Air/Fuel screw?

[Anonymous]

where is this thing located on the VM carbs? I have a 78 GS550E

[earlfor]

Re: Air/Fuel screw?

VM carbs have two screws, a fuel pilot screw and an air screw.
The fuel pilot screw is underneath the carb and protrudes from the forward end on the underside of the carb (underneath the float bowl on the outside)
The air screw is centered on the left side of the carb body on carbs 1 and 2 and on the right side of the carb body on carbs 3 and 4.

Before making any changes, you should lightly turn each one all the way in, counting turns, so you will know what the original settings were. All carbs will most likely not be set the same due to slightly different flow characteristics on each cylinder. BY LIGHTLY, I mean to not turn them with any more force than you could exert holding the shaft of a jewelers screwdriver between two fingers greased with teflon. The point of the jet needle will break off EASILY.

Earl

where is this thing located on the VM carbs? I have a 78 GS550E

[Anonymous]

ok, well im not quite sure where to start. when i bought this bike, it ran ok, but I have come to realize that certain "mads" had be done to the bike. I have realized that the a/f screws havebeen seated completely on all the carbs. so the questions I have is how many turns out should I do? I have 102.5 mains, 25 pilots, needle is at position #4. how many turns out should I do on the a/f screws?

[Anonymous]

btt

[Detman101]

I'm wondering the same thing...

Dm of mD

[Anonymous]

nobody has any info on this???

[KEITH KRAUSE]

nobody has any info on this???

Why #25 pilots? Did you have #15 stock? Do you have pod's? Pipe?
Always adjust the side air-screws for the highest idle. Warm up the bike and adjust the screws 2 at a time in 1/2 turn increments and listen for the rpm's. After all 4 are set, re-set the idle to 1100 rpm with the idle screwknob. They generally end up 1 3/4 to 2 turns out.
Adjust the pilot screws underneath to 1 1/2 turns out for starters. They come from the factory set at different points because of differences in cylinders. You may have to fine tune for each cylinder by reading the plugs, but 1 1/2 will get you started. Don't ever seat these pilot screws tightly.

[Anonymous]

Yes I have both pods and a Mac 4-1 exhaust.

[KEITH KRAUSE]

You should'nt need #25 pilot jets. Too rich. Maybe because the pilot screws were closed off it ran. 17.5 pilots would work fine with the adjustments to the pilot screws.
If you still have the two floatbowl vent lines on, REMOVE them. This will allow better fuel flow.

[Anonymous]

ok, well i went to the bike shop earlier, got #17.5 pilots, and #90 mains. Im gonna start off with all a/f screws 2 turns out. with the needles at the 4th notch. once I start the bike and begin tuning the carbs, how do I adjust the air jets on the bottom of the carb??

[KEITH KRAUSE]

Just so there are no mistakes, let's get the names of the parts correct.
The pilot screws are underneath and in front of the floatbowls. These screws are for increasing or decreasing the amount of fuel in the mixture. Turning these out (counter-clockwise) richens the mixture. Turning them in (C-W) leans the mixture. With the 17.5 pilot jets, I would set the pilot screws at 1 1/2 turns out.
The air screws are on the side of the carbs. These screws are for increasing or decreasing the amount of air in the mixture. Turning them out (C-CW) increases the amount of air in the mixture and turning them in (C-W) decreases the amount of air in the mixture. Set these for the highest rpm possible as I said before.