VM Carb Slide Shim position

[Guest]

On my GS550B there is a round shim that is positioned above the slide in the carb and holds the slide needle in position. This part is the same diameter as the slide and has four holes in it. One in the centre then one each at 9, 12 & 3 o'clock. There is a dimple or "tit" adjacent to the centre hole. Is the tit supposed to face up or down as on my carbs there are some each way. I believe it is important for them to go in the correct way. Any help out there. Maybe Keith or Nessism (or anyone else familiar with the non-CV carbs).

[greg78gs750]

this is a good question as i am putting mine back together today....guys?

[Nessism]

I can't remember exactly but seem to think that the nib on the plate matches up with a dimple on the slide or slide arm. All I can suggest is to look closely at the parts and try to match them up. Sorry can't be more specific. If necessary I'll pull one out of my carbs and tell you what I see.

[greg78gs750]

ok, i THINK that the nipple must go down....it is the only way (on mine) that the whole thing goes together "flat" ie without any funny bumps or anything.....anyone confirm this? there doesnt seem to be a corresponding dimple for it to fit into..

[greg78gs750]

ok, so, i looked at it again. when it is down, (the nipple) it "kicks" the needle a bit, at an angle. when it is up, the needle is straight. this, i suppose is obvious. wo which is right?

[greg78gs750]

ok, i guess we are on our own...im going **** down!

[Suzuki_Don]

Thanks Nessism and Greg. I think I can answer my own question now. The "tit" does go down and it fits into a corresponding hollow in the white thick upper spacer that goes on the slide needle above the clip (in my case in the centre groove). Don't ask me how to line the two of these up on reassembly though. And this would be why the needle kicks sideways on reassembly as the "tit" makes a new depression in the plastic spacer in a different position.

[KEITH KRAUSE]

Yes, dimple down. This is important as it forces the jet needle to go to one side under spring tension. If the needle just stayed straight and under no spring tension, the needle would rattle/vibrate and soon destroy itself.

[Suzuki_Don]

Yes, dimple down. This is important as it forces the jet needle to go to one side under spring tension. If the needle just stayed straight and under no spring tension, the needle would rattle/vibrate and soon destroy itself.

Thanks Keith. I worked out which way it went, but it's always better to have an explanation as to why it needs to be installed that way. Thanks heaps. Does the dimple need to fit in the original depression or will it just make a new depression in the top spacer as the two small screws are fastened to hold the bell crank linkage to the slide.
Cheers.

[greg78gs750]

thanks keith!! i knew there had to be a good reason.

[KEITH KRAUSE]

Does the dimple need to fit in the original depression or will it just make a new depression in the top spacer as the two small screws are fastened to hold the bell crank linkage to the slide.
Cheers.

I'd have to see your parts to answer that. Mikuni made many changes in the jet needle/slide area from '76 to '78. If the top spacer you mention is made of nylon, that's pretty hard stuff and I'd have to guess you would re-align the dimple into the original depression as you call it vs thinking the dimple will make a new indentation.

[KEITH KRAUSE]

Also, you mention it would be difficult to re-align the dimple into the original depression. Working with similar parts, I've found it easier to re-assemble these small parts by using a small dab of bearing grease here and there, to keep separate parts together as a unit. Wish I could see the assembly you're talking about. I might be able to offer a re-assembly tip that could help.

[Suzuki_Don]

Also, you mention it would be difficult to re-align the dimple into the original depression. Working with similar parts, I've found it easier to re-assemble these small parts by using a small dab of bearing grease here and there, to keep separate parts together as a unit. Wish I could see the assembly you're talking about. I might be able to offer a re-assembly tip that could help.

Keith you're the VM GURU. I've learnt so much from reading your threads. This forum is so fortunate to have knowledgeable people like yourself to impart knowledge and train up the lesser mortals like myself. I know there are many that would agree with me and be in your debt for the great help you have given each of us. I will try and post some pics tonight. I noticed also that there are differences in the 750 and 550 carbs, the 750 has one long bleeder pilot jet and the 550 has two of these, one on top and one way down in the bowels of the carb.

[Suzuki_Don]

Some Pics

Keith a picture of needle and spacers, also spring. The order from the top is thick spacer with dimple in it, needle clip, thin nylon spacer and then spring. Thick spacer is nylon as well.

[Suzuki_Don]

Pic of top thick spacer with dimple in it. The brass (I think) shim plate with the three holes in it has a corresponding dimple that sits in the depression in the thick nylon spacer. All this is way down inside the throttle slide. Very hard to line up.