Commando 850 - Back to twin Amal

Mine's a Dommie but same applies.  I have splitters on air and throttle.  I tape the splitters to the frame so they don't wander about.  Always tighten the cable adjuster locknuts on top of the carbs or they will go out of balance.  And fit chromed or hard anodised slides to reduce wear. 

clean out tank and before refitting, check petrol tap filters and measure flow rates through both taps into a measuring jug etc. One tap , properly working, is fine.

Of course you could just fit a single 932 and keep the other as a spare. That's essentially what I did with my Atlas. No regrets.

I suggest avoiding the standard over-complex system (a H-shaped layout with a pipe from each tap to the corresponding carb., linked by a cross-pipe: https://andover-norton.co.uk/en/shop-details/15631/fuel-pipe-assembly-h-style-1968-to-1973-).

Instead, acquire two 180° banjos from Burlen; connect the two carb.s with a short direct hose, and run hoses from the opposite sides of each banjo to the corresponding tap. This is neater and involves fewer potentially troublesome junctions. It also obviates having a hose full of fuel immediately behind the hot cylinder barrel, which has never struck me as a good idea. 

There's no need to open both taps; the system is fully able to supply enough fuel from one tap to both carbs. (This might not apply f you are going racing … )

There's a lot to be said for junking the standard set-up in favour of a twin-pull twist grip with cables direct to the carb.s.

First, one only needs to carry one spare cable instead of two.

Second, the spare cable can be taped in place so that, in the event of a breakage on the road, it can be quickly swapped into place without having to remove the tank.

I agree with Gordon, I have fitted a single 932 on my 76 Mk3 Commando, again, no regrets.

PS: first or second kick (Yes kick) MPG up from 44 to 68  mpg. No performance loss as I can feel.

I will believe a Politician before I take the factory (but newly refurbed by me) carb setup off my Commando. It is heresy to bastardize a Commando with one choking carb. Shame on you.

John Hudson used to tell me off, as he insisted that a split cable system allowed more accurate tuning, but I'm really happy with a twin-pull Tommaselli twistgrip and two cables. I've put in-line adjusters on the upper run and adjust the free play next to each other. The standard Commando cheap plastic 1 : 2 splitter is a dreadfully badly made thing that wears and hangs -up.

The Mk3 Commando fuel pipe set-up is available off the shelf and involves double banjos on each carb with a short connecting piece.

I turn on both taps to start, as flooding with the tickler seems slow with only one tap open, but not for normal running. Both taps open was needed on 25 mpg Tridents, but Commandos are better than that !

Martin,

I assume you are talking about the M******* conversion, as Norton made many single carb,  Amal twins.......As standard.

The acid test is that the Amal single carb works well. Standard or conversion.

Bit of a shoe horn but I believe the SU conversion works well too.

Still, each to his own. Strange we were discussing brake conversions earlier.

Hi Craig. I have a Tommaselli twin cable twist grip with quite high bars so there's quite a sweep of free cable from the tank to the twist grip. This makes tuning really difficult because the cables pull unevenly when you move the handlebars at idle, lifting one slide slightly and making the engine falter. This is really annoying because I cant trust the idle, especially if you are manouvering the bike with your feet or in traffic.  With a single cable and a splitter this can't happen. Both slides will lift equally. I suppose i could try having tons of slack in the cable but I'm just about to convert to a splitter (Wassel) because of this. 

It's so much easier to tune and synchronise carbs if there is only one. As for a single carb choking the engine, that's pretty far fetched. I used to race my 88 on a single carb (up against Commandos) and still found myself on the podium.

You could fit the Don Pender single cable gantry system, works well on my 750.