VM Carb Slide Shim position

[Suzuki_Don]

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).

 

[Guest]

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.

 

[Guest]

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..

 

[Guest]

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?

 

[Guest]

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.

 

[Guest]

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

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.

 

[KEITH KRAUSE]

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.

Sorry I couldn't get back sooner. Very busy. In fact, I'm out the door right now for work but wanted to check in.
I'll try to get back tonight if you can still use the help.
I try to align the two parts by using grease. The stuff similar to what many factories apply to their new bike chains. Looks like a thicker version of the typical white lithium grease I buy. Bearing grease can work too. Kind of difficult to explain how to hold the parts to avoid bungling things. I'll get back tonight as I'm late.

 

[Suzuki_Don]

Thanks Keith. Looking forward to your expert advice.
Cheers. Don.

 

[KEITH KRAUSE]

OK. Sorry to take so long. I should be in bed right now though.:roll:
I've worked with the parts you have but it's been awhile. Not all VM's use a ring (actual name for the thicker nylon spacer) with an indentation hole that lines up with the dimple on the brass plate. I don't know why they later changed the ring so it had no indentation hole but they always retained the dimpled plate as it was at first.
Yours is designed to fit together. If they don't line up, the dimple will not make a new indentation because the nylon is too hard and there's not nearly enough spring pressure to make a new indentation. If these parts don't line up/fit together, the jet needle will cock to one side even more so. I'm no expert as some think but I don't see any obvious problem due to the needle cocking more than normal. Yes, it could accelerate wear on the needle but I believe it would take a long time to show any significant effect from richness due to the extra rubbing. Also, the needle position would be just a tad leaner because the two parts didn't mesh and the needle wouldn't be allowed to go up completely under spring tension. But the difference would be fairly small and I don't think it would be that significant.
As for how to put them together and forget about any problems...
It's been awhile as I said working with these specific parts and it's hard to decribe how I use my hands to assemble these parts. Grease can help too or something similar. There are two ways as I remember. I'm fairly sure that I've fitted the parts correctly in the past but of course it's possible that one little mistake can happen and the parts didn't really align.
Grease isn't absolutely necessary as I've tried assembly both greased and dry. It's up to your finger dexterity. If you grease or use something similar, coat only the bottom of the ring so it sticks to the e-clip somewhat. Then apply just a couple of very small dabs to the bottom of the brass plate. Not so much that it makes part alignment difficult, just a bit to help the plate stick and be less likely to rotate.
I insert the needle assembly (greased-ring/e-clip/spacer/needle/spring) into the slide and pull down from under the slide until the top of the ring is flush with the seating surface for the bottom of the throttle arm/brass plate. Holding the needle with my index finger and thumb, the slide just sits still under that spring tension. Rotating the needle assembly if needed, the rings indent sits at 12:00 I believe is easiest.
Now you can take the brass plate and lower it into the slide. Align the dimple with 12:00 or whatever the ring hole is at. Dropping it in with your fingers isn't the best so use some small needle nose pliers and use the holes in the plate to lower it easy. Once down, gently position and press the plate down. If you didn't move things, the parts should be in alignment. Now you can carefully lower the throttle arm with the screws already installed. If you have the touch as I've aquired, you can manipulate the arm so it balances straight up. Take the screwdriver out of your mouth and start the screws. I have the screwdriver in my mouth because I don't have 3 hands and it just works for me.
If you were careful to not rotate or move the parts, they should be aligned and you're good.
A slight change from the above procedure is to stick the plate to the throttle arm first and lower it all down but it's up to you.
I've tried other things like holding the slide as described above and fully tightening the throttle arm screws. Then slowly rotating the needle trying to feel the ring hole "click" into the dimple but this often doesn't work because the ring doesn't always fully rotate with the needle. It can just stick in one spot and not move. If the ring does rotate easily, it's very simple to do it that way, but it usually doesn't work well.
Hope this helps. Kind of difficult to describe but I tried.

 

[Suzuki_Don]

Thanks. Great explanation Keith. you understand exactly where I'm at with this process. Two more questions. The manual says I have an Air Jet #1.4, where is this jet and how do I get it out? Also where is the Needle Jet on my bike? I have removed the jet holder that has the #80 Main Jet screwed into it and there is no # on the jet holder (this part has a number of cross drilled holes in it). Is the Needle Jet pressed into the venturi, if so how do you get it out. In the parts book it shows the jet holder with the main jet at one end and the needle jet at the other. Can you help me on finding both these jets and how to remove them. Thanks.
Cheers... Don

 

[Suzuki_Don]

Hi Guys can anyone tell me where these two jets are located? In previous post.