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paolo canevariMon Nov-29-04 06:12 PM

  
"one amal for commando o.k.??"


  

          

Hi there, I'm considering to mount in my Commando one amal 30 carb, insted of two,
I have a new Amal 30 and i would like to get the Norman Hide two in one mainfold in alloy.
Do you think one amal 30 is o.k.?? in that case should I change the jet? Or the cut in the slide??
thanks to all...

Paolo

  

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Ian WilsonTue Nov-30-04 02:52 AM

  
#1. "RE: one amal for commando o.k.??"
In response to Reply # 0


  

          

I've got no experience of a single Amal, but I fitted a single Mikuni onto my Mk3.

Best thing i ever did. proper choke mechanism, so no stinky fingers, easy starting and warm-up, stays in tune, about 10% increase in mileage, great and steady 800 rpm idle.

Can only think of one thing that isn't so much better than standard Norton: it needs a K&N type washable air filter, which doesn't look as 'factory' as the standard one. It probably works better though.

I chose Mikuni because the Amals wore out so fast (single or twin, you still get tuning difficulties) and I thought that getting fuel all over my fingers in the 21st century wasn't on. The Mikuni is very simple though, and a lot like an Amal in many ways.

I've had people say I lose a little performance. Well, maybe I do at the top end, or on the strip. But nowadays I'm a little bigger than I was, and a little slower I guess. So in everyday riding I never noticed any difference.

Hope this helps

Ian

  

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MichaelBTue Nov-30-04 09:55 AM
Member since Mar 18th 2009
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#2. "RE: one amal for commando o.k.??"
In response to Reply # 1


  

          

According to the INOA tech digest, 'A single Mikuni or Amal MK2 will run a Commando very nicely. A single Concentric will NOT flow enough fuel to run a Commando'.
Makes sense, if you compare a float bowel of a Mikuni or MK2 to a Concentric, the Concentric is significantly smaller.
I never done this, so I don't really know. But knowing this, I don't think I would spend the money to find out.

Mike

  

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Orlin PettitTue Nov-30-04 01:12 PM

  
#3. "RE: one amal for commando o.k.??"
In response to Reply # 2


  

          

The Amal Concentric can be modified to flow enough fuel. The trick is one that is used on race bikes. Use a keyway cutter to cut a slot in the side of the well that holds the float needle. The fuel then flows directly into the bowl instead of up and over.

When your new carburetor has about 10,000 miles on it, have it rebuilt with the Mikuni slide conversion. Then replace the needle jet about every 10k thereafter and your're good to go.

Orlin

  

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Ian WilsonWed Dec-08-04 08:15 AM

  
#6. "RE: one amal for commando o.k.??"
In response to Reply # 3


  

          

Hello Orlin,

All this is good, but if you're going to go to all the trouble of machining the carb and fitting Mikuni slides (more machining) why not just fit the Mikuni?

Am I missing something obvious?


My buddy has a 750 with a single Mk1 Amal. I look on with amusement as he covers his fingers with fuel and it still stalls just off idle..... Maybe his carb is shot...

Ian

  

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Orlin PettitThu Dec-09-04 12:08 AM

  
#7. "RE: one amal for commando o.k.??"
In response to Reply # 6


  

          

Ian,

Well, he has the Amal carb in hand. Once installed, should be good for 10k.

My experience with the Mikuni is good, but it's not entirely a bed of roses. As mentioned, It's a big lump and fitment of an aircleaner is always a pain. There isn't much room for the throttle cable either. The bike I have with a single Mikuni has the same fault I have seen on other Commando's with this carburetor. On occasion the float hangs and it will puke fuel out the overflow tube. The carb will dribble if the fuel tap is left on. I don't think the Mikuni likes all that shaking either.

There is an extended tickler button for the Amal. Of course fuel still dribbles out, but you don't get it on your hands.

At the end of the day, if you want clean and neat: get a Honda (though nobody will stop and ask you about your bike anymore).

Orlin Pettit

  

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geo46erTue Nov-30-04 10:07 PM
Member since Mar 18th 2009
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#4. "RE: one amal for commando o.k.??"
In response to Reply # 0


  

          

Greetings Paolo,
I too am in the process of doing the single Amal conversion.
Presently the only piece I have is the manifold. They are available from British Only for $66.00 online.
It was suggested to me to use the single throttle and choke cable from a TR6R triumph and to set it up like a mid 70's TR7V:

30mm venturi
280 main jet
106 needle jet
STD needle in middle position
3.5 slide cutaway

Hopefully it will be easy to dial in. The only thing I've been worried about is the clearence between frame and carb top.


justa thought,
G.B.

G.B.

  

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jimSat Dec-04-04 08:03 AM

  
#5. "RE: one amal for commando o.k.??"
In response to Reply # 4


  

          

Hi Guys, I run an 850 Commando with a single 32mm Amal, manifold came from Norvil along with 280 main jet, U1 needle, needle is set in mid position,slide is 3.5,chrome plated. The motor runs very, very well, no hesitation or fuel starvation,loads of torque. I fitted the new tank petcocks from British Bike Connection to ensure good gas supply -- the original petcocks do not flow enough fuel, I have had experience with Mikuni carbs. and my personal choice is to stay with Amal.As for clearance between the carb. and frame, this is not a problem using the Norvil manifold. Good luck , Jim.

  

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michael carterThu Dec-16-04 04:47 AM

  
#8. "RE: one amal for commando o.k.??"
In response to Reply # 0


  

          

I have 1970 Fastback 750 70,000 km. used regularly for once a
week run. Fitted a single 34mm Amal Mk 2 with manifold and KN
filter supplied by RGM motors UK. Have used this for last 3
years. Performance up to 5500rpm same as with twin 30mm . much
better idle and fuel comsumption. To get perfect performance
fitted slide with larger cutaway, and raised needle one notch
.

  

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GeneWed Dec-22-04 09:28 AM
Member since Mar 18th 2009
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#9. "RE: one amal for commando o.k.??"
In response to Reply # 8


  

          

Hello Michael,

My 74 850 has a 34mm MK2 and after fiddling with it for a few
years, it's just now beginning to become reliable. Inerested
to know how to tweak it a little for better performance. 

What, exactly, do you mean by "perfect performance"?
Which slide cutaway number are you refering to and what do you
mean by "raised needle by one notch"?

Thanks.
Gene

  

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mopamFri Dec-24-04 09:33 AM
Member since Mar 18th 2009
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#10. "RE: one amal for commando o.k.??"
In response to Reply # 9


  

          

Dear Gene. about your query about fitting of MK 11 Amal.
Firstly my bike is 1970 750 .Fitted with Boyer Ignition and
Electronic Regulator,belt primary drive, high output
alternator, oil filter conversion, and oil cooler radiator.It
has done 70,000 km.The motor has had only a top end overhaul,
the bottom end us unopened and original.The bike is used for
weekly club outings of about 200km on a year round basis, its
pretty reliable.I fitted the Amal Mk 11 at 30,oookm. It
arrived jetted and tuned for a standard 750 from RGM in UK.ist
problem was spitting back through the carb. Diagnosis lean
mixture when opening throttle. Slide changed with smaller
cutaway(I dont remember the no, its a few years back)problem
cured.Next problem was weak mixture  in regular riding, up to
half throttle diagnosed by plug colour.Bike was tested with
warm motor running at continuous speed at 1/3 to 1/2 throlle
and then cutting motor without closing gas.Needle was raised
one notch which cured problem. Similar method used to check
main jet size . The carb works cleanly from idle up to high
revs with no hesitation, easy starter from cold, good idle.
Fuel consumption is a reglar 20km/22 km per liter according to
riding conditions. Remember that I presume your motor is in
good condition. I also ride with tappet clearances 002 larger
than recommended as I live in a very hot climate.I have been
riding British Iron for 50 years, so have some experience. I
love my Commando, its a great bike to ride, sounds and looks
good. I am now building up a 75 model Interstate E/S and hope
iy will be as good as the Fastback

michael c

  

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