Too Much Confusion... need definitive screw/jet adjustment numbers

[aedi006]

First the info: '82 GS850GL - Stock
I have tried hard to do my homework on this one... but different thread/people/days use different names for the screws and jets in carbs. Here I will be using the terminology and pictures (so there can be no doubt) from the carb rebuild series hosted here on GSResources. For each of the four screw/jets I have found in the carb rebuild I need the following info (I also realize that different people/bikes will have different answers to these questions, but more infor is better than my current confusion):

a. Should it be fully seated (i.e. tight so I can no longer turn)?
b. If not fully seated, how many turns off fully seated?
c. If the adjustment is not turn based how is it done (for example I think the process for adjusting part #1, air screw, is to turn it while idling until peak idle is found)?
d. What does the screw/jet control
e. What are the alternative names for the screw/jet
f. I have some slight backfire, will adjusting this screw/jet help (I am also checking for exhaust leaks)?

The naming convention is:

Part #1 - Air Screw - First Picture
Part #2 - Air Jet - Second Picture
Part #3 - Needle Jet (or Main Jet, both used in Rebuild series) - Third Picture
Part #4 - Pilot Jet - Fourth Picture


#1

#2

#3

#4

To help here is a form for the answers:

Part # XX
a. XX
b. XX
c. XX
d. XX
e. XX
f. XX

Thanks in advance.

 

[Guest]

 

[Nessism]

Only the Air Screw is adjustable. Set it to 1.75 turns from fully seated and then adjust slightly for best idle (should be within 3/4 turn). All other jets should be fully seated to make sure they don't vibrate loose.

 

[Steve]

OK, I'll take a stab at this.

Part # 1 - air screw
a. Should it be fully seated (i.e. tight so I can no longer turn)? NO.
b. If not fully seated, how many turns off fully seated? Start with about 1 1/2 to 2 turns out.
c. If the adjustment is not turn based how is it done? Adjust for peak idle after engine is at operating temperature. Adjust idle speed with main idle control as necessary.
d. What does the screw/jet control? It adjusts the mixture at idle and very low throttle settings.
e. What are the alternative names for the screw/jet? Idle mixture.
f. I have some slight backfire, will adjusting this screw/jet help (I am also checking for exhaust leaks)? If it is not out far enough, the mixture might be rich enough to cause a bit of backfiring.


Part # 2 - air jet
a. Should it be fully seated (i.e. tight so I can no longer turn)? Yes, install until snug.
b. If not fully seated, how many turns off fully seated? Fully-seated.
c. If the adjustment is not turn based how is it done? No adjustment.
d. What does the screw/jet control? Controls maximum amount of air possible to be adjusted with item #1. Also controls air that will be mixed with item #3.
e. What are the alternative names for the screw/jet? None that I know.
f. I have some slight backfire, will adjusting this screw/jet help (I am also checking for exhaust leaks)? Only adjustment is replacement with a different size. That should only be necessary if using individual pods or a header.

Part # 3 - needle jet
a. Should it be fully seated (i.e. tight so I can no longer turn)? Yes.
b. If not fully seated, how many turns off fully seated? Fully-seated.
c. If the adjustment is not turn based how is it done? No adjustment, other than replacement.
d. What does the screw/jet control? Controls the amount of fuel and air that will go past the needle for mid-range operation. By the way, the main jet screws in to the bottom of the needle jet. It is only about 3/8" long, the needle jet is about 2" or so, and sticks up into the carb throat.
e. What are the alternative names for the screw/jet? None, that I know.
f. I have some slight backfire, will adjusting this screw/jet help (I am also checking for exhaust leaks)? Maybe adjusting the needle height, but not this needle jet.

Part # 4 - pilot jet
a. Should it be fully seated (i.e. tight so I can no longer turn)? Yes.
b. If not fully seated, how many turns off fully seated? Fully-seated.
c. If the adjustment is not turn based how is it done? No adjustment.
d. What does the screw/jet control? The amount of fuel in the pilot circuit, which includes idle and just off-idle.
e. What are the alternative names for the screw/jet? None that I know.
f. I have some slight backfire, will adjusting this screw/jet help (I am also checking for exhaust leaks)? No adjustment.


Keith Krause is a better source on carb issues, he might shed more light on this for you. He might even correct me if I have made a mistake here.


.

 

[ggreenfield]

Ah this is exactly the thread I have been looking for. All the 'jet' photos in one place and labeled. Thanks! \\/

Can it be a sticky or linked to the carb series maybe? I know too many stickies isn't always a good idea either.

 

[Steve]

You can make your own "sticky".

Open a blank document in Word (or your other favorite word processor). Find the pictures you want to illustrate whatever procedure you are working on. Copy the picture, paste it in Word. Add whatever comments you want, go get your second picture, etc. If the pictures are bigger than necessary, you can re-size them by clicking (once) on the picture, then dragging one of the corners to change the size. When you are done, save it with a name that makes sense to you. You can also print it out and put it in a binder for handy reference. Then, if you ever get the pages dirty , you can re-print as necessary.

I have done this for my Wife's GS, my GoldWing and my son's Venture Royale.
The guy that bought my Voyager 1300 appreciated the volume of notes that came with it.


.

 

[ggreenfield]

You can make your own "sticky".

Open a blank document in Word (or your other favorite word processor). Find the pictures you want to illustrate whatever procedure you are working on. Copy the picture, paste it in Word. Add whatever comments you want, go get your second picture, etc. If the pictures are bigger than necessary, you can re-size them by clicking (once) on the picture, then dragging one of the corners to change the size. When you are done, save it with a name that makes sense to you. You can also print it out and put it in a binder for handy reference. Then, if you ever get the pages dirty , you can re-print as necessary.

I have done this for my Wife's GS, my GoldWing and my son's Venture Royale.
The guy that bought my Voyager 1300 appreciated the volume of notes that came with it.


.

Yes I do just that w/ cars, motorcycles, guitars and pc's. I was looking for something exactly like this for a few days when I happened across this thread entirely by accident.