Amal Mk2's Or Amal Mk1 Premier's?

Hi all, at the stage where I need a set of good carbs for Bike # 2 Project.
Initially went down the JS Flatslides (have a set on bike shown in avatar) or Lectrons, but classic racing rules in NZ negate both these types.
Have been onto Burlen(Amal) about 34 mm Mk2's and they have informed me that due to new tooling , these wont be available for some months.
I need them mid January.
So thought maybe a set of 32's may do.
What are the forum members thoughts on running 32 mm Mk2 's or 32 Mk1 Premiums?
850 motor, 0.040" oversize, Black Diamond std Vv's, 10.1 CR
Most of the tracks the bike will be used on don't have very long straights so looking for lots of midrange
Have modified std C'do rear hub for quick change sprockets so dont have to take the clutch off to change gearing at the gearbox.
Regards Mike

Brooking 850 said:

Hi all, at the stage where I need a set of good carbs for Bike # 2 Project.
Initially went down the JS Flatslides (have a set on bike shown in avatar) or Lectrons, but classic racing rules in NZ negate both these types.
Have been onto Brulen(Amal) about 34 mm Mk2's and they have informed me that due to new tooling , these wont be available for some months.
I need them mid January.

Click to expand...

Gooday Mike,

Petrol right ? Alcohol is better.

On a good 850 the 32mm will run well with excellent midrange up to about 5500rpm. Full throttle operation there really nothing between the MK 1 and MK 2 up to 5500.

I would try the MK 1 32mm if you have a set laying around and see how they feel until the the 34mm MK2 turn up. The 34mm Mk 2 will run better above 5500 rpm.

MK 2 is the choice for classic racers here.

I use 34mm MK2 amals with tapered ports. They are mounted on Mick Hemming's manifolds and moulded rubbers, so there is no internal step. I ordered the carbs with alcohol kit so the needles and seats, floats are correct, but the main needles and main jets were absurd when I received them. I'm using Amal 670 main jets, and I made my own needle jets out of brass hex to 0.117 inch using number drills. I use 6DP6 mikuni petrol needles, and set them so that if you lower them one notch the bike coughs as you vary the throttle in the twisty bits. The bike has a two into one exhaust and a standard 850 cam which has been advanced 15 degrees. It pulls like a train, and even with a 4 speed close box is very fast. I suggest that if you intend to race, you should use methanol fuel it it is permitted. Your jetting is not so critical if you get it wrong (too rich) . But if you want to get the most out of it, it is as difficult as petrol to get right .
I know this might sound complicated, but because of my years of experience with Triumphs, I was able to go almost straight to the best jetting for methanol fuel. What I never expected was how well the crappy old commando motor responded. Hope you have as much fun as I've had doing this stuff .

The Amal Mk2's outflow the concentrics by a large margin. Jim

'The Amal Mk2's outflow the concentrics by a large margin. Jim'

Jim, I never thought about that as I was always trying to get the motor to be more torquey. I could have easily gone for radical cams, separate exhausts and hemisphered heads , but I didn't believe the bottom end would cop it without a billet crank and steel rods and much lighter pistons.

Thanks all.
acrotel, yes thanks and have read your posts on methanol, just need to get started and bugs sorted on bike beefore i head down that track.
can get a methanol kit eventaully.
Jim, as in my emails, can't get new 34's, so will give the Mk 2 32's a go.
Anyone in the States have a new set?
Negotiating with a forum member over a set of Mk2 32's but they are second hand . No deal struck as yet.
Regards Mike