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Main Area => General GS500 Discussion => Topic started by: JP86NYC on May 03, 2011, 08:43:44 PM

Title: New Member - Jet Size Question
Post by: JP86NYC on May 03, 2011, 08:43:44 PM
I just bought my first bike 2 weeks ago: a '92 GS500e. I want to get it running well before I take it to the streets in NYC.

The bike has a V&H exhaust and a performance K&N air filter. I confirmed that its running lean by looking at the plugs. I want to rejet the carbs to get it running more rich. I read on another post (by Buddha) to rejet a factory bike like this: 40 pilots, 125 mains, set mixture screw 3 turns out. What sizes would be good for a bike with a performance exhaust and air filter?

By the way, this forum is great. Tons of great info.
Title: Re: New Member - Jet Size Question
Post by: reload on May 04, 2011, 06:04:57 PM
http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting (http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting)

try out the wiki. alot of the routine info is covered in there.

im also in nyc. welcome!
Title: Re: New Member - Jet Size Question
Post by: JP86NYC on May 16, 2011, 01:49:48 PM
Thanks. Yeah I just finished the job this weekend just going from the wiki page. This site is a great resource. I messed up the hose routing, so it doesn't start, but I printed the diagram and I'll get it right next time I get a chance to mess around with it.

Where are the good places to ride near the city? I live in Astoria Queens.
Title: Re: New Member - Jet Size Question
Post by: The Buddha on May 16, 2011, 02:04:38 PM
Pipe and K&N is 150 mains - the rest is as you posted.
Cool.
Buddha.
Title: Re: New Member - Jet Size Question
Post by: reload on May 16, 2011, 03:04:39 PM
Quote from: JP86NYC on May 16, 2011, 01:49:48 PM
Thanks. Yeah I just finished the job this weekend just going from the wiki page. This site is a great resource. I messed up the hose routing, so it doesn't start, but I printed the diagram and I'll get it right next time I get a chance to mess around with it.

Where are the good places to ride near the city? I live in Astoria Queens.

if im bored by myself i do laps around the GCP/BQE/Belt/Van Wyck or throw in a mix of the LIE to make it a little shorter.  Just go off peak, otherwise you'll just be lane splitting for 20 miles lol.

if in groups we usually head out to the Long Island roads or up to Bear Mountain.
Title: Re: New Member - Jet Size Question
Post by: JP86NYC on May 31, 2011, 12:14:04 PM
Yeah I found the table with suggested jet sizes on the Wiki page. I put in 40 pilots and 150 mains, but its still starving for gas at higher RPM's. The jet needles are not stock, so I'm replacing them with stock ones with 2 washers on each. Hopefully that will help.

And yeah thanks for the advice. I haven't been on anything faster than 30 mph (city driving sucks), but I'll take a ride down the GCP one of these days. I hear its a nice ride. I wanted to get comfortable on slower roads first, but I'm ready now.

Thanks for the info guys. I'm learning a lot from this site.
Title: Re: New Member - Jet Size Question
Post by: ben2go on May 31, 2011, 06:42:46 PM
I am running 40/142.5/1 washer/3 turns.I run a right side Hayabusa flow through muffler and a lunch box airfilter.I use this site to help tune my carbs.It gives a full description of how to jet properly and what effects what and at the rpm range it has an effect. http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html
Title: Re: New Member - Jet Size Question
Post by: plewis51 on May 31, 2011, 07:00:50 PM
Quote from: ben2go on May 31, 2011, 06:42:46 PM
I am running 40/142.5/1 washer/3 turns.I run a right side Hayabusa flow through muffler and a lunch box airfilter.I use this site to help tune my carbs.It gives a full description of how to jet properly and what effects what and at the rpm range it has an effect. http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

AWESOME LINK!  :woohoo:
Title: Re: New Member - Jet Size Question
Post by: The Buddha on May 31, 2011, 08:49:41 PM
Quote from: JP86NYC on May 31, 2011, 12:14:04 PM
Yeah I found the table with suggested jet sizes on the Wiki page. I put in 40 pilots and 150 mains, but its still starving for gas at higher RPM's. The jet needles are not stock, so I'm replacing them with stock ones with 2 washers on each. Hopefully that will help.

And yeah thanks for the advice. I haven't been on anything faster than 30 mph (city driving sucks), but I'll take a ride down the GCP one of these days. I hear its a nice ride. I wanted to get comfortable on slower roads first, but I'm ready now.

Thanks for the info guys. I'm learning a lot from this site.

Ok 40/150 and aftermarket needles and you're starving @ high revs ... OK 2-3 things I gotta ask.
1. Stock bike ? or have the heads been decked/ported/flowed ?
2. Petcock causing stavation ? Or floats set too low ? or somehting not letting in fuel ?
3. You sure you're not confusing rich for lean ?

OK start with the simplest and the free-est. Raise the floats and run it, improve or get worse ... Post back. After market needle anyway makes it richer especially up high.

Cool.
Buddha.
Title: Re: New Member - Jet Size Question
Post by: JP86NYC on June 01, 2011, 09:06:55 AM
Ok 40/150 and aftermarket needles and you're starving @ high revs ... OK 2-3 things I gotta ask.
1. Stock bike ? or have the heads been decked/ported/flowed ?
2. Petcock causing stavation ? Or floats set too low ? or somehting not letting in fuel ?
3. You sure you're not confusing rich for lean ?

OK start with the simplest and the free-est. Raise the floats and run it, improve or get worse ... Post back. After market needle anyway makes it richer especially up high.

Cool.
Buddha.
[/quote]

Buddha,
     1) I am the 3rd owner of the bike and I'm ASSUMING there has been no top-end work done to this bike, but I cannot be 100%.
     2) I haven't yet checked the float height. This could very well be the problem I know. I'd like to also check the petcock filter (?) to see if that's clogged or dirty. Would you suggest a petcock upgrade?
     3) The way that its "bogging" at high RPM seems like its rich, but the plugs are completely white, thats why I'm thinking its running lean.

As soon as I replace my COMPLETELY bald rear tire (should be done by tomorrow) I'll start riding it and playing with it. I'll post back. Thanks for the help.








Title: Re: New Member - Jet Size Question
Post by: ben2go on June 01, 2011, 09:35:26 AM
If you suspect the petcock,replace it with a 2004-07 Honda CRF250X.I have started a write up on this and I will finish it this weekend.
Title: Re: New Member - Jet Size Question
Post by: JP86NYC on June 01, 2011, 10:35:51 AM
Thanks Ben2go,
     I'm at work right now looking at petcocks on ebay haha. I'll try to find one of these and let you know how it goes. Thanks.
Title: Re: New Member - Jet Size Question
Post by: The Buddha on June 01, 2011, 11:21:10 AM
Plugs white @ what throttle position ?
Did you do a high rpm plug pull ?
You can be rich on jetting and lean due to fuel flow as well, but lets not go there just yet.
Cool.
Buddha.
Title: Re: New Member - Jet Size Question
Post by: JP86NYC on June 01, 2011, 01:21:57 PM
I haven't done a high RPM plug pull since I rejetted. I just ASSUMED it was still lean cuz they were white when I replaced them (after rejet). I guess I was just making an ASS out of U and ME. I'll do a high RPM pull.

Once I replace my rear tire, fix my air leak (found one between carb and intake manifold, and ordered replacement O-ring and collar), put it stock needles with 2 washers each, set proper float height, and replace petcock with '07 CRF250X petcock (can't hurt) I'll re-evaluate and let you guys know how its running. I would think I should be good at that point.

Thanks guys...