Bike Weights and Weighing

greg brillus

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Shaving weight off a bike like a racer is not too difficult, the wheels are the biggest problem. If alloy castings were replaced in magnesium the weight savings would be significant.......look at the wight of a Manx. Glen is right about the weight specs on the engine, and a belt primary/clutch is a huge weight saving........On the suspension you can save big amounts by doing away with all the spring boxes and shocks, with a single coilover front and rear that weigh in at 1 kg each.
 

Pushrod Twin

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Lose 20Kg, chop the gearbox off! Oops, sorry, that's culturally insensitive these days o_O But is it really? None of us would chop a genuine set of period cases these days, obviously, but is there a problem chopping a new, aftermarket pair? Do I recall that Ian Hamilton was discussing having new cases cast without the gearbox end and making provision for an AMC or similar box? I also understand that may be pushing the definition of the racing rules in which you are competing Vibrac.
Here's mine at 80kG, no zorts as quoted by Glenliman, but an alternator to make up for it. The drive side looks "standard" Vincent.
 

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timetraveller

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I see that you are using the same alternator that I have been fitting recently for the 'Walkernator'. I drive it at double engine speed on twins to ensure that it starts to charge at low revs. I also use a multi vee belt drive to take out some of the shock loads which are inherent to the standard Vincent dynamo drive. I could not mount my system as low as yours because of the standard gearbox top and yours looks very neat, Once you have it on the road I will be interested to learn about its performance with regards to shock loading the primary drive and low speed charging cut in speed.
 

Albervin

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It all depends where the weight is. I have ridden bikes that differ by less than 25kg and yet they feel 100kg different. I would love to lose some unsprung weight from my Shadow as it would make for a much sweeter steering and handling machine. I have thought about fitting Brampton forks as per my Rapide with coil over damper but that doesn't address the unsprung weight. Unfortunately Aussie roads are not kind to alloy rims so it is about the brake drums and sprockets.
 

oexing

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As to alu rims , are you sure about less sturdy than steel rims ? I imagine most off-roaders have alu rims, no steel . You have to hit a big stone right on to ding the alu rim but same with steel I guess. In that rare case you´d change the rim anyway so I´d prefer to have flanged alu and live with it. What matters a lot is a perfect job with spoke tensions all round for good rigidity of a wheel.

Vic
 

Vincent Brake

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It all depends where the weight is. I have ridden bikes that differ by less than 25kg and yet they feel 100kg different. I would love to lose some unsprung weight from my Shadow as it would make for a much sweeter steering and handling machine. I have thought about fitting Brampton forks as per my Rapide with coil over damper but that doesn't address the unsprung weight. Unfortunately Aussie roads are not kind to alloy rims so it is about the brake drums and sprockets.
Get the motorcycle center of gravity in the line from middle steeringhead races and other point is rear axle.

Tony Foale.
Yamaha.
And the rest.

And i can do you some heavily drilled drums
 

Monkeypants

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All of the things I was weighing on the bathroom scale suddenly got a lot heavier when I purchased a 700 lb hanging scale and 90 lb Postal scale.
On careful checking, it turned out that the bathroom scale was reading way low.
The hanging scale shows a standard 998 Vincent engine at right around 220 lbs with everything attached, carbs, exhaust, the works.
Other than the belt drive, I cannot see a good way to reduce the weight of the engine very much. It takes a lot of drilled holes to equal 1 lb. You could turn it to Swiss cheese and only take off a pound or two.
Chopping the cases would cut some weight, but you must add in some engine plate weight to get some kind of gearbox back on there.

The AMC trans is quite light, but it struggles to contend with the torque of a stock 850 Norton.

Do they hold up against a modified Vincent 1000 ?
Definitely wouldn't last behind a tuned 1300+

Maybe a 6k$ TTI would.
I think the 5 speed Quaife with its 200 HP gears in the Vincent cases is the best solution, although the end result isn't light.
 

Monkeypants

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It all depends where the weight is. I have ridden bikes that differ by less than 25kg and yet they feel 100kg different. I would love to lose some unsprung weight from my Shadow as it would make for a much sweeter steering and handling machine. I have thought about fitting Brampton forks as per my Rapide with coil over damper but that doesn't address the unsprung weight. Unfortunately Aussie roads are not kind to alloy rims so it is about the brake drums and sprockets.

Not much weight saving with Aluminium rims. 1lb per wheel going from chrome over steel Dunlop to Morad flanged alloys.
Buchanan Sun rims are heavier, they weigh virtually the same as stock chrome/steel rims. They are very strong though.

I haven't weighed them, but have read in mph that Bramptons and Girdraulics are almost the same weight. This was a surprise, the Bramptons look much lighter than Girdraulics.

Glen
 
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