Mikuni carb

Any advice on switching from 2 amals to one mikuni on 1973 750 commando

My opinion is don't, Amal carbies are so simple, I don't know why people have so much troubles with Amal carbs, they do need to be maintained same as any other carbie, yes things wear, depends on how many mile you ride a year, how you ride your bike but going single carb you lose a lot of performance, over the 50 years of owning my Norton I gone down the road of changing the carbs on it but in the long run I have gone back to my old Amals and have found my Norton runs so much better with them, my 850 motor isn't stock built for the Featherbed frame, cam and head work, the Amals are jetted right for my motor performance and with the Joe Hunt magneto it starts first kick every time whether cold or hot, they are easy to maintain, easy to tune and I am no tuning expert but I do know my own bike.
But of course everyone is different and ride differently to how I ride, but if I was going to go down the road of new carbs a set of premier Amals be the go and they look better as well, tuned right they are a reliable carbie, simple to work on, jetted right for your motor and if timing is set right will be a one kick starter every time.
Pay a bit more and put on a set of Premier Amals and your Norton will love you for it, this is of course my opinion.

Ashley

The Amal premiers are way better than the old ones. And they look the part on Nortons. The downside is PRICE. And the need to synch them up and stay on top of them.
A single Mikuni is easy to start, just set them on fast idle, may or may not use the choke, and give it a good kick.
You will probably have to remove the ham can filter and make a new position for the key switch. Someone, somewhere, makes aham can to solve this problem.

I just acquired a '72 as well and thinking about switching. Especially after just hassling with the stock filter and the inner manifold fasteners. At 73, easy is the name of the game for both maintenance and starting. I read the single Mikuni helps in both departments. Have also read good things about the CNW kit.

Any comments? Appreciate the help from those more knowledgeful than I.

Mikunis are fine instruments, very well made. But you do have to be careful to not buy counterfeit these days.

A Mikuni that is set up well, will run very well on a Commando.

A Mikuni that is not, will not.

And… the same applies to Amal’s, set up right a pair of new Premiers will run superbly on a Commando and definitely outperform a single Mik above 5k rpm ish.

A single Mikuni kit will be cheaper than a pair of new Premiers. That and being easier to get on / off realistically the only advantages IMO. So if these issues are important to you, and performance above 5k rpm is not, a Mikuni makes an awful lot of sense.

I don’t run either now FWIW, I run FCRs as sold by cNw.

You will, of course, get many contradictory opinions on this topic. At the end of the day, it’s your call.

My 1973 850 came with a single Mikuni when I bought it.
It's very easy to start with its lever choke that is on the left side of the carb. I flick the choke on, start the bike ( I have an Alton Estart) and the moment it fires, I flick the choke off. It runs very, very poorly if I leave the choke on.
Interestingly, it did not idle well after starting when it had the Boyer ignition that came with the bike. When I changed to TriSpark ignition, and did not touch anything else, suddenly the engine idled well right after cold starts.

Dennis

My pile-O-parts N15CS came with a VM34 and the 2>1 adapter. I also have some Amals, and thought about running them, but the Mikuni is so good I that don't want to spend time and money to change for some performance increase. I'm not looking for speed out of the Norton; I have other bikes for that. I think having a 7.5:1 compression engine and tall gearing makes the Mikuni setup right for the task, whereas a Commando is a 'wring it out' vs. ride the down-low torque of my bike. I rarely go over 4K RPM, don't need to.

Advice ?
Get off the choke ASAP on the Mikuni . It's a rich situation , best flipped off soon . The manifold was not meant for high RPM's .
Also : attaching the manifold to the head , the 4 Allen screws need to be tight , with blue Locktite on the threads .

Torontonian said:

Advice ?
Get off the choke ASAP on the Mikuni . It's a rich situation , best flipped off soon . The manifold was not meant for high RPM's .
Also : attaching the manifold to the head , the 4 Allen screws need to be tight , with blue Locktite on the threads .

Click to expand...

Yep, or kick it over with the key off and enrichener on, that is all it takes on mine if it's cool out.

I believe that COMNOZ had stated that a 36 manifold worked better than the 34 manifold with a 34 carb.