Un-adjustable VM22 Slide.

[Seth]

Hello, I am trying to bench sync my 1979 GS550E carbs. There are four Mikuni VM22s.
After following the instructions for VM Rebuilds I found on the forum, I mounted the carbs and took the bike for a ride. My bike kept dying when I released the throttle about 5 miles into the ride. I would have to hold it slightly open to keep the bike idling at stop signs or outright dying on the move. I also noticed that my Idle adjust screw changed position and doesn't contact the throttle rocker until it is fully screwed in now. After removing the carbs to sync again, I cannot get these boogers to all set at the same resting slide height. (I'm using a 1/16th drill bit for reference) While the number 2,3 & 4 carbs (naming from riders left) all adjust quite nicely from the locknut/screw assembly under the topcap, the number 1 carb will not raise at all. It sits on the bottom of the carb throat no matter what I do to the screw/locknut combo up top. If I tighten the screw, it raises all the other carbs at the same time, but the number one slide stays in the full closed position. If I loosen the screw the slide stays in the same spot. I pulled that slide, and It seems to be assembled correctly. Im stumped.

I'm sure these problems are related. I'm thinking if I could get that number one carb adjusting again, The throttle rocker will be able to adjust to the right spot.

Does anyone have any advice on getting that slide adjusting again?

Thanks, Seth

[OldVet66]

All the slides are lifted with a common shaft so the bolt on the bell crank of the number one slide is either missing or was never tightened.

[Seth]

All the bolts are there and tight. All slides lift at the same rate when you turn the throttle rocker. The #1 slide just won't adjust by itself.

[TxGSrider]

I don't know anything about the VM carb racks, but on the other carb racks Ive messed with there is usually one slide that is not adjustable and you use that for your reference then adjust the other three around that one (of course that one will be adjusted by using the idle speed screw).

[Big T]

Why offer advice when you lack knowledge?
All VM slides adjust

[Steve]

I don't know anything about the VM carb racks, but on the other carb racks Ive messed with there is usually one slide that is not adjustable and you use that for your reference then adjust the other three around that one (of course that one will be adjusted by using the idle speed screw).

That may be true about the other racks you have "messed with", but does NOT apply to his VM carbs.

Seth, you might have to break the rack apart again, so you can remove the adjuster mechanism from two carbs and compare them. Other than the fact that each carb is individually adjustable, I don't remember exactly how the adjuster works, which is why I suggest comparing two of them.

.

[Big T]

Hello, I am trying to bench sync my 1979 GS550E carbs. There are four Mikuni VM22s.
After following the instructions for VM Rebuilds I found on the forum, I mounted the carbs and took the bike for a ride. My bike kept dying when I released the throttle about 5 miles into the ride. I would have to hold it slightly open to keep the bike idling at stop signs or outright dying on the move. I also noticed that my Idle adjust screw changed position and doesn't contact the throttle rocker until it is fully screwed in now. After removing the carbs to sync again, I cannot get these boogers to all set at the same resting slide height. (I'm using a 1/16th drill bit for reference) While the number 2,3 & 4 carbs (naming from riders left) all adjust quite nicely from the locknut/screw assembly under the topcap, the number 1 carb will not raise at all. It sits on the bottom of the carb throat no matter what I do to the screw/locknut combo up top. If I tighten the screw, it raises all the other carbs at the same time, but the number one slide stays in the full closed position. If I loosen the screw the slide stays in the same spot. I pulled that slide, and It seems to be assembled correctly. Im stumped.

I'm sure these problems are related. I'm thinking if I could get that number one carb adjusting again, The throttle rocker will be able to adjust to the right spot.

Does anyone have any advice on getting that slide adjusting again?

Thanks, Seth

Let's clarify:

1. If you take the carb tops off and rotate the common throttle rod, the arm for #1 raises up along with 2, 3,4?
2. The arm is attached to the slide by the small screws at the bottom of the arm?

[OldVet66]

If you used the VM rebuild tutorial tutorial from BikeCliff's Web Site you might want to revisit #16 and #17 and see if that is correctly adjusted. The slides can affect each other but I have never seen it to the point where it would supersede the Sync adjustment for a slide. Also check them at full throttle and see if there is a glaring difference in the slides. Everything keys off slide #3.

[Seth]

All right guys, I think I fixed the issue.
I pulled out the slides themselves and noticed that slide 3 measured something around 80mm from top of the slide to the bottom of the needle, where the others measured about 74mm.
When I disassembled slide three, it exploded all over the workbench. I think I had the round plate with three holes in between the spring and the bottom washer, instead of the correct order being: spring,small washer, clip, large washer, plate, arm. This had also flattened my small washer to the point of needing to have the edges taken down on the wife's emory board to fit back in its hole. Now everything is nice and even when reassembled, and my throttle rocker butts directly up against the idle screw hole. It was very easy to bench sync this time around.

The take away, If you have a slide assembled incorrectly it will be a pain/impossible to get your carbs to sync.

Thank you all for the input!

[748cc]

Sorry to hi-jack this thread, but can anyone tell me what size the locknuts are on the sync screws? I'm assuming 10mm but not sure. Thanks in advance.

[hannibal]

I believe they are 10mm as well.

[748cc]

Confirmed today that they are in fact 8mm locknuts, NOT 10mm. Be sure to have that wrench on hand before tearing down your tank, etc.