VM 26 bleeder question

[jknappsax]

I had cleaned and rebuilt the VM26s for my 1979 GS 1000, and carb #4 was way rich. I pulled the rack, took #4 apart, found a buggered O-ring, replaced it, and remounted the rack. This question is hard to describe, as I can't focus close enough on the part I'm about to describe. While I had #4 apart, I pulled the bleeder jet, and while it's open and clean, it looks a little beat-up. The PO had told me he had put a DJ Stage 3 kit in when he went to pods and headers. When I first pulled the carbs, I realized he had BOUGHT one, but never installed it. He had a little plastic box with the DJ parts in it, and I installed the DJ 138 mains, adjusted the needles, but the only bleeders are labeled 15, which it currently has in it. The new bleeders looked completely different, much shorter, and a bulbous end below the bleeder holes. They were not made to fit the VMs. He had a lot of info printed out about rejetting CV carbs, which is probably why he never got close to getting it right. I'm just wondering; what are these parts, and what are they for? All the other parts were right for some VMs, but maybe not the VM 26.

 

[Guest]

I think the bleeder jet you're describing is the pilot jet. Does it go next to the main jet with an o-ring at the top?

 

[Big T]

Post some pics so people will know what you are referring to

 

[TheCafeKid]

You have a DJ CV carb stage three kit.. Those mains are way too big for your VM carbs, tho they will swap, but the bleeders (pilots) are NOT the same.. Sell it and buy the right kit for your bike..

 

[jknappsax]

Pictures

Pictures

T, like I said, I can't focus close enough, even in macro, to show a pic. Here is a pic of the bottom of the carb with the float bowl, float, and needle valve removed.

Chef, in the attached pic, it's the one next to the main jet. I believe this called a bleeder jet, or an idle jet, or pilot jet. It's for the idle/low speed circuit.

Kid, the mains I'm using are DJ 138s; it also came with DJ 142s. I think the PO started with trying to rejet without a kit, then when he realized they were VMs, not CVs, he bought the DJ kit, but never installed it. I'll do more tuning tomorrow, because the main problem was the o-ring jammed in the fuel screw on carb #4, causing it to run really rich, as it never came close to 1 to 1 1/4 turns from bottomed. The kit had the right grooved needles, though there were a set of (I believe 5DL36 needles) with the grooves that I think were original during some point in the production run. I'm not doubting you, but it seems kind-of close with the original pilots and the 138s, and the different taper on the DJ needles. Do all you folks think I need to go for the new DJ kit? I just want this thing on the road! It doesn't have to be PERFECT for now, just rideable. With having to do the stator and r/r last year, I didn't really have a bike on the road, and it's killing me!

 

[jknappsax]

Kid, I think you're right!

Kid, I think you're right!

I've been trying to find instructions for the Dynojet Stage 3 kit #3304, which is the proper DJ kit for the VM 26, but they don't have a PDF of this kit. I cannot for the life of me find the instructions for the original kit the PO bought. Does anyone have an instructions for this kit? When I read the instructions for kit #3103, it lists DJ114 and 118 main jets for the stage1 kit, and DJ 165 and 170 for the Stage 3 kit. Considering that I have DJ 138 and 142 mains, I'm not sure WHAT kit this one is. And I just missed a sale on DJ kits!

 

[Guest]

It sounds like you have the right kit. The Dynojet jets are labled different than the Mikuni Jets. You want the 138's installed. The pilot should be a #15, which is stock for the 1000. Put the needle e clip in the 4th position from the top. Be SURE you re-install the two jet needle plastic spacers in the correct order. Thicker one goes above the e-clip and any spacer used, thinner below the e-clip.

Remove the two vent lines and leave the ports open. For starters set your side air screws at 1 3/4 and your pilot screws at 1 1/2. Once warmed up set the side screws at highest RPM, and you will probably have to fine tune the pilot screws, too. Vacuum synch and then check all your circuits by doing plug chops.

 

[jknappsax]

Thanks for the info, Bruce. 138s in, check. Pilots #15, check, but they are probably Mikuni #15s, vent tubes have bee removed, needles are in I believe in #4 from top (there was some mixed info about whether to use 3rd or 4th position, plastic spacers are above the e-clips, and I haven't shimmed them with washers to get the "1/2" position. I think I have the fuel screws at about 1 to 1.25 turns out, which may be why it won't properly idle without the choke, and the air screws at about 1 1/4, give or take for the max idle speed method. Carbs were synced after valves set properly, bench synced, then vacuum synced. When I have ridden it, it pulls hard from midrange, so it looks like the main jets are about right, and except for #4 being rich and black (kind of like a pro athlete!) because I used the wrong o-ring, the other plugs looked slightly lean. It ran well enough to do an accidental wheelie when I rolled on the throttle coming off a light in 1st gear. Do you think the #15 Mikuni pilots are ok to use with the rest of the DJ kit, or should I get DJ #15 pilots? I'm going out to continue the adjustment now, I'll let you know how it goes. Thanks again.

 

[Guest]

Dynojet says to use the stock Mikuni pilot jet. 4th grove from the top is always a good starting point...better to be too rich than too lean. If it's too rich you can use the small washers and go down by 1/2 steps. If you do end up changing the needle position, you will need to re-synch each time. Sounds like you are close! Do those plug chops at 1/8, 1/2, and full throttle position and read the plugs. That will tell you where you're at.

 

[jknappsax]

colortunes

colortunes

I'm using 4 colortunes to check the mixture, I've got them all looking right, but on carb#4, the fuel screw is only about 1/3 turn out; all the others are about 1 1/2 out, plus or minus a 1/4. I had carb #4 apart and took a good look at everything; the only thing was the chewed-up o-ring. I checked the float height for about the 50th time, and it is set at 25mm, just like the other three. It starts well, idles well after warmup, mixture looks good when the throttle is above about 1/2 way up. I had vacuum synced after putting on the carbs following setting the valves. The general consensus was that they wouldn't need resyncing after adjustment, even after changing the needle heights. Do you think I should resync the carbs? But the difference in carb#4 worries me. I'm thinking about taking her out for a ride to see how streetable she is. Do you have any ideas about carb#4? Do you think it's ok to go out for a local ride? Nothing looks lean, or acts like it. Once I'm satisfied that it's ok to ride without melting a piston, I'll start to do plug chops.

 

[jknappsax]

I just took her out for a ride, and something is way off. She starts ok with the choke, idles ok with the choke off, pulls strong from 2k on up to as fast as I can go on local roads (about 75 mph), but after coming to a stop after a couple miles, the idle is about 2k to 2500 rpm, and I can't bring it down. I checked that the pull and return cables are opening and closing completely, she has new boots, o-rings, K&N pods, a Two Brothers 4-into-1 header, a can that I took apart and repacked. I guess it's time to try another vacuum sync. Any other ideas?

 

[Guest]

Check for vacuum leaks at the synch screws, the vacuum port for the petcock, clamps from the boots to the carbs, etc.

 

[Guest]

Also, no matter what anyone else says, you need to re-synch the carbs after a valve adjustment OR if you move the jet needles.

 

[jknappsax]

These are all good suggestions, and I will start working through this stuff in the next days. First on my list is to check for any leaks, and then a vacuum sync. It felt good to take her out on the road.

 

[49er]

Remove #4 and any other fuel screw and do a visual comparison. You may find that a PO has replace the #4 screw with a replacement that has a thinner taper than the others. This would require the setting to be closer to the seat for the same fuel flow.

If the fuel screws are identical, you may have a damaged seat as a result of a screw tip being broken off by a PO.

 

[jknappsax]

Thanks for the suggestion. It gives me another avenue to pursue.

 

[jknappsax]

Hey,49er, I had achance to think about the fuel screws

Hey,49er, I had achance to think about the fuel screws

The fuel screws on the bottom of VM carbs does not come to a sharp, fine point like the air screws. The fuel screws are tapered somewhat, but the thinnest part is about 1/3 the thickness of the widest part. The ones people are warned about breaking are the air screws, on the side of the carbs. I've had these carbs apart to do a complete cleaning, and the fuel screws are identical. Unless somebody REALLY cranked down on them, I can't imagine that the seat would be damaged, and that is a part of the carb body, not a seat that can be changed. The fuel screws are pretty much set and forget. And none of the fuel screws had any damage to them.

 

[Guest]

The fuel screws ( by the float bowl) should come to a point and the air screws (on side of carb) has a blunt end.
If the fuel screw isn't sharp the tip may be broken off in the carb. Can you blast carb cleaner into the throat without the fuel screw installed?

 

[49er]

I agree with Chef. It's the fuel screws that are prone to getting broken off when they're screwed too tightly against their seats. They should have fine pointed tapers. If yours don't, you have got the wrong fuel screws fitted to the carbs.

I just checked my spare set and it's not possible to have the fuel and air screws mixed up, as the thread sizes are different.

 

[Guest]

The fuel screws ( by the float bowl) should come to a point and the air screws (on side of carb) has a blunt end.
If the fuel screw isn't sharp the tip may be broken off in the carb. Can you blast carb cleaner into the throat without the fuel screw installed?

This is correct. Here are some pics:

This is what the fuel screw underneath should look like:

And this is the side air screw:

If your fuel screws don't come to a sharp point, they are most likely broken off inside the small port that they screw into, as already stated. That would also explain not having any changes to performance after adjustment.