83 gs750es jetting problems

[patricks]

Hello
I recently just got my 1983 gs750es up and running. I put and aftermarket full vance and hines exhaust system on it. It starts and runs great until it hits the 3,000-4000 rpm range then it bogs viciously. After the 4,000 range it seems to run well. I am unsure of what size intermediate and main jets it should have in it. I live in Montana at about 3500 feet in elevation. I would sure appreciate it if anyone out there could give me some input on the jetting.

thanks
patrick

[Nicholaschase29]

try driving it where you get the most bog, try to keep it there for as long as you can (30 sec - 1 minute) the longer the better, then pull in the clutch and hit the kill switch simultaniously and coast to a stop. Get your spark plug wrench out and check the color of the plug. If it is whitish it is lean, and if it is black it is rich. Do this test to get started, and then you can see where you need to go from there...

[chef1366]

I would raise the main jet to 122.5 and raise the needle 2 notches or 4 washers if shimming.
This is just a start. To get it dialed in do throttle chops like explained in last post.

[derwood]

......also when you are trying to determine if it is rich or lean, try using the choke if it gets better with the choke its lean. Shut off the fuel to the carbs and go, if it gets better as the carbs near empty you're rich. have fun.....and put new plugs in to read

[rgierer]

I have a GS700 with pods and the 4 to 1 exhaust. A bike similar to yours. I bought a dyna stage three kit and move the e-clips up a notch and used the stage 1 main jets. I am saying all this to say. the needed intervention was not as much as I expected, and it didnt need to cost me as much as it did.

IMHO and I don't know much I would follow NC's advice. Sounds like you have a mid range isses (e-clip) and it can be adjusted with washers rather than a big expense. Lots if guys here have done it.

Conventional wisdom is for you to get your mains correct and then follow. If you follow that thinking you will also check out your mains as NC directed. It will typically run fine lean but it is hard on the engine. You can pick up 1 size larger main jet from Dennis Kirk for a quite reasonable price but only if you need it, you very well may not.