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I've thought about the needle adjustment a few times today. Just hard to guess without seeing the plugs myself and riding the bike. I hate to suggest the wrong thing and you decide to try it and it puts you through extra work. But it does sound like your problem is beyond the pilot circuit, so I wouldn't suggest a larger pilot jet or further pilot fuel screw adjustments.
I guess I'll have to trust your synch tool. If all other work was done the same though, it's hard to know what plug colors to base your jetting decisions on because you have uneven reads. If all other work was done the same, then it figures uneven vacuum is causing the uneven reads?? That's why I questioned the vacuum synch.
Back to the needles...Part of me thinks that a half position richer would be enough for a pipe only mod, and may well be, but I have to go with the old rule of choosing the richer choice if you think you're in the middle.
If you decide that too, at least you don't need any jetting spacers.
As chef said, you can get them at Radio Shack or most hardware stores.
chef has it mixed up a little about the placement of any jetting spacers. On the VM carbs, the spacers/washers never go under the e-clip. That placement wouldn't change anything. The spacers always go directly on top of the e-clip. Yes, the e-clip is placed lower (down) the needle to raise the needle/richen the mixture. Also, the thicker plastic factory spacer (ring) always goes back above the e-clip and the thinner plastic spacer under the e-clip. So if you did use a jetting spacer, the order would be from top to bottom: thicker plastic factory ring, jetting spacer, e-clip, thinner factory plastic spacer. Further, your factory e-clip position is the 3rd position (middle) from the top. If you decided to richen it 1/2 position (3 1/2), then you would place the e-clip in the 4th position from the top with the jetting spacer placed directly on top the e-clip. If you decide on one full position richer, then place the e-clip in the 4th position with no jetting spacer.
I suppose in this case, if I had/could find any spacers I wanted, I'd try a thickness somewhere between the .022" and full position of approx' .045". Something like .032"?? But it could be hard to find them at that precise thickness. Just dreaming.
Since you haven't removed the throttle shaft before to remove the slides and get to the needles, please ask and we'll try to help. Do you have a manual that helps? I know I've typed specific info on this subject but you'd have to do a search. I once explained it as detailed as possible, but that was quite a while ago, I believe to member "AOD's" tech thread. I also made a detailed reply about the bench synch and the fully closed and fully open slide positions. That synch info is part of Mark Hoomgar's tech thread "GS1K, bad gas mileage, attn Keith Krause"...or something like that, if you're interested.
Like I said, any disturbance/change of the needles on your carbs requires a new bench/vacuum synch.
You shouldn't have any problems with this job if you pay attention to part order and use good fitting tools. The stopper bolt that holds the throttle shaft can be a bit stiff. Use a good fitting tool, as always. Another area that gives some people trouble is the two smaller Phillips screws that are down inside the slide area and connect the throttle arm to the slide. They can be stiff/stuck sometimes, so use a GOOD/CORRECT fitting tool, not just the best you have at home. Push down solidly and then turn. If the heads on these get stripped, you're in trouble. I don't hear of too many here having problems with them, but wanted to warn you.
Also, be sure to replace the thin, dimpled brass plate under the throttle arm in the same position as you found it. Don't replace it upside down. Also pay attention to the three OPEN holes you'll see in the slide/plate/throttle arm. They must all line up. Make sure everything goes back as it was is what I'm trying to say.
After you're ready to re-install the needle asembly, plate, throttle arm, screws, it may take a little fumbling to get everything lined up. I take a very small dab of grease and apply it to the thin brass plate. I then "stick" the plate to the throttle arm and feed the two screws in. While carefully pulling (thumb and index finger) the jet needle and its spring down so that it's fairly flush with the slide (don't let the spacers pop off), I lower the plate/throttle arm/screw assembly as a unit and line up the screws with their holes. Holding everything level, I "stand up" the throttle arm so it balances straight. With my screwdriver ready, I then carefully thread in the screws. Snug them both then tighten them firmly, but don't over-tighten and damage the heads. You may have to get back in there again, hopefully not.
For some, it takes a little practice, or three hands, but I hope this helps you.
The throttle arm to throttle shaft bolts should be torqued to about 4 ft/lb.
Just wanted to bring up those possible trouble points.
Good luck and ask if you have a question.
I guess I'll have to trust your synch tool. If all other work was done the same though, it's hard to know what plug colors to base your jetting decisions on because you have uneven reads. If all other work was done the same, then it figures uneven vacuum is causing the uneven reads?? That's why I questioned the vacuum synch.
Back to the needles...Part of me thinks that a half position richer would be enough for a pipe only mod, and may well be, but I have to go with the old rule of choosing the richer choice if you think you're in the middle.
If you decide that too, at least you don't need any jetting spacers.
As chef said, you can get them at Radio Shack or most hardware stores.
chef has it mixed up a little about the placement of any jetting spacers. On the VM carbs, the spacers/washers never go under the e-clip. That placement wouldn't change anything. The spacers always go directly on top of the e-clip. Yes, the e-clip is placed lower (down) the needle to raise the needle/richen the mixture. Also, the thicker plastic factory spacer (ring) always goes back above the e-clip and the thinner plastic spacer under the e-clip. So if you did use a jetting spacer, the order would be from top to bottom: thicker plastic factory ring, jetting spacer, e-clip, thinner factory plastic spacer. Further, your factory e-clip position is the 3rd position (middle) from the top. If you decided to richen it 1/2 position (3 1/2), then you would place the e-clip in the 4th position from the top with the jetting spacer placed directly on top the e-clip. If you decide on one full position richer, then place the e-clip in the 4th position with no jetting spacer.
I suppose in this case, if I had/could find any spacers I wanted, I'd try a thickness somewhere between the .022" and full position of approx' .045". Something like .032"?? But it could be hard to find them at that precise thickness. Just dreaming.
Since you haven't removed the throttle shaft before to remove the slides and get to the needles, please ask and we'll try to help. Do you have a manual that helps? I know I've typed specific info on this subject but you'd have to do a search. I once explained it as detailed as possible, but that was quite a while ago, I believe to member "AOD's" tech thread. I also made a detailed reply about the bench synch and the fully closed and fully open slide positions. That synch info is part of Mark Hoomgar's tech thread "GS1K, bad gas mileage, attn Keith Krause"...or something like that, if you're interested.
Like I said, any disturbance/change of the needles on your carbs requires a new bench/vacuum synch.
You shouldn't have any problems with this job if you pay attention to part order and use good fitting tools. The stopper bolt that holds the throttle shaft can be a bit stiff. Use a good fitting tool, as always. Another area that gives some people trouble is the two smaller Phillips screws that are down inside the slide area and connect the throttle arm to the slide. They can be stiff/stuck sometimes, so use a GOOD/CORRECT fitting tool, not just the best you have at home. Push down solidly and then turn. If the heads on these get stripped, you're in trouble. I don't hear of too many here having problems with them, but wanted to warn you.
Also, be sure to replace the thin, dimpled brass plate under the throttle arm in the same position as you found it. Don't replace it upside down. Also pay attention to the three OPEN holes you'll see in the slide/plate/throttle arm. They must all line up. Make sure everything goes back as it was is what I'm trying to say.
After you're ready to re-install the needle asembly, plate, throttle arm, screws, it may take a little fumbling to get everything lined up. I take a very small dab of grease and apply it to the thin brass plate. I then "stick" the plate to the throttle arm and feed the two screws in. While carefully pulling (thumb and index finger) the jet needle and its spring down so that it's fairly flush with the slide (don't let the spacers pop off), I lower the plate/throttle arm/screw assembly as a unit and line up the screws with their holes. Holding everything level, I "stand up" the throttle arm so it balances straight. With my screwdriver ready, I then carefully thread in the screws. Snug them both then tighten them firmly, but don't over-tighten and damage the heads. You may have to get back in there again, hopefully not.
For some, it takes a little practice, or three hands, but I hope this helps you.
The throttle arm to throttle shaft bolts should be torqued to about 4 ft/lb.
Just wanted to bring up those possible trouble points.
Good luck and ask if you have a question.
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