MPG?

[mfremlin]

Just done 155 miles at varied speeds including a thrash down the motorway for 30 miles on a Commander and burnt 17 Ltrs of fuel which equates to 42 mpg. Previous to this I did 108 miles using 13 Ltrs of fuel and at no time exceeded 4000 revs which equates to 37.77 mpg. The last stint was done using B.P's finest so perhaps the quality of fuel makes a difference?Mark.

[Charles Wilson]

David Garside, "Development of the Norton Rotary Motorcycle Engine", SAE Paper 821068:"The full load SFC is some 10% or so higher than necessary for best torque. This is due to a slightly rich mixture being supplied in order to give some additional internal cooling for this air cooled engine..."Sometimes, I quote scripture without having the Proper Vestments but in reading this thread, I wonder if maybe the carbs may be a little too rich on some of these bikes?CW

[Malc]

That fits in with the rich mixtures found on the 25 or so police bikes I looked after. After a few thousand miles, the blanking (tamper proof) plugs were removed from covering the mixture screws and the mixtures were then set asper workshop manual. This involved setting the bike to run on one rotor at time (while earthing the other plug so as not to damage the ign unit) and adjusting the mixture until the engine speed was at it highest steady rpm, then turning the mixture screw in a half turn to richen back up, (for better throttle response).Eventually found it was quicker to do a basic set up with a fast tickover while on both rotors then road test without the side panels fitted and adjust according to the engine response, if the engine runs too weak, there is poor throttle response especially on larger or fast throttle opening. I had a regular lay-by to pull into, as the engines are quite happy running a bit rich I would weaken off to the point of poor pick up and then richen up quarter tun increments until throttle response was right all through the rev range.The bikes averaged aboput 45 mpg as did my own road bike.I did take a not of the new jet height figures for a couple of bikes but have since lost them but when a couple of bikes that were running well were put on a CO meter, they were still rich at 4.00 to 4.5%Malc