carb conversion

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I just completed a switch to a single Mikuni flat-slide (TM 34) after repeated attempts to get my new Amals to idle consistently. What a difference!! No more messing with float levels, sticking slides, tickling before start-up, synchronization issues and, best of all, and end to poor idling. Starting couln't be easier also. Pull up on the choke knob, kick and start! There's a thumb-dial that fine-tunes the idle in one simple motion...set it to 1K rpm and it stays there ALL DAY. As far as performance goes, I can't detect any loss in acceleration...it still pulls extremely hard...crusing at 40 is smooth as well as steady highway speeds of 75+. The very top end may be affected, but I don't ride the old girl like I did in my 30's so I'm not sure if top speed has been diminished. IMO it's the best upgrade I've done to date.
 
Did you use a kit? Where did you get everything? I, too, am ready to give up on the Amals.
 
Thanks for all the responses, one question: are they jetted properly out of the box or will I need to mess around with the jetting?
 
The MAP kit is a Mikuni VM, round slide. Cmessenk posted he is using a Mikuni TM, flat slide. The flat slide is a big improvement over the round slide.
 
Hi Roady,

Re-Jetting? Yes, you will inevitably have to. Never had one out of the box that was right. So better to specify something useable when you order. Here's my tip for an 850 Mk2.

Main Jet 240

Needle Jet P2 or P4

Needle 6DH3 or 6DH4

Pilot Jet 35

Air Jet 1.0

Slide 3

Mick
 
Hey Guys,

Seeing we are on the subject of Carb conversions! does anyone out there have any specs for the approx jetting of running 2 off 32mm or 34mm Mikuni VM carbs on a 850????


Brewer.
 
The most frustrating and yet perversely rewarding thing about my commando is knowing and seeing it has dare i say classical twin carbs. Once cleaned and jetted and adjusted correctly with the forums help I have found them a pleasure to deal with. Cheap easy to fix and original. That is my opinion FWIW
 
Rockyrob said:
The most frustrating and yet perversely rewarding thing about my commando is knowing and seeing it has dare i say classical twin carbs. Once cleaned and jetted and adjusted correctly with the forums help I have found them a pleasure to deal with. Cheap easy to fix and original. That is my opinion FWIW
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I agree, I ran Amals for years. But in my dotage I've become compulsive. It got to the point that I really began to imagine that the Amals weren't sync'ed, it became an "issue". So I got a VM34 single and it really is a set and forget item, like electronic ignition. I've kept the Amals and points if I ever become compulsive about originality.

If they would just make some detail changes like using an actual accessible airjet, decent metallurgy, thicker walls on the throttlebody, chromed brass slide, ect., I'd go back. For now, a single Keihin FCR is tempting me. Would it fit? I wonder..
 
I have a friend here in Florida who has worked with Sudco for some time now to create a TM 34 Mikuni flat-slide "kit" specifically assembled for 750 and 850 Commandos. At my friend's request, Sudco tested the various components (i.e. main jets and needles) to come up with an optimum package for the Commando that comes pre-jetted and with the proper needle. The "kit" includes the Tm 34 flat-slide, manifold, gaskets, rubber connectors for the manifold and air filter, a 90 degree fitting for the throttle cable and two choices of air filters (cone style or pancake style for the vintage look).

Anyone interested in contacting the person who helped me out can reach "Dave" via: neuxstone@aol.com

Cheers!
 
Hi,
In my garage I have a set of Mikuni TM34 that came from one project and a pair of manifolds for commando that came from another project. I have never started to try out the jetting for this setup so if someone has a starting suggestion for a pair of TM34 on a 850? (or if not I can start with a suggestion for a single TM34 on a 850) I would be grateful!

Cheers,
Peter
 
:arrow: I am the SUDCO Dealer that CMESSENK mentioned earlier.
I own 2 Commandos. A '72 750 and '74 MKIIa. While I think it a shame to mess with the old technology, if not only just for the sake of prosperity, I had to be convinced kicking and screeming all the way to change to a SINGLE Mikuni setup.
A friend had converted a "other brand" bike to a flatslide, from the standard VM roundslide with remarkable results, so I was determined to run with the TM rather than the VM if I was to make the switch. The conversion kit is identical with the exception of replacing the VM 34 to TM 34 single carb kit. Having one carb it would seem the price should be half of the 2 carb kits; however the manifold is quite expensive, and 2 carbs are simply not necessary unless you either race, or love to screw around trying to keep them syncroed.
Let's face it, there are plenty of other things needing constant attention on the old girls!
The results are remarkable! This kit makes your bike run like it has fuel injection.
It comes as a "kit" inclusive of the 2/1 manifold and carburetor jetted for your application. If you want the air filter you order those separately because of the variety of types. I order all the necessary jets, slide, and needle. To dial it in you may have to move the needle a notch or two down, as it err's on the rich side.
After installation your bike will idle perfectly and usually start first kick. The choke is an enrichening circuit and the idle set screw is huge, so you can turn up the idle for wam-up. I also noted better fuel economy once I dialed mine in, which may not seem a big deal, but it gives you more distance per fill-up on the roadster tank.
I would suggest a 90 deg elbow that fits on the carb cap, and throttle cable kit that will have to be assembled/soldered to the correct length, and a "pancake" air filter to keep a classic look.
One other bonus that bears mentining...my attached garage doesn't stink like gas, and neither do my hands anymore :idea: .

I'm not real sure if the moderator will be pleased if I solicit these kits here, so I will just say for the sake of the betterment to the Marquee, I have them available if you need. Contact me (Dave) directly at neuxstone@aol.com
 
Does a TM34 still run out off puff about 100mph like the VM34 does,or does it just pull even better through the mid range? :?:
 
Not sure I understand the question..."still runs out of puff"?
Maybe you can clue in the other readers too...
 
splatt said:
Does a TM34 still run out off puff about 100mph like the VM34 does,or does it just pull even better through the mid range? :?:
Click to expand...
neuxstone said:
Not sure I understand the question..."still runs out of puff"?
Maybe you can clue in the other readers too...
Click to expand...

A single VM34 lacks topend power{runs out of puff} I was wondering if the TM was any better, I love the way it runs with the VM & I don't want to be thrashing it at 100mph every were, but if there is a performance gain at no cost that may be worth while looking into.
 
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