dual mikuni vm32 750 combat (2008)

Tornado said:

Why dont we hear of dual mik setup more often? Seems one of the downsides to fitting the single mik is some performance loss. So the duals should eliminate that plus give the greater reliability of the Japanese build.

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The biggest issue is that they stick out like the carbs on a T120, but on the Norton they greatly intrude on the riding position of the operators legs; other than that they will offer better fueling and performance, however, the manifolds are becoming hard to find.

Best.

Glad I hung onto mine if that the case ...

RoadScholar said:

The biggest issue is that they stick out like the carbs on a T120, but on the Norton they greatly intrude on the riding position of the operators legs; other than that they will offer better fueling and performance, however, the manifolds are becoming hard to find.

Best.

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MikuniOZ still sell them..

I totally agree that the miks are better made carbs than the OEM Amals as far as materials/longevity are concerned. But in comparing a current 32mm Mikuni with a current 32mm Amal Premier, I don't think the Mikuni has a quality (or any other) advantage over the Amal. And...the Amals fit properly.

MexicoMike said:

I totally agree that the miks are better made carbs than the OEM Amals as far as materials/longevity are concerned. But in comparing a current 32mm Mikuni with a current 32mm Amal Premier, I don't think the Mikuni has a quality (or any other) advantage over the Amal. And...the Amals fit properly.

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hmmm, that might depend on your definition of ‘quality’ Mike.

I don’t see to many posts concerning swarf, wrong jets, poor machining, mystery faults, etc from the Mikuni brigade...

MexicoMike said:

I totally agree that the miks are better made carbs than the OEM Amals as far as materials/longevity are concerned. But in comparing a current 32mm Mikuni with a current 32mm Amal Premier, I don't think the Mikuni has a quality (or any other) advantage over the Amal. And...the Amals fit properly.

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Fast Eddie said:

I don’t see to many posts concerning swarf, wrong jets, poor machining, mystery faults, etc from the Mikuni brigade...

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The Amals do fit better, the manifolds for the twin Mikunis, with some variation/exception, put the Miks in a position that interferes with the riding position.

Calibrated parts for the Amals are crazy expensive compared to the Mikuni equivalents. In my experience Mikuni offers a much greater range of tuning options which allows the experienced tuner more choices, but can cause the well intentioned troglodytes mass confusion and frustration.

Best.

Old thread

Is the horse still alive, or in need of a few more lashes? I've got a whip.

Amals are good WOT when synced.

No interference with the riders legs with the twin Mikunis on my bike. My manifolds are shade tree engineered one offs. The Mikuni carburetors are splayed out and definitely not as close to each other as Amals. Only annoying issue with the Mikuni carburetors on my ride is the idle air mixture adjustment screw is on the wrong side on my left hand (sitting on the seat) carburetor. It is facing the middle between the pair and a PITA to get at. They are old though, and Mikuni may or not have been able to address that. Also not a real fan of the choke lever on the right hand carburetor pointing the wrong way, but it does work. Still have the "NOT FOR AIRCRAFT USE" and Sudco stickers on the carburetors. Hard to believe they have lasted as long as they have. Considering whether or not to install hose barbs for a 1/8th inch balance tube in the intakes and see what happens. My bike idles like it has a big cam in it. Its an SS in a ported head.

I still have the 930 Amals I bought in the 70's boxed up. I wouldn't put them on a bike I wanted to ride after using the Mikunis. I would put them on a restoration if I had one I was going to sell. Installed Mikuni conversions are not as good a selling point as having the stock Amals on and offering the Mikuni conversion as an extra. End of babble

The Mikuni VM32 I have are marked left and right , I think (been awhile) but the choke lever orientation can be adjusted by removing and remounting in position you desire , or at least the ones I have , from Sudco as well .... moving the choke not difficult ....

Schwany said:

the idle air mixture adjustment screw is on the wrong side on my right hand (sitting on the seat) carburetor. It is facing the middle between the pair and a PITA to get at. They are old though, and Mikuni may or not have been able to address that. Also not a real fan of the choke lever on the right hand carburetor pointing the wrong way, but it does work.

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The 30, 32 and 34 VMs have the same body and, to date, the only feature that makes them right or left hand is the slide height adjustment screw, all other features are biased to the right.

Cable choke conversions are available.

Best.

Craig
Mine are right and left in the sense that the idle set screw is on the outside where it belongs and the slides are right and left.

The levers cannot be reversed or turned around on my set. Mechanically impossible without redesigning the mount. There might be levers that I can buy that can be turned around. Have not looked into it. Thanks for the tip.

RoadScholar
Thanks Good suggestion
I'd really have to want to do that more than I do at this moment. I like the simplicity of what I have. It's just a little inconvenient as is. I have my idle set really low and it takes a minute or 4 to get the motor to idle when its stone cold. I have to keep the throttle open while I shut the right side choke off. I'm sure it looks darn comical. Not looking for tuning advice in case that's about to happen. I like the engine brake I get from the low idle.

FWIW, i found this a good guide for tuning Mikuni carbs

http://www.vintagebikebuilder.com/mikuni-tuning-and-jetting-guide.html

The VM34 mounted at this time gives choice of choke lever orientation too , thought feature was across the board , sorry ....

Craig
No reason to be sorry about good advice at all brother. It was a good tip. It made me go look, cuz I was hopeful. It just didn't apply to my set.

A couple of weeks ago I pulled out some Mikuni VM32's and manifolds I had stored away years ago.
I was thinking of putting them on my 1972 Commando. It looked as though the ignition would have to move if I installed them. So I put them back in the box.
Anybody confirm the ignition would have to move? And where would it be moved to?
The stock ignition is attached to the rear plate of the air cleaner, and sits near the left hand side cover.

RoadScholar said:

The biggest issue is that they stick out like the carbs on a T120, but on the Norton they greatly intrude on the riding position of the operators legs; other than that they will offer better fueling and performance, however, the manifolds are becoming hard to find.

Best.

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Actually looking at the white bike in the video again, the Mikuni's don't stick out at all, and you can see here how the ignition switch has been re-jigged. I reckon you could probably get the RGM narrow ham can air filter to work there as well, so you wouldn't even need to move the switch.

The white bike had 28mm carbs though, which IIRC are a smaller body than the 32/34mm more usually fitted to Commandos.

Perhaps their smaller size helps them protrude less? Perhaps that’s why they were chosen?

The benefit of Mikunis is the adjustability they offer for tuning.

The downside of Mikunis is the adjustability they offer for tuning.

Apart from the manufacturing quality demonstrated over time, they are great for racers and others willing to put the time in, but can be equally bad news for most users who are generally not ready to invest time on research and adjustment/testing! I came by my first set of Mikunis from a guy who tried them on his Commando and could not get them set up how he wanted, good for me as they came with a number of alternative jets and even slides.

Amal Premiers solve some of the issues of earlier Amals, look the part for a relatively standard bike and have known sets ups for standard ish bikes. Good solution.

If you want a single carb for simplicity and reliability the Mikuni adherents have accumulated enough data to help you get close with no big issues. Good solution.

If you are going racing, twin Mikunis work from 32mm to 36mm depending on engine spec and a baseline to get testing with can be sorted fairly rapidly, testing and making improvements over time, but best done on a dyno, which is not something a lot of road users want to do!

Unlike more modern flatslides etc. VMs are eligible for pretty much every classic racing series. Good solution .

Carburetor tuning has not changed in my lifetime. Articles on carburetor tuning theory written 60 years ago are the same as articles written today. I use an old butt dyno and my ear. Yeah I know, never that accurate. Dyno tuning scares me though, and would be a big waste of time and money in my case.

That white Norton must be a trailer queen, or somebody is really good with a cleaning rag. Beautiful specimen.

Schwany said:

Carburetor tuning has not changed in my lifetime. Articles on carburetor tuning theory written 60 years ago are the same as articles written today. I use an old butt dyno and my ear. Yeah I know, never that accurate. Dyno tuning scares me though, and would be a big waste of time and money in my case.

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You want to read the plugs, or better yet, get an AFR gauge

Schwany said:

Carburetor tuning has not changed in my lifetime. Articles on carburetor tuning theory written 60 years ago are the same as articles written today. I use an old butt dyno and my ear. Yeah I know, never that accurate. Dyno tuning scares me though, and would be a big waste of time and money in my case.

That white Norton must be a trailer queen, or somebody is really good with a cleaning rag. Beautiful specimen.

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Actually it has changed! Not the fundamentals, but carbs meter fuel, and in your lifetime fuels have changed a great deal. And the target fuel air mix has changed with it, at least a little.

Main issue coming from this is the ability to read spark plugs. And the availability of tools to check fuel air ratios, which are now more reliable than plug readings.

Most of us struggle to read a plug well when using pump unleaded fuel. Get some lead in there and your plug reading 'skills' will improve a great deal.

Not sure why dyno tuning should scare you, or is it that you want your independence, and trust yourself more than some young guy with a computer? I understand that one.

I haven't used a dyno much, but when I have it was in the hands of a guy at least as old as me and with much more skill and dyno time that I will ever get. His first recommended change gained 3 hp!

It can save so much time, and therefore pay for itself, particularly when that is expensive track time!