Intresting 920 racer - 290 lbs

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From the same source:
The fairing was a 1oz fibreglass lay-up, the seat unit and tank hand beaten from 16 gauge aluminium. The seat was just a single sheet of vinyl.
Home brewed brake discs were made at the local forge using scrap lo-ex car pistons.
Weight saving holes in the mudguards, bolts, spindles, clips, nuts, discs, the seat and the gears.
Just quoting :)
 
That’s all good stuff, that’d save some pounds for sure.

But 129kg is only 11kg heavier than a modern magnesium and T45 Molnar Manx!

Who knows who’s more accurate? But Mick Walker said the 1971 factory formula 750 Norths were 165.1kg dry.
 
Bragging rights are important for some people. If you have the best power to weight ratio, does that mean your motorcycle handles better or you can ride it faster ? Weight distribution has a major effect on handling. With most old bikes, it is normal to get the weight bias well forward. Otherwise they can be difficult and even scarey to ride fast in corners. Some people believe that neutral handling is better, but they might be wrong. If you watch that movie 'world's fastest Indian', Burt Munro added weight to get his bike to handle better. In his case, it did not work, but it is an answer to some problems.
Where the weight is in a motorcycle and the steering geometry dictate it's feel. If you get it equally light all over, it might be better. But aluninium barrels instead of cast iron make a significant difference. If you bike is extremely stable, you might not feel it. But most race bikes are on the limit of stability. If you get that light airey feeling in corners, you will usually back off.
A Commando is not a Japanese two-stroke. The torque characteristic makes it different.
 
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Fast Eddie said:
That’s all good stuff, that’d save some pounds for sure.

But 129kg is only 11kg heavier than a modern magnesium and T45 Molnar Manx!

Who knows who’s more accurate? But Mick Walker said the 1971 factory formula 750 Norths were 165.1kg dry.
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I suspect there are even more fibs about weight than bhp!

Glen
 
If you have the best power to weight ratio, does that mean your motorcycle handles better or you can ride it faster ?

Yes Al
 
worntorn said:
I suspect there are even more fibs about weight than bhp!

Glen
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creative accounting... taking numbers from one pocket (weight) and adding them to another (power)!

I agree though, and it still goes on today it seems.
 
I remember the blue T150 engined bike being lifted by its new German owner. MCN did an article. Alistair fitted a baffle to the open exhaust operated by a piano wire to a choke lever. Loved his bikes & still lust after one. At the time though I had just sold my T160 to put down as deposit on my first house with the misses.
 
For all we know the German owner may have snapped his thong lifting that bike!
We don't see the after picture of these lifters. Maybe they hobble off to the ER, prolapsed disc shoving on screaming nerves.
 
I remember when I was 21 lifting my T160 engine out of the frame & walking it over to the work bench.
About 10 years ago I fitted a T160 engine into a Rickman frame. I looked at it for a long time realising, knowing really, that I couldn't do it.
I then with that build had the rear wheel stand snap on my ramp & I struggled manfully holding the wheel against my thigh. Hand on the swinging arm trying to pull the frame towards me to keep the bike upright as I walked backwards & tried to get the wheel on the floor because the weight of that bike would have destroyed my garage itself & me if I had let go!
Currently building a P & M Kawasaki. The engine stayed on the floor & the frame went over it. It's still on the floor!
 
Two-strokes probably have the best power to weight ratio. But they seem to have come to the end of their road. In the 70s, they were a much easier way to go road racing. The problem with any race bike lies in finding a level playing field for it. If there were decent classes for two-strokes, I would still own my TZ350G. But I made a conscious choice and sold it to buy a decent gearbox for my Seeley. A good guy on an RS125 Honda would make it look stupid.
 
Chris said:
I remember when I was 21 lifting my T160 engine out of the frame & walking it over to the work bench.
About 10 years ago I fitted a T160 engine into a Rickman frame. I looked at it for a long time realising, knowing really, that I couldn't do it................
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I've a similar realization, in about '82-84"ish" I had a SOHC cb750f. I took that engine in & out of the frame many times. With the tank and everything off or disconnected I could lay over the top of it and lift it up and out bit by bit. Then pick it up and put it wherever. No way, no how today, that's for sure. Been getting weaker for about 8 years now, turned 58 this past summer, but my brain still thinks I'm like about 18.(tore two of my rotator cuff tendons in my right shoulder falling from a UH-60 Blackhawk maintenence stand). I have to force myself to throttle back. I'm getting to where I don't recognize the person looking back at me in the mirror.
 
cjandme said:
I've a similar realization, in about '82-84"ish" I had a SOHC cb750f. I took that engine in & out of the frame many times. With the tank and everything off or disconnected I could lay over the top of it and lift it up and out bit by bit. Then pick it up and put it wherever. No way, no how today, that's for sure. Been getting weaker for about 8 years now, turned 58 this past summer, but my brain still thinks I'm like about 18.(tore two of my rotator cuff tendons in my right shoulder falling from a UH-60 Blackhawk maintenence stand). I have to force myself to throttle back. I'm getting to where I don't recognize the person looking back at me in the mirror.
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I'm with you on that
I'm now 60 I've taken a few of those cb750 motors out and carried them
No way could I do it now
 
Fast Eddie said:
Kids go to the gym to ‘get ripped’.

I go to ‘keep the decay at bay’...
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Don't think I could handle a gym after a days work after lugging lengths of metal about
I'm struggling to lift a 92kg gas bottle onto the back of my welder these days!!
 
I'm really liking the idea of a lite weight 920...I remember a post to a thread about a p11 that Jim Comstock was building for a customer who lived out in west texas, ( iirc it was a 1007) but it also used a mag so no battery . Super light.... Super nice. These billet aluminum barrels that will be coming soon, look great towards going one step lighter too.
 
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My monoshock racer was 320 lbs with oil and 1/2 tank of gas (& heavy iron cylinders). That's as light as I could make it and still be stable with enough HP to compete with Ducs and Harleys in the mid 1980s. Check out the flat side on the points cover - thats from a 90 mph slide after hitting a pothole on the edge of the track.

Intresting 920 racer - 290 lbs
 
Fast Eddie said:
Kids go to the gym to ‘get ripped’.

I go to ‘keep the decay at bay’...
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I picked up a Kawasaki two-stroke motor, then went inside and sat down and had a stroke. Lifting something heavy uses a lot of oxygen.
 
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