Please help with my new gs!

[Briggs]

Just bought a 89 from a kid who knew nothing about the bike. My problem is that it runs real rich and studders between 2900 and 3500 rpm. The bike has a full vnace and hines, external k&n filter, and what confuses me is that the jets sound kinda screwed up. The stock mains arm still in it, and I think it has a different needle, because it is shaped real wierd. How could it run rich with the 122 main. I am thinking of just ditching all the jets in the carbs and starting fresh with a jet kit. I am a little scared though because I don't want any lose of drivability. Dose anyone have a similar setup? Should i even bother with a kit i have read on some sits to just get some different mikuni jets and do some shimming. What is better. Remember I want this thing to pure in all ranges not not just above 4000. PLEASE HELP!
Mark

[Black Snowman]

The engine can drop below 4000? Huh, I had know idea

Seriously thought there is a good chance it either has a DynoJet/K&N jet kit or at least a needle from that kit in there if it doesn't have a straight taper.

The stock needle has only 2 contours and looks sort of like this

| |
.V

and the DynoJet/K&N has 3 contours and is more

| |
.V
.|

If it's only running rich at idle/very little throttle (which there is a good chance of) you might be able to just adjust the mixture screws. It's harder to tell if it's running rich at higher RPMs unless your check the plugs right after maintaining those RPM for a while.

If the slides are drilled and plugged near the needle then you definately have the DynoJet kit and I'd say just play with the mixture screws until you can't get it any better then think about rejetting.

[Briggs]

the slide has one hole with plug in it and the other is taped with nothing in it and it has the crazy needle that you drew. What do you recomend to do with that air screw in or out, like a half turn?

[Black Snowman]

In will lean it up, so try half a turn at a time in and test it. Might also want to make sure the carbs are synced.

[Briggs]

What about the slide? Is it modified too, it has a plug in one side and some threading in the other. Also I forgot to add that I tried moving the clip on the needle one step leaner. It did make my plugs leaner, but I seam to of lost some power at the high end. Does that seam right to you?

Mark

[ltsiopou]

Hi,

Probably it has the Dynojet kit if it has the holes plugged, the strange needle and the number of the main jet is 122. I think the mikuni numbers are like 120, 122.5, 125, 127.5, 130, etc. Just play with the screws and it 'll be ok. I had similar problems (rich on that setting) in the range you talk about (a lot of vibrations and some mild explotions) and after I played a bit with the screws now the bike runs great and it is smooth.