VM26SS Carbs

[mike1414]

I did in fact take the carbs off multiple times and as I was rebuilding them according to the tutorial the first time, repetitively shining a light into the slot, sticking a screwdriver in there to try and get them out, and trying to install the new ones that I bought I was never able to have any success in getting any out that may have been there or getting the new ones in. I know it never hurts to rebuild them again, but unfortunately my schedule allows me minimal free time. I'll see if some tinkering may lead me in the right direction

[allojohn]

What you've got looks like a set of VM's I have here which does not use the pilot fuel screws - at all. The holes are just left blank.
The VM26's on GS1000's sold here in NZ didn't have the pilot fuel screws either.

as for the pilot mixture screws they are there
turn the carbs upside down on the engine side of the carbs right in the center and deeply recessed in the hole is the pilot mix screw it may have a little metal cap covering it (most don't but you never know)

GregT says carbs without fuel pilot screws are real, at the very least in NZ.....

[mike1414]

Hey guys, so it's been a bit, but I finished up with finals and had the day off from work so I went out to tinker. I tried my best to measure the float heights (first try), but I honestly don't know how well it went because they all seem quite off. I believe that the float heights are supposed to be set somewhere around 21mm correct? or is it 24mm? I don't have the correct tool to measure, so I used a typical ruler with inches/centimeters. I took my measurements in inches (mostly down to the /32 mark) but converted them to metric. Just in looking at them, some of the float heights differed via inspection. I took the measurements with the carbs straight upwards as if they were on the bike. The measurements are as follows:

Carb #1: float at 1 3/16" (30.16mm); tang just before compressing the tip of the needle: 15/16" (23.8125mm)
Carb #2: float at 1 3/32" (27.78125mm); tang just before compressing the tip of the needle: 7/8" (22.225mm)
Carb #3: float at 1 3/32" (27.78125mm); tang just before compressing the tip of the needle: 7/8" (22.225mm)
Carb #4: float at 1 1/8" (28.575mm); tang just before compressing the tip of the needle: 1" (24.5mm) --> I adjusted the tang towards the needle because of the overflow issue, but it still overflows now just as much as before. It appears to me that the little 90 degree tab on the float clip seems to be turned outward more than the others though the float height itself is still around the same range as the others.

I don't honestly know if these could help, but here are just some random pictures of the floats. I figured maybe someone could identify something of which they are skeptical or something that looks inappropriate.










I went for about a 10 mile ride last night and noticed that there was slight leaking from the drain screw in carb #1, no apparent draining from the overflow or drain from carb #2, draining from carb #3 overflow drain, and draining from carb #4 overflow drain.


Just for kicks, I also further validated that there is no pilot screw. I scraped and cleaned and blew and tried my best to figure it out, but there really is no pilot screw. Alright, any thoughts?

[allojohn]

On regular VM266SS's the float height is 24mm, measured upside down (with the valve effectively closed) from the flat area inside the lip to the top of the float. Give me a bit - I'll post a photo....
Incorrect float heights makes a massive difference.

Edit: Post #3 has a perfect photo courtesy Rob (AZR)

[mike1414]

Ah, I see. I did not measure from inside the lip nor from upside down. I'll knock that out and be back with an update soon

Ok just got the measurements:

Carb 1: 25mm
Carb 2: 25mm
Carb 3: 24mm
Carb 4: 26mm

I left the float bowl gasket on, though, so these measurements do not take this into account. I figure add (+1) to each number for the true number, making it respectively 26, 26, 25, and 27. So they are clearly off, but would this make such the difference? If so, does anyone have a link to a tutorial on here as to how to measure? I haven't found a great one or anything of great help.

[hannibal]

I assume these are VM carbs. What really matters is the height of the fuel in the bowl. I used some clear line and taped it in the fuel drain bowl port. This will show you where your fuel level is when the bike is running. Disregard where the float tang is. If the bowl has too much fuel, lower the"fuel height". If you lower the float and the fuel height remains high, you have a problem with the float needle valve.

[mike1414]

Correct, VM26SS. I assume you mean to check the fuel level similar to this?

https://www.youtube.com/watch?v=0ogUMEpKERM (start at about 5 mins.)

[mike1414]

Well I got out there and gave it a shot, took the drain plug out and connected a piece of clear tube to the drain plug outlet and bent it upwards. Turned the pet cocky on prime and gas filled the clear tube only to about 1cm below the lip of the float bowl. That certainly doesn't seem like the bowl is filling too much. Did I do this incorrectly or was I on track for testing it correctly? Also noticed my petcock leaked a bit. Thoughts?

[mike1414]

I also realized today that my needles do not have rubber tips on them; the tips are simply just metal, but they are not scarred or marked or anything. You can see a clear line where they plug the hole in the seat. Would having no rubber be causing an issue?

[hannibal]

I had good height when the bike was off but the fuel level rose when it was running.

There's not supposed to be rubber on the float valve needles. If you can see or feel a line, you probably need to replace the needles.

[mike1414]

Well guys, I have been trying to tinker with my floats at a variety of different heights, 22mm-27mm, and have played with the height of the tang as well to adjust the height of the actual needle in its seat. It seems as though no matter my float height, it still spills just as much gas and I still have the bogging down/crap throttle response within the first 1/8th of a turn. It doesn't seem as though my needle is worn, but I was going to purchase a new one anyways. Would there be reason that perhaps the needle/seat are just too large? Does anyone know the factory size and whether or not getting a smaller needle/seat would make a difference? I checked the carb vent, and it is free of debris (I read somewhere that debris in the vent could cause issue). What do you all think?

[geol]

Both Kawasaki and Suzuki VM carbs used the idle adjust screw pointed down as on this set of carbs. Also, the pilot mixture screws purchased were never used on a Suzuki and the ones shown were used on Kawasaki VM26s 77/78 KZ1000 models. I coiuldn't tell for sure but did these carbs have air screws? Looked like someone tried drilling but didn't see an air screw and LAST... the pointy tip of a pilot mixture screw does fit up into a hole in engine side lower venturi in front of a hole that fuel flows from the pilot jet. The pilot mix screw is used to fine tune the pilot circuit in conjunction with the air screw/pilot jet on the Suzuki 26s. It might not be a bad idea to measure to see if these are actually 26s... they should measure about 26.5 - 26.7 mm or something like that on the venturi ID on the engine side.

[allojohn]

You may never get these carbs right Mike. As GregT pointed out early in the thread these carbs may be from a foreign GS1000. At this point I'd look for a set from a regular US '78-'79 GS750.

[hannibal]

The float valve needles and seats do come in different sizes. For some reason, I think the stock size is 1.5. If you look at them closely, I think it's written on them. From my experience, if you can feel any amount of ridge on the valve needles, they may by too worn. I bought these from Z1 and they fixed my issue. (Well that and tightening the one valve seat that I had forgotten to tighten. Doh!)

Are you still leaking on all four carbs? Did you try checking fuel height with the motor idling?

[mike1414]

It seems that way, Greg. I was going to just order a new needle and seat because, at this point, why the hell not? I've been running it, trying to fine tune it to get it to com around, but I'm just leaking gas all around Jacksonville! If the needle/seat doesn't do it, then I may well go with a different set of carbs.

Thanks, Hannibal for the input. From what I've read online, it seems as though stock is a 2.2, but I may be referencing the slide-type 26's. It is only 4 that is noticeably leaking. 1 has a slight drop from the drain screw here and there, but typically that drop stays on the screw for a few days, drips, then another forms over the coming days. Carb #4 is the only troublesome carb. Even #3 with the machine screw for a drain plug is working well! I did in fact check (via the tubing method) with the motor idling, but in all honesty it didn't feel like I was doing it right (didn't have a really solid seal on my hose, but I seemed to make due). Shall I just go with the new seat as well, or better yet, how can I tell whether or not a new seat is needed (if ever)? Also, does it matter the size of the seat?

Geol I do have air screws and have tinkered with them to correct the throttle response, but they are of little value with the issue occurring in my carb #4. I knew we shared these carbs (in a certain fashion) with the Kawi's, but didn't know there were such differences. It seems, though, that even the fine tuning pilot mix screw would have little value in this instance, yeah?

I mean there really is nothing else that I could imagine this overflow issue to be outside of float heights. What has been the MOST perplexing is that it just came on relatively rapidly. The fact that it was running decently (not overflowing, only rough throttle) --> stopped working --> carbs were cleaned (FLOATS WEREN'T EVEN SLIGHTLY ADJUSTED) --> all of a sudden I have bogging in the first 1/8th throttle and overflow of the 4th.