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Main Jet Needle Question

  • Thread starter Thread starter Colorado CJ
  • Start date Start date
C

Colorado CJ

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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.
 
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.
 
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
 
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.

SU0086_012.gif
 
NICK! said:
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.

SU0086_012.gif
Click to expand...

mmmmmmm... yummy. im totally doing this tomorrow.
 
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.
 
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?
 
Colorado CJ said:
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?
Click to expand...

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.
 
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.
 
Nessism said:
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.
Click to expand...

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!
 
Colorado CJ said:
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!
Click to expand...

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.
 
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).
 
The cable might be bound or the carb clamps might be binding the throttle linkage.
Or a bad vacuum leak.
 
chef1366 said:
The cable might be bound or the carb clamps might be binding the throttle linkage.
Or a bad vacuum leak.
Click to expand...

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)
 
One thing that I did see that wasn't exactly right with the carbs is that the emulsion tubes (#40 in the previous drawing) were a little ate away where the main jet screws into them. The main jets still screwed in tightly, so I didn't think they would be a problem.

Could this be the problem with lean running? I wouldn't think that they would since the main jets seat against a washer when they are screwed in.
 
Colorado CJ said:
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)
Click to expand...

I would agree with the gross statement. Definitively rule out the possibilities though. Instead of stating you can't see a vacuum leak I would suggest after a short ride and it's idling @1800 rpm place a fan in front of the motor. Next spray WD-40 on all the places were it might be sucking additional air. If the idle drops . . . :).

PS: You stated it won't idle any lower than 1800 rpm. Is this true even after the initial 3-4 minute warm up?
 
Will do. The idle doesn't drop after it warms up. The idle does go lower once it is under load, i.e. I can putt around in first gear at about 1000 r.p.m. without it dieing.

I'll check again for vacuum leaks, but I don't think there are any.
 
I changed the needles over (did the washer swap) and the bike seems to be running much smoother and has alot more power now. I drove it a short distance and checked out the plugs. The engine doesn't seem to be running rich at all, the plugs look just about right.

I'll do a longer ride today and look at the plugs again to be sure (if it stops raining).

This really didn't solve the idling problem, although I can now turn down the idle to around 1500. I have a new slide coming for #3 carb (the slide out of #3 is much longer than the rest of the carbs, so the needle sits much lower). I think this will solve the idle problem as I think #3 is still running lean, making for a faster idle. I rechecked all boots and none have any vacuum leaks that I can see. All boots are in good shape and are very tight to the carbs.

I think the washer swap on the needles is the thing to do here at higher elevations (~5000 ft. and above) makes the engine run much nicer/smoother!
 
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