High Altitude Jet Sizes on GS650

[Anonymous]

Hey all, I've got an 83 GS650 shaft drive, I think it's the only one in existance, and no one makes a jet kit for it, only the 81-82s. It's got an aftermarket air filter with most of the airbox still intact. I'm going to put a straight through exhaust on it for the sound, not really looking for a performance enhancment, and need to know what size main and pilot jets to put in, and whether or not the needles will have to be raised. I called Dynojet to see what they say for the 81-82 bikes, and it appears either these bikes use different jets or Dynojet does, because they told me 155 mains, I currently have 105s. Any suggestings or starting points would be appreciated.

[gspaul]

https://www.motorcyclecarbs.com/default_w43.cfm

https://www.4strokes.com/tech/howtojet.asp

See how you go!

[snowbeard]

try http://chopperbuilders.net they had a jet size by # of modifications chart I saw somewhere.

keep us up on how it goes, eh? I've considered a straight pipe for the 850 I'm working on...

what part of CO are you in?

edit: looked on there and didn't find it, but I know I read an article not too long ago that had some sort of formula like

pods = +1 jet size
4-1 pipes = +2 jet size
straight pipes = +1

etc etc.,
then add up all the mods and subtract 1...

certainly don't use this as I don't remember the numbers, but just so you'll recognize it. it may have been on the forum part??

[SqDancerLynn1]

Jets from Dyno are marked different.

http://www.thegsresources.com/_forum/viewtopic.php?t=17814