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On a recent thread titled breakdown Peter asks for jetting for a single Mk 1 Concentric. The problem with this set up is that the float bowl/needle will not flow enough fuel to feed both cylinders at higher throttle settings. It is possible to machine a slot with a woodruff cutter below the surface of the float jet and this may improve things but higher throttle settings are going to run short of fuel and this will not be fixed by bigger main jets. Mk2 Amal and Mikuni VM do not suffer in this way. (I've had twin mk1 amals, single mk1 amal, single mk2 amal, SU, Single Mikuni VM and finally twin PWK flat slides in the last 41 years)
Hmmmmmmmmm, I had issues w…
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Hmmmmmmmmm, I had issues when I first put my 850 Mk3 Commando onto a single 932 Mk1 Amal. Perhaps it depends on the bike but after a couple of e-mails to John Dunn, who runs this arrangement with no issues, all was resolved.
Main corrections for me was to change from a 270 main jet DOWN to a 260, a stay up float to increase the fuel level and change the spray tube to something more appropriate.
Starts first kick too, using standard plugs, Esso Supreme E0 petrol, Boyer electronic ignition, fitted in 1988 and Classic 20/50 oil.
The icing on the cake is 68 mpg average and a very steady tick over! If your bike is a 750, then some of my settings will not apply.