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Air Screw/Idle Adjustment

  • Thread starter Thread starter rcklobster
  • Start date Start date
R

rcklobster

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I just got my 82 GS 650 up and running and it runs fine as long as I give it some gas.

I cannot seem to get the bike to idle. The carbs were just rebuilt and haven't been retuned. I have tried to adjust the idle using the adjustment screw and as low as I can get it is roughly 2k revs. Could the air screws being out of adjustment cause this?

Any help would be greatly appreciated!
 
rcklobster said:
I just got my 82 GS 650 up and running and it runs fine as long as I give it some gas.

I cannot seem to get the bike to idle. The carbs were just rebuilt and haven't been retuned. I have tried to adjust the idle using the adjustment screw and as low as I can get it is roughly 2k revs. Could the air screws being out of adjustment cause this?

Any help would be greatly appreciated!
Click to expand...
If they are way off, maybe. Start them at 3 full turns out to start with and go from there. It should idle fine at that setting. Could it also be that your pilot jets are still not cleaned out enough yet?
 
If you had the carbs completely apart (including the rack), there is also the chance that your sync is off.

Ddaniels is correct, though, start by adjusting your IDLE MIXTURE ADJUSTMENT SCREWS (they are not "air" screws) to three full turns out from lightly seated. This will richen the mixture probably a bit more than necessary, but will only act like a "choke" and enable cold starting so you can fine-tune them.

To fine-tune the mixture screws, warm up the engine, then slowly turn each mixture screw in until you hear the engine speed drop a bit. Back the screw out about 1/8 turn, go to the next carb. When you have done all the carbs, come back, do it again, just to make sure.

When you are happy with the results, record your settings for future reference.

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I recently rebuilt the carbs for my 81 GS550L, and even after making the initial bench settings, you still need some test equipment to adjust them properly. One or more of your carbs are leading the way and since you are above the primary idle circuit, no adjustment of the airmix needles will help even out the air being pulled through the carb venturis. The adjustment for this would be the carb linkages after the airmix screws are set. As mentioned, 3 turns out on the mixture screw is a perfect starting place. I ended up at 3.5. Plenty of tech stuff on this sight is available to help you out. Borrow it or make a homeade carbsync nanometer. Rember, You'll never get it perfect.... but close enough is OK here.
 
+1 on the possiblity of the sync being out of...err...sync. Made a huge difference on mine after sync'ing the carbs. You will need adapters to sync them up. They screw into the little ports on the sides of the intake boots that screw into the head that are now occupied by screws.
 
Kurtgun11 said:
... and since you are above the primary idle circuit, no adjustment of the airmix needles will help even out the air being pulled through the carb venturis. ...
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Not sure just how to tell you this, but the "airmix needles" are NOT for synchronizing the carbs.
noway.gif


And, there are no "airmix needles" on this bike, they are "idle mixture adjustment screws".
They are there to adjust the MIXTURE, not the synchronization.



Kurtgun11 said:
... Borrow it or make a homeade carbsync nanometer.
Click to expand...
Save yourself some time, money and aggravation. Buy one.



Kurtgun11 said:
Rember, You'll never get it perfect.... but close enough is OK here.
Click to expand...
No reason WHY you can't get it "perfect".
shrug2.gif


It all depends on just how well you want your bike to run. :o

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I know this is an old thread, but hopefully I can help save someone the hours of research I did to find the answer. The on-line schematics, as well as parts suppliers, make no reference to the mix screws. My. GS300l had set for 18 years, purrs like a kitten right now. The adjusters are on top of the carburetors next to the head. I had to drill mine out to access them . I have attached(hopefully) an image I had found . Different bike than mine, but should clear things up.
 

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If you had to drill out the covers, it's obvious that your carbs have not been cleaned (properly) since they were assembled in Japan, 30+ years ago. Yes, that is where most of the mixture screws are. Some are pointing to the sides, rather than up, but are in the same general location.

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As I stated, my bike was setting for 18 years. I should have stated that the bike set for 18 years before I bought it at a yard sale for $100.00. I'm a newbie to motorcycle mechanics . I had spent hours looking for info on my GS300l , and from what I can tell on the Internet, I am not alone.
One site I went to thru a search was a thread on a pay site here the "expert" said that the mix screws didn't exist and the air was controlled thrum the jets.
I had a Honda back in Highschool, over 35 years ago. So all I was doing was showing other newbies who stumble on these "barn finds" where the air mixes are on a GS. Having spent the time researching and finding nothing, I hope it helps other newbies.
 
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