipon can rhe header restrick the f%$k out of the sxhaust. Doing a slipon only will be fine I did it and seen no change. Doin a rejet only is great. Doing the intake alone bad idead. Leaving the bike stock and ride and have fun really easy.
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: simoniz on January 07, 2009, 04:17:14 PM
Quote from: galahs on January 06, 2009, 11:58:17 PM
You'll be fine if you keep using the stock exhaust.  :thumb:

+1 on that, that is what I am running on mine.
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: ke7syv on January 08, 2009, 01:18:02 AM
Yeah true you can run a stock exhaust but you'll need to up the jets AGAIN after you change the muffler. Right?
Title: Re: Lunchbox, jets and exhaust upgrade
Post by: dgyver on January 08, 2009, 05:57:51 AM
Quote from: ke7syv on January 08, 2009, 01:18:02 AM
Yeah true you can run a stock exhaust but you'll need to up the jets AGAIN after you change the muffler. Right?


Correct. Jets are only $5-10 pair.