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Carb Adjustment Help??

  • Thread starter Thread starter dyoung
  • Start date Start date
D

dyoung

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'83 GS 850G. I'm into my first carb on my first try at rebuilding carbs. I disassembled carb #1 and soaked and am now about to put them back together but i'm a little confused about what screws are seated and what screws are for adjusting fuel and air. In the float bowl you have the main jet and pilot jet, is it correct that the main jet is seated and the pilot is used to adjust the fuel intake? then is the pilot air jet that goes on the airbox side seated or used as adjustment because i'm not sure how to adjust the air intake? I know the mixture screw is 3 turns back but just wondering which screws to adjust and how much to generally adjust them to? also, it looks like i'll need a drain screw gasket and the tiny washer that goes with the mixture screw. does anyone know where to get these odd parts? THANKS!!
 
All jets are seated there is no internal adjustment done other than checking float height.
the pilot air jet that goes on the airbox side seated
Click to expand...
Yes it is seated too. The air mixture screws are adjusted as you mention and once the carbs are back on and the bike is running, there are 3 adjusters ( one between each two carbs) that are used for synchronizing them. You will, of course, need a vacuum synchronizer for this procedure. The last adjuster is the idle knob, the big one under the cam which the throttle cable is attached to. This is used for setting the final idle.

All of this information will be in the manual and if you don't have one there will be one on BassCliff's site.

So to recap seat all jets and only fiddle with air mixture screws, the synchronizing adjusters and the idle knob.

Good luck with it.
Spyug

PS. Be sure to install fresh o-rings and fresh orings for the intake boots ( to the head) failure to do that might cause you a lot of grief in getting the carbs to run right as you likely will have some airleaks. The orings in the carbs may look fine but if you pull them apart slightly , you may find they are cracked or split and will thus leak. Get them from Robert Barr at www.cycleorings.com Cheap insurance for good running carbs.
 
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thanks Spyug, that put my mind at ease. i do have fresh boots for carbs, airbox, the carb o ring kit, and intake orings but the carb o ring kit didn't come with replacement bowl drain gaskets. will an oring suffice?
 
Spyug was correct on all counts, let's just go into a little more detail.
dyoung said:
In the float bowl you have the main jet and pilot jet, is it correct that the main jet is seated and the pilot is used to adjust the fuel intake?
Click to expand...
One out of two there. Both of them are JETS and get snugged up firmly.


dyoung said:
then is the pilot air jet that goes on the airbox side seated or used as adjustment because i'm not sure how to adjust the air intake?
Click to expand...
Again, that is a JET and gets snugged up firmly.


dyoung said:
I know the mixture screw is 3 turns back but just wondering which screws to adjust and how much to generally adjust them to?
Click to expand...
The idle mixture adjustment screws can start 3 turns out from lightly seated, but that is only a starting point. After the bike is fully warmed up, you will adjust those for best idle, probably by turning them in. They may end up somewhere in the range of 2 to 2 1/2 turns out, but starting at 3 turns is a good start.

This is where your mixture screws are located.
IMG_2958.jpg


If you look on the throttle shaft between the carbs, you will see the sync adjustments.
They are a screw and locknut assembly and will require a gauge set to adjust them properly.
This picture should remove any doubt on what to adjust.
adjustmentscrews.jpg


dyoung said:
... also, it looks like i'll need a drain screw gasket and the tiny washer that goes with the mixture screw. does anyone know where to get these odd parts?
Click to expand...
Did you not get an o-ring kit for your carbs from cycleorings.com? Hopefully you did not waste your money on "carb rebuild kits", as they typically contain inferior parts. The jets in your carbs are probably perfectly fine, and you only need to dip the carbs and replace the o-rings. If you buy the carb (and intake) o-ring kit, the o-rings for the drain screws are only an additional penny. You can also get the washers for the mixture screws from cycleorings.


.
 
I know the feelin of pretty much knowing what you're doing but once you get it apart more questions pop up. Have you seen basscliffs site? The step by step is awesome on carb rebuilds, with pictures. Your bike will thank you and you'll be happily amazed when your bike starts up without drama for the first time as you get ready to vacuum synch the carbs. Again, look at basscliffs site for that step by step.
 
dyoung said:
thanks Spyug, that put my mind at ease. i do have fresh boots for carbs, airbox, the carb o ring kit, and intake orings but the carb o ring kit didn't come with replacement bowl drain gaskets. will an oring suffice?
Click to expand...

I used gasket material from my local auto part store to make bowl drain gaskets for mine. I was afraid to use the o-rings I bought with the set because that's not what I removed from the bowls. I took an old gasket and traced it on the gasket paper, cut the circle out, and punched it with a standard hole punch for the center circle. Worked great for my set of carbs.
 
Don't forget to do bench sync when you reassemble carb rack- before putting carbs on head.
 
Thanks Guys, that makes alot more sense now that the jets get seated and all the adjustments can be done from outside the carb. I will definately do the bench synch and eventually the carbtune when I end up getting one or find someone around here who has one. and unfortunately I forgot to add the fuel drain o ring to my order so i'll have to go out and find one that fits.
 
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