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
.

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

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