GStwin.com GS500 Message Forum

Main Area => General GS500 Discussion => Topic started by: ladybrid on March 01, 2004, 01:20:23 PM

Title: *another* jetting question
Post by: ladybrid on March 01, 2004, 01:20:23 PM
Ok, last fall did the re-jet and muffler (cobra) and it's all better, except that I have to leave it on "prime" to keep it from loosing power.  Now the bike came back out (still too "new" a rider to trust myself on nearly new tires in the rain), and I just want to make sure that I'm not missing anything.  Do other folks leave the fuel flow on "prime" after re-jet and muffler swap?
Title: *another* jetting question
Post by: Briggs on March 01, 2004, 01:36:46 PM
IMO the fact that you have to leave it n prime has nothing to do with you rejetting your bike. I rejetted last summer and it ran fine on the normal position. This weekend i pulled it out from the winter sit and now i have to run it on prime. There is something wrong with the petcock.
Title: jetting/petcock
Post by: ladybrid on March 01, 2004, 01:56:24 PM
My housemate (car mechanic) and I took the petcock off and checked it when we were trying to trouble shoot, and it appeared to be functional... at least air went through it on the different settings.   :dunno:  I guess I could track down a new one and try just replacing it.
Title: *another* jetting question
Post by: BadBatzMaru on March 01, 2004, 04:11:48 PM
shouldnt need to be on PRI.  if you have to keep it on prime then maybe its a vacuum problem?? I'm just learnin about all this stuff myself, but I just got my rejetting right (pipe and k&N) and no need for running on prime...   once last year I messed with my carbs and didn't reconnect the vacuum line correctly... that gave me loss of power with the petcock in ON and had to run on prime... so I'd guess check for vacuum leaks, kinked hoses that kind of thing... hope that helps at all..
Title: prime
Post by: ladybrid on March 01, 2004, 04:49:20 PM
I will have to check all the lines again.  I suppose there is always a chance that something was dirty or old.  But it does run!  Now to just get it off "prime" and onto "on".
thanks for the suggestions!
Title: *another* jetting question
Post by: GRU on March 01, 2004, 06:17:14 PM
either the vacuum or the frame petcock...if the vacuum works then take off the petcock take it apart...look for anything that doesn't look right
Title: *another* jetting question
Post by: aslam on March 01, 2004, 06:42:46 PM
I've heard about alot of problems with the fuel petcock, but luckily so far I haven't experience any of them on my own.

Is the general solution to replace the petcock or just run the reserve fuel line directly to the carbs?

ASLAM.
Title: *another* jetting question
Post by: GRU on March 01, 2004, 07:18:52 PM
it's much cheaper to run a straight lime from the petcock to the carbs but you should also put a fuel shut-off switch so you don't flud the carbs...
Title: *another* jetting question
Post by: scratch on March 02, 2004, 01:30:10 PM
No probs with the stock fuel selector so far here either.

I hope you can make one of our rides this year, Ladybird! I'm planning on three (June, July, August), one of 'em will be at one of Doc Wong's riding clinics (it's free!). For the other rides I think we'll have 'Fast' and 'Slow' groups this time (I'll be leading the 'slow' group and keeping us together as a group this time :) ).
Title: *another* jetting question
Post by: aslam on March 02, 2004, 04:26:30 PM
I prefer the fuel petcock myself.  It's a good feature to have the reserve.

ASLAM.
Title: ...
Post by: ladybrid on March 02, 2004, 06:09:02 PM
Yes, Scratch, I hope to get over my case of nerves and be comfortable enough to ride *with* people too... lol... I just tend to be overly careful about some things... but I'm still here, still learning

Ok, so potential stupid question... if some people are bypassing the petcock altogether, then could a *different* non-gs petcock that was more reliable be spliced in?  
-brid
Title: *another* jetting question
Post by: Kerry on March 02, 2004, 11:06:09 PM
For a couple of ideas, check out the pictures in the thread Fuel Starvation Issue? 1990 GS500 (http://www.gstwins.com/forum/viewtopic.php?t=4624)

Make sure you follow the link in the post just BEFORE the one with the pictures.  It will take you to thread with a diagram showing one way to hook up the single fuel line.  Keep reading until you see my post with the warning about the reversed fuel lines in the diagram.

For feedback from someone who has tried the simple lawnmower petcock, see the thread wanted: petcock (http://www.gstwins.com/forum/viewtopic.php?t=6679).

I'd sure like to hear from someone who's tried the $11 "Universal Shut-Off Valve".  It's the only one in those pictures with a built-in way to MOUNT it to the bodywork.
Title: petcock
Post by: ladybrid on March 03, 2004, 01:07:20 PM
Thanks Kerry!
I'm going to look for a stock petcock, or at least a replacement diaphram I think, so far the "universal" and straight shut offs all seem to suggest they are not good for engines over 250cc...
ah more online shopping!