Main Jet Needle Question

[Guest]

When I took apart my carbs to clean them, I noticed that the Main Jet needles weren't adjustable (they only had one place for the e-clip to go). Did Suzuki only start making adjustable Main needles after 1980, or do I have some kind of aftermarket needles?

I wanted to richen my fuel since my plugs look whitish when I pulled them today. So I either need to get adjustable needles, or a larger main jet.

Thanks.

[Nessism]

I don't think any US spec GS has adjustable needles. You can still adjust them though. Replace the plastic spacer on top the needle clip with a stack of thin washers. The shorter the washer stack, the higher the needle height (richer) because the spring pushes upward on the needle.

Good luck.

[Steve]

Actually, it was in 1980 that the carbs lost the adjustable needles.

.

[80GS750]

hmmm

i had adjustable needles on both my 1980 gs750 and my 78 gs1000

at least i think the 750 had adjustable needles... i know the 78 does

[NICK!]

You should have (if I remember correctly) a thick plastic washer above the e-clip and a thin plastic washer below the e-clip. See pic below, I believe 7 and 36 should be the washers. Reverse the washers, put the thin one on top and the thick one below and it will raise your needle. This was standard practice before jet kits were available. Hope this helps.

[catbed]

You should have (if I remember correctly) a thick plastic washer above the e-clip and a thin plastic washer below the e-clip. See pic below, I believe 7 and 36 should be the washers. Reverse the washers, put the thin one on top and the thick one below and it will raise your needle. This was standard practice before jet kits were available. Hope this helps.

mmmmmmm... yummy. im totally doing this tomorrow.

[NICK!]

We always did this when installing a header or a header/K&N filters. This along with drilling the pilot jets (we couldn't even get pilot jets in different sizes then) and of course larger main jets which were easily obtained. Once a good combination was found you'd write it down for future use, in the flat rate game every minute counts and knowing what to do right off the bat made for nice paychecks.

When Dyno Jet jet kits made the scene we about jumped for joy. The following Factory brand jet kits seemed to be even better after they were available.

I would hope that this washer "shuffle" won't be too much of a change should you have a stock intake and exhaust. If you bike is stock I'd stick close to home or ride with a plug wench and an extra set of plugs onboard until your satisfied the change was a good one.

[Colorado CJ]

Thanks Nick, I'll try that out! I'm pretty sure that it is running too lean as the plugs are white on the bar. The GS also idles too fast and can't be turned down lower that 1500-1800 r.p.m.s. The high idle speed would indicate a lean condition as well wouldn't it?

[Nessism]

Thanks Nick, I'll try that out! I'm pretty sure that it is running too lean as the plugs are white on the bar. The GS also idles too fast and can't be turned down lower that 1500-1800 r.p.m.s. The high idle speed would indicate a lean condition as well wouldn't it?

Yes, high idle could be lean. Did you adjust the pilot screws? They have more effect on the idle mixture than the needles; 550's like 3 - 3.5 turns out. Air leaks are also very common unless you changed the intake boot o-rings.

[chef1366]

That's going to raise the needle quite a bit. My guess will be too much.
With the stock plastic washer on the needle notice how much needle sticks out the top. Get some washers from Radio Shack and stack them to the exact same spot at the end of the needle over the clip. Removing one washer is equal to 1/2 notch.

[Colorado CJ]

Yes, high idle could be lean. Did you adjust the pilot screws? They have more effect on the idle mixture than the needles; 550's like 3 - 3.5 turns out. Air leaks are also very common unless you changed the intake boot o-rings.

I changed the boot and o-rings yesturday. I also read one of your posts on the pilot screw and set each one to 3.5 turns out, then synchronized the carbs. It is still idling too fast and I can't really fine tune the pilot screws until I can get the idle down. So, I think it is too lean.

Basically, I can adjust the idle screw down no lower than ~1800 r.p.m.s, any lower than that and the motor r.p.m.s die and the motor stops.

I'll give the plastic washer flip a try and see if that does the trick. Hope it works!

[Nessism]

I changed the boot and o-rings yesturday. I also read one of your posts on the pilot screw and set each one to 3.5 turns out, then synchronized the carbs. It is still idling too fast and I can't really fine tune the pilot screws until I can get the idle down. So, I think it is too lean.

Basically, I can adjust the idle screw down no lower than ~1800 r.p.m.s, any lower than that and the motor r.p.m.s die and the motor stops.

I'll give the plastic washer flip a try and see if that does the trick. Hope it works!

Waste of time to mess with the needles. Something else is wrong.

Did you check the compression? A bike that won't idle slower than 1800 rpm has something basic wrong.

[Colorado CJ]

No, I haven't checked the compression yet, but the P.O. said that it had good compression .

Other than the high idle and white plugs, the bike is running great. I took it out today and it seemed like it has plenty of power. It didn't stutter or act up at all in the 30 miles I drove it today (back roads, hills, stop/start driving).

[chef1366]

The cable might be bound or the carb clamps might be binding the throttle linkage.
Or a bad vacuum leak.

[Colorado CJ]

The cable might be bound or the carb clamps might be binding the throttle linkage.
Or a bad vacuum leak.

I can't see a vacuum leak anywhere (just replaced all the boots and o-rings with brand new OEM parts). The throttle also returns very strongly when I let go of it and I made sure the throttle linkage was not hitting the boot clamps (saw that one when reinstalling the carbs)