When I built the rear hub for the twin racer I used close tolerance titanium aircraft bolts, and reamed the holes one at a time. These bolts also come in over sizes so you can go slightly larger if needed. The whole assembly was very light, when you consider 20 bolts with nuts.........It is lots of small changes that make for a light weight machine........I'm sure Phil told me the bike came in at 152 kg's.
The Vincent engine with exhaust system is right around 100 kgs.
The 1360 with its heavier Molnar cases and porkchop crank but lighter Newby belt drive was about the same weight as the 1000 engine +-2 lbs
I saw mention of building a racer at 130 kgs. This would be a feat!
This leaves 30 kgs for frame, front forks, wheels, tires, brakes, fuel tank and everything else.
I don't think it's possible, especially if want it to look like a Vincent.
I got the weight down to 155 kg dry on the Egli but had to really struggle to get it there.
The biggest weight saving vs stock Vincent was in the front end and wheel.
A modern GSXR front fork and tubeless wheel is about 40 lbs lighter than the girdraulic with stock Vincent type wheel.
The monoshock rear frame and GSXR wheel knocked off another thirty pounds or so.
The Egli upper frame was good for another 10 pounds or so of weight saving. The alloy tank knocked off about 8 pounds vs steel stock.
The rest of the saving is in the stuff you don't put on the bike, same as with a racer.
When all done it's a lot of weight chopped, but of course there is no Vincent remaining in the rolling chassis.
Not much in the engine either, but it does have the approximate architecture of a Vincent engine, and the great bloody weight!
There is a bit of road equipment on the Egli, but it's not much, maybe 5 lbs, the lightest stuff I could find.
Magnesium cases would shave a further 12 -13 lbs off, but the durability there is a big question, especially for a race bike.
Andy Molnar felt that the Vincent cases done in magnesium would not stand up.
He said they have a hell of a time with the Mg Manx cases, and they are heavily webbed for strength.
So a lot depends on whether it is built using original Vincent parts or not.
Sure some lightening can be done here and there, but these are still quite heavy components by modern (racebike) standards.
Building things as light as possible is great fun, it does add a challenge.
The result is quite pronounced. 120 pounds removed is roughly equal to a 20 bhp gain and unlike with tuning, the performance gain is all across the rev range, plus there are the handling and braking benefits.
Glen