Making a BSA lighter

[Lukey]

Hi all, the A10 is finished, just waiting for the MOT place to get a slot and its all good to go

So onto our next project

A BSA B33/ B31 cafe racer

It wont be to replicate a Goldstar ( using goldie tank etc) It will be built as a caferacer/road legal race bike for comfort, handling and most importantly lighter than normal

The plans are alloy tank ( may have to be fiberglass due to cost of alloys ones), alloy mudguards, alloy rims etc

The engine will be built by a friend who race's goldstars so will have lighted flywheels, goldie cams etc etc

So I am trying to sort out other ways to save weight

Will Alloy engine plates ( same thickness as the original plates) be up to the job??

What else couldnt I get away with lightening/ making out of alloy?

The frame, hubs and forks will obviously remain standard.

I was thinking -

Engine plates
Headlamp bracket's
Mudguard stays
Custom footrests
Speedo/rev counter mounts
Custom seat ( single seat either bought or made up, you guessed it out of alloy oe fiberglass )

Any idea's??

Many thanks

Luke

[lawnmowerman]

Hi Lukey

A fibreglass tank may be a bad idea with the increasing amount of ethanol in petrol nowadays. I don't think the new liners work with fibreglass.
Duralumin used to be the stuff for engine plates back in the day with loads of holes drilled in it and finished with swirls using the end of a small buffing wheel and metal polish. Not sure if Dural is still around or whether it has been replaced with something better - I am sure someone on the forum will know.
If you are going down the clip-on bars, headlamp brackets and rearsets route then you could also go for rubber gaiters and cut down the lower fork shrouds.
You will need to watch for vibration damage if you use alloy guard stays - they always used to snap off at the mounting holes after a while. Possibly stainless might be better.
Look foward to seeing pics of progress.

Jim

[chaterlea25]

HI Luke,
Another weight saver to consider is the clutch, BSA/Triumph ones are heavy
If you can get hold of a splined (plunger ) gearbox mainshaft, A Norton hubbed speedway clutch will save a few kilos
When time allows I have a project on using a dural sprocket and a Suzuki GS500 clutch (ebay less than £50)
this weighs about 2 kilos total (once the Suzi steel gear is removed)

Alloy wheel rims and using the crinkle rear and single sided front hubs will save considerable weight
The BSA full width rear wheel must be one of the heaviest wheels ever ???? ????

BSA B31 iron heads/ barrels weigh a ton

Good Luck
John O R

[mike667]

exercise and a wise diet are probably the best weight saving/reduction plan!

[muskrat]

Ha, Mike. That's what they used to say to me !!
Luke, most of what I have done has already been said. The '56/'57 Ariel hubs will shed a few Lb's.
Depends on how deep your pockets are, titanium or even alloy bolts. Duralium wherever possible eg brake stay arms, engine plates and brackets.
Cheers

[trickytree]

We had a nose around Dave Thorpes works 500 Honda motorcrosser at Hawkstone Park many years ago...that thing took weight saving to the extreem. Not only were bolts (most of the bike come to that) made from unobtainium but they were drilled down the center. The penny washers for the plastic guards had little hole drilled all around them and the frame had just one coat of red paint, you could see the steel when up close.

Daft thing was, it was sooo far under the minimum weight limit that they had add ballast to make it legal, reputedly a length of chain in the airbox!

[Rocket Racer]

I've always thought the best and cheapest way to reduce the race weight of a bike is for the rider to eat less pies and drink less...but it hasnt happened yet.
 

[beezalex]

IF you're really serious: Lightened flywheel, Belt primary, Fiberglass seat pan, fiberglass or alloy tank, alloy mudguards, Commando TLS or disc brake front end, any rear hub but BSA (Husquvarnas are nice and light and go on easy), Alloy rims of course, and, as has previously been mentioned: Don't reach for that last donut...

[fido]

I don't need a BSA lighter, I don't smoke. 

[A10Boy]

Ouch..... 

[tombeau]

 

[Lukey]

Okay people, thanks very much for all these idea's, the Diet is on the go at the moment, I lost a stone already  As for the bike, Im slowly collecting up the bits and pieces, got an STD gearbox, exhaust wrap ( may not use this) Modern rear sets although I may use others, oil tank although It may be worth trying to source an alloy one, alloy guards, lengths of stainless for the mudguard brackets Half a Crinkle hub for the back 

Havent decided on the exhaust as of yet, id really like an open race mega but I think it will be far to loud on the road, but we shall see  even if I have it for shows

Ive also been pricing up alloys rims and tyres ( modern for saftey and handling) 

All thats left to get so I can start building is an engine and a frame!

I have seen conversions for goldstar head and barrels onto a b33/b31 engine but I think Im getting into Mega Mega Bucks, something I dont have 

Ohh and I have thick ( and I mean thick lol) sheets of alloy and the engine plates drawn out on them, all I need to do it cut them out and drill a few weight saving holes in them

Havent decided whether I am going to use fairing, Id like the classic racer look but obviously it has to be road legal, I have an Idea of hiding a set of lights in the fairing at the front by cutting a hole in the front and mount two round lights in therem, but the cleaver part is that there would be an alloy race plate screwed over it so they cant be seen during the day, also same with the seat, mount the light and numberplate int he back of the seat so they dont stick out 

Im already getting rather exited about this project, we just need an engine and frame, ohh and forks 

[muskrat]

Some good ideas there Luke. Go for a reverse cone mega, a little quieter but a lot more tunable.
Now you got me thinking. I have a '51 plunger frame and a FZ1000 motor, might make a widowmaker.
Cheers

[Lukey]

haha, Ive also picked up a set of brand new goldtops, well my grandad had them in the loft, they just about fit me round the calfs, once ive slimmed down I may fit in them proper

Once Ive slimmed down, a full race leather suit will be bought, in the style of when it was raced, only thing I will use is a modern helmet as saftey comes first   I do have an original Pea pod, an original and a replica  

As for the widowmaker, I do ride sensibly on the road, Im the kinda guy who has no strings attached as im only 18, no wife, kids and morgage to pay, its been one of my dreams to own a goldstar but thats not going to happen in the near future, so I thought Ill build my own one instead to ride 

I also dont see the point in building a bike to original spec especially the racing bikes as I dont find them particually comfortable! It will be built for comfort ( if you ca have a comfortable racing bike  ) Im 6ft2 so it will be a tight squeeze to make it comfortable as there not particually big standard 

[muskrat]

I had to read past your 1st line. Down here goldtops are magic mushrooms. Couldn't ride after them