My Rapide has wee little 928 Premieres fitted. They seem to provide enough fuel for road use.
From 2004 to 2014 it had standard old 928 Concentrics fitted. They finally wore out , but the mileage was pretty high at that point.
With the old Concentric 928s fitted the bike ran at 115 mph indicated on the Sulby Straight. I haven't checked the speedo for accuracy at 115, however at 90 indicated the GPS says 92. So I think it's likely an honest 115.
It was enough to get by 5 twins that were racing ,all riders laid flat on the tank, on the Sulby Straight. The front runner was an immaculate Godet restored C Shadow, ridden by a young French fellow. I chatted with him afterward. He wanted to know what happened to my bike on the hill
His bike had stock carbs, although they might have been new.
It was a lot of fun, he passed me earlier on at a corner ( the Red Baron said do not pass on a corner or you will be expulsed from the Club!), I got by him on the Straight and then one plug overheated on the Mountain. He passed me again, this time me on a Comet running a 500 cc air compressor and going about 35 mph! He gave me a quizzical look as he flew past.
But fuel starvation wasn't an issue.
Must take a look at those float bowls to see if they have the notch.
The Premieres are as built but haven't been tested quite like that, although they have been used to pull up lots of long mountain grades 2 up in third at 80-85 mph, full throttle.
Jim Comstock has done a lot of dyno testing of stock and non-stock Commandos. He found that a good stock 850 makes 45-48 RWHP on his dyno, which is about on par with the claimed 58 bhp at crank.
They flow enough fuel for that ok, but if modified for more power then fuel flow does become an issue. On the other hand they like to blow up if you push them much past stock. So does the trans.
Glen
