new here and new to Nortons

Hi Folks I am new here and new to the world the world of Nortons
I have a bmw r100 roadster I built from a box of oily cack and a guzzi lemans project on the go.
in a moment of madness I bought this ,so here is my 71 fastback, it has been standing for the last 12 years a couple of bits need a re'crome and the carbs need a good strip down and electrics need sorting as there are a few false earths.
My question to you chaps would be which electronic ignition shall I fit ? and what is the collective wisdom on fitting a single mikuni carb? I'm after back road usability rather than top end thrashing .

Hi, welcome. Use the search function, read until your eyeballs hurt :mrgreen:

chrisshropshire said:

My question to you chaps would be which electronic ignition shall I fit ? and what is the collective wisdom on fitting a single mikuni carb? I'm after back road usability rather than top end thrashing .

Click to expand...

I'll throw mine in; currently running a Pazon Altair, primarily for the idle stabilization, and a Mikuni 34mm single. This combo routinely returns 57-60 miles per US gallon in mixed driving, and pulls like a freight train up to 90 mph.

Welcome!
Nathan

Nater_Potater said:

chrisshropshire said:

My question to you chaps would be which electronic ignition shall I fit ? and what is the collective wisdom on fitting a single mikuni carb? I'm after back road usability rather than top end thrashing .

Click to expand...

I'll throw mine in; currently running a Pazon Altair, primarily for the idle stabilization, and a Mikuni 34mm single. This combo routinely returns 57-60 miles per US gallon in mixed driving, and pulls like a freight train up to 90 mph.

Welcome!
Nathan

Click to expand...

Like Nathan, I too run a Pazon. I like it because unlike a Boyer you don't have to cut off the wire ends if you ever have to remove the timing cover. Idle is as steady as a rock.
John in Texas

Just fitted a Tri Spark to test, I like the idea of the anti-kickback. Also, when fitted you can fit the S type coil bracket and tuck the coils further in which looks a lot neater.

chrisshropshire said:

I'm after back road usability rather than top end thrashing .

Click to expand...

Ya, sure... that's what they all say.

Anyhow, I have had many EI unit from many makers. So far the Pazon units seem to be the ones for me. Had the
surefire for many years and now their top of the line Smartfire.

I might suggest the Surefire for simplicity and economically priced and the Altair for bells and whistles.

Welcome .... take your time to read all the info here then make your informed decision .... remember to enjoy your project and not to let it drive you mad ..... in the end your "new to you" Norton will provide smiles for many years ...
Craig

Hi Chris ,

Congrats on your moment of madness , advice on E.I and Mikuni carbs ! You are in for a serious dose of inforumication any time now. All E.Is are good till they don't work and lots of Commandos run with Mikunis.

pete.v said:

chrisshropshire said:

I'm after back road usability rather than top end thrashing .

Click to expand...

Ya, sure... that's what they all say..

Click to expand...

Very true ,Pete . Where as I just want to hammer it till the spark plugs shoot out.

Jg

I like it because unlike a Boyer you don't have to cut off the wire ends if you ever have to remove the timing cover
Hmm. I run a Boyer and don't have to cut any wires to remove the cover. It also starts on the first kick, so I'm not sure how important the spark retard function, found on some EI units, can be. OTOH, it couldn't hurt, and may prevent an injurious kickback from the lever. If I were planning to get a new unit, I'd want this just for safety.

If I've correctly plumbed the collective wisdom with regard to carbs, it seems you might lose some very top end with a single Mikuni 34, that twin 32's might give a higher top speed.
I carry twin Amal 32's cause I like the stock look and don't mind the tuning routine, even though I don't ever expect to see anything over 80 mph. If you wanna find out how far over 100 mph your bike will go, maybe get the twin carb set-up.
Mikuni is well-regarded, reliable, widely available and understood. And of course, there is no need to synch.

Pazon Altair here, replaced early Boyer analogue. I'm quite happy with it.

Ask 10 folk on here about ign & carbs and you'll get 11 different suggestions... maybe 12 !

My preference is Tri Spark with dual coil as supplied by Matt at cNw. I don't know enough about coils and the best compatibility etc so went for a well proven combo.

Ref carb, it depends what you mean by 'top end'. My 36mm Mikuni stifled the motor above 5k big time. That's too low for me as I like to enjoy the pull of a Commando higher than that. IMHO its a shame to forgo the above 5k performance of a Commando as it is so good, and such fun! But, of course, this is not a 'right / wrong' discussion, as it all depends on the intended use and riding style of the owner, etc.

Personally, I put almost zero importance on fuel consumption with my Commando, it is a toy, for fun / pleasure only, and I simply do not do enough miles per year for fuel consumption to be a relevant point.

Most folk report favourably on Amal Premiers as all round good performers, although they might need some checking / fiddling before fitting, they look 'correct' too. Not tried them myself as I'm running 35mm FCRs, which I think are awesome!

The bikes have a higher top speed with twin carbs than a single Mikuni because they make more horsepower with twin carbs.
That horsepower is available in every gear.

Glen

worntorn said:

The bikes have a higher top speed with twin carbs than a single Mikuni because they make more horsepower with twin carbs.
That horsepower is available in every gear.

Glen

Click to expand...

true, But done properly as it was at Norton’s the single carb enabled you to run right down to 10 mph in top gear you cannot do that with twin carbs on standard gearing :!: :shock:

But done properly as it was at Norton’s the single carb enabled you to run right down to 10 mph in top gear you cannot do that with twin carbs on standard gearing

Click to expand...

And why would you want to do that? If you accelerate from that speed with out changing gears you are unduly stressing every component in the drivetrain.

JimC said:

And why would you want to do that?

Click to expand...

Quite. Isn't that why we have gearboxes?!

1st of all welcome to Nortonville and the forum, (Jerry Doe's wild ride) ha ha. I've had a boy or a Nortons since the late 70s and never had any problems with them. I've had a pazon on another bike and I've never had a problem with it. I replaced the Boyer on my 850 with a Tri Spark a few years ago and the first one failed in less than 1000 miles and I'm on the second one now. Fingers crossed. i've heard but don't know for sure that Tri Spark is now making a new model with the box mounted separately and not in the timing cover like the first ones were. This might be a better idea. As for carbs I'm no expert but I've run a single VM 34 Mikuni and I found it pulled like a freight train all the way to 100 miles an hour but it's uglier than sin and has no place on the British bike. I'm now running dual Amal premiers and love them

Congrats on your first Norton! While I myself am a fairly new comer to Norton and don't have experience with Amals or different EI units, my 69 750 came with a Boyer and Mikuni Carb and starts on second kick and idles with no problems. Lots of torque, no idea on top speed thou as here in Ontario we have a racing fine of $2000 to $10000 plus loss of license up to 10 years for doing 50 kmh/30 mph over the posted limit. One day thou.......
Cheers!

The two Carb one Carb thing is interesting. With the stock Commando you have an old hot rod that was made to run with twin carbs. The stock bike in 1970 could whip every other production bike.
Now it seems the masses want to convert those old hot rods to single Carb.
Is it really just so that you can run smoothly at ten MPH in top gear? That is the strangest argument ever, but I've seen it before in some of the old UK road tests.

On the BSA A10 forum, you have an old plodder bike with about 40 Hp or so on a good day. There was an optional two Carb head available for those, but they are rare. Unlike the Commando head, it wasn't a very effective two Carb head, but it did add a couple of much needed horsepower .
Those heads go for $1500-2000!
Most would love to convert their single Carb A10 to a twin Carb bike, even though the poor design of that head means that there won't be much, if anything, gained.

I get two Carb one carb whiplash going between the websites!

Glen

As far as the single/twin carb debate is concerned, it's time...

The man originally ask " I'm after back road usability rather than top end thrashing". Let's just go with that for carb choice.

Nathan

I know people who swear by the use of the original points as all you really need. Personally, I have a boyer microdigital on my commando, and have used the original boyer analog prior to that. I never had any ignition failures or any trouble with either. I'm too cheap to replace the boyer micro with a pazon or trispark unit that has anti-kickback timing curve to make kick back of the start lever less likely. I definately get the occasional kickback with my boyer IF the mixture is too lean when I kick it. Like everything with a commando, after a while you figure out a routine that works most every time.

Ultimately, the most practical thing is to see if your current carbs are usable or not. Those of us who have dual amals and have mastered their quirks by rebuilding them and learning about how they operate, are past the point of jettisoning them for a simpler single mikuni carb. My sleeved amals work fine. If you have dual amals, clean them up and give them a try, IF they don't work or you think they are the reason that bike idles poorly, then go from there... Who knows they might just work well enough to give you a starting point where the bike runs well enough to take some rides to evaluate where you are mechanically overall... That would be an encouraging place to start...