VM26 Carbs with high fuel level
- Nessism
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VM26 Carbs with high fuel level
08 Jan 2024 10:40
I've seen more VM26's with high fuel level that I care to shake a stick after. The floats are typically adjusted with the tang either flat, or slightly down, which lifts the float, and drops fuel level. The problem get serious when the float tang is bent down to the greatest extent possible, and yet the fuel level is still too high. At that point, it's time for new float valves. I typically use Keyster brand. And even with these parts, it's often necessary to adjust the float as high as possible.
Question is, how much does the float itself contribute to the problem?
I've bought aftermarket floats and used those, but they don't inspire confidence, and are often heavier than the used parts they are replacing.
I've found a reference connecting the OEM Float PN 16031-031 to Mikuni VM24/171 floats, which are made from brass. Has anyone ever used these brass floats in their VM26/VM28 carbs? I'm starting to wonder if that would allow the float to be installed with the tang flat, like the carbs were when first built?
Question is, how much does the float itself contribute to the problem?
I've bought aftermarket floats and used those, but they don't inspire confidence, and are often heavier than the used parts they are replacing.
I've found a reference connecting the OEM Float PN 16031-031 to Mikuni VM24/171 floats, which are made from brass. Has anyone ever used these brass floats in their VM26/VM28 carbs? I'm starting to wonder if that would allow the float to be installed with the tang flat, like the carbs were when first built?
Ed
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- Warren3200gt
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Re: VM26 Carbs with high fuel level
08 Jan 2024 13:15 - 08 Jan 2024 14:18
I've probably readjusted floats back to there original specs a 1000 times.Everybody just adjusts tangs without looking at the angle the floats are sitting compared to the hinge. The hinge plate when new ran through the float center line. Most have the float hanging down from the center line now after years of abuse.
You can of course adjust this point either up or down so that the tang sits level to ensure the needle travel is pushed veticle by the tang and not at an angle which can cause non sealing valves.
You can of course adjust this point either up or down so that the tang sits level to ensure the needle travel is pushed veticle by the tang and not at an angle which can cause non sealing valves.
Last edit: 08 Jan 2024 14:18 by Warren3200gt.
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- Mikaw
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Re: VM26 Carbs with high fuel level
08 Jan 2024 15:32 - 08 Jan 2024 15:33My first procedure is this also. I go thru all of the floats and bend tang flat and make sure the arm (float plate as Warren calls them) are 90 to the float. Then I hang all floats on the hinge without bowls on and adjust till all hang down the same amount this gives all equal starting points. Then I adjust with the clear tube method.I've probably readjusted floats back to there original specs a 1000 times.Everybody just adjusts tangs without looking at the angle the floats are sitting compared to the hinge. The hinge plate when new ran through the float center line. Most have the float hanging down from the center line now after years of abuse.
You can of course adjust this point either up or down so that the tang sits level to ensure the needle travel is pushed veticle by the tang and not at an angle which can cause non sealing valves.
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Last edit: 08 Jan 2024 15:33 by Mikaw.
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- Nessism
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Re: VM26 Carbs with high fuel level
08 Jan 2024 17:29 - 08 Jan 2024 17:49I don't know about this. I've never seen a float like you describe. Look at this image from the service manual...The hinge plate when new ran through the float center line.
Ed
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Last edit: 08 Jan 2024 17:49 by Nessism.
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- asphalt900
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Re: VM26 Carbs with high fuel level
09 Jan 2024 02:09
Just FYI, those VM24/171 brass floats will NOT work in the 4-cylinder VM carb castings. They are approx 64mm width on outer brass float bulbs whereas the original ones are 53mm so too wide. Also some of thoses H1-2 brass floats did not have the hang tang. I guess one could unsolder the individual bulbs and move them inward about 5mm on each side but not really worth the effort.
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- asphalt900
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Re: VM26 Carbs with high fuel level
09 Jan 2024 02:22
Also something noteworthy. But first follow Warren and Mikaw's inspiration about grabbing the brass as it enters the float material and bend up/down. But you can also stack an additional 1-2 float seat gaskets under the float needle seat, anymore and you can bind the pivot action. This, as mentioned, will allow the float adjustment tang to rest perpendicular to needle spring pin.
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- DOHC
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Re: VM26 Carbs with high fuel level
09 Jan 2024 05:55I don't know about this. I've never seen a float like you describe. Look at this image from the service manual...The hinge plate when new ran through the float center line.
The plate may not go through the center of the float, but I have definitely looked at the black float piece relative to the plate and decided that it was bent and needed to be straightened.
How about the VM29 smoothbore float? The 29mm used brass floats, and JetsRUs lists the Mikuni part number as "VM26/260", which sounds like it could fit the VM26/28? Has anyone tried to put a VM29 brass float in a VM26?
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- asphalt900
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Re: VM26 Carbs with high fuel level
09 Jan 2024 06:57
That's exactly what You would want to try, smoothbore 29 brassies. Greg has a set he'd just "found", i'll call him to verify
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- Nessism
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Re: VM26 Carbs with high fuel level
09 Jan 2024 07:30
I've seen lots of floats with bent plates. You can usually see the bend visually, and the black float pods won't measure the same height. It's easy to adjust them by grabbing the pod and tweaking as needed. And speaking of tweaking, you can adjust float height that way too, instead of bending the tang. I typically only do that for small adjustments, if the tang is already down some.
Ed
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Re: VM26 Carbs with high fuel level
09 Jan 2024 07:42
I went through this years ago and still am. When a brass float developed a leak I took out the black floats from my 28's and put them into my 33's. I found they were narrower but they fit the only problem was the "hang tang" as I had to bend them down for the bowl to fill. Aside from that they worked well for a couple years until I bought new ones from jetsRus.com. When new they wouldn't let enough gas in to fill the bowls. Knowing that if the tang is bent too far it would cause the needle to cock sideways and cause them to leak. There is a fine line of adjustment to have the float angle to work while having the tangs almost flat as to not have a leak. I set the float angle to "ball park" the setting and bend the tang for a fine setting. Even then it's trial and error to get them where they will fill the bowls quickly and to the level I'm looking for. The new floats weren't plug and play and once set they work well. I'll be getting new needles and seats but these have screens on them so the 28/26 seats won't work on them but the needles do.
Mike at jetsRus is a good guy to work with and he got me the parts I needed at a fair price but sometimes they will be on back order then appear in my mail box.
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Mike at jetsRus is a good guy to work with and he got me the parts I needed at a fair price but sometimes they will be on back order then appear in my mail box.
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- asphalt900
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Re: VM26 Carbs with high fuel level
09 Jan 2024 07:54
Absolutely, I have bags of the originals. But honestly ya might be over thinking this whole concept. As an inverted assembly, provided the spring in the needle has enough tension, tops of the floats should sit somewhat parallel to the jet holder casting tower. If You constantly experience wet fuel levels outside parameters then bend/shim accordingly. Of course you know this but check float side-to-side play at the furthest section away from the needle/seat, your flavor of gasket installed, for interference in action. And although rare, float material has been known to saturate, have never experienced it but i know it can happen. Thinking i mentioned to Matt but i have TUBS of this VM Mikuni stuff if it helps You with Your hobby.
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- asphalt900
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Re: VM26 Carbs with high fuel level
09 Jan 2024 10:28
Here's some crazy for crazy thinking "outside the box" stuff if one would want to try it? I've been doing it for years with great results. I've not bought a paper bowl gasket for years either. I o-ring the bowls, no more brown staining down the sides. Use a Float set from a Honda VF750 82-83. Yes it's Keihin and one would think the diameter/pitch of thread would be different but interesting enough it's the same. This allows a bump to "newer" stuff, viton tipped needles compared to the brass/steel of the originals. Just a slight modification to the protrusion whereas Honda used a small screen, other than utilizing the "hook" that goes around the float tang to needle, you're set.
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