New magnesium Mk1 32mm Concentrics ex BSA Hailwood triple.

I have had these for 35 years, still in Amal boxes. Weigh less than half normal. Must be only pair left, no matter how deep your pockets. Might put them on the Covenant Commando but what are they worth?

I'd eBay them and retire on the enormous fortune.

only a pair of them,im sure mike would have had 3 on his bsa

chris plant said:

only a pair of them,im sure mike would have had 3 on his bsa

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I think in this context the pair = set.

I’m not at all familiar with the “Covenant Commando”. Is it an exotic ex racer, or your pet name for your road bike?

New Amal Premiers would be far better carbs for a road bike with their anodised slides, removable cleanable pilot jets and easy adjust stay up floats.

The weight saving from your magnesium bodied jobs wouldn’t even be noticeable on a road bike.

Unless the Covenant Commando is an exotic ex racer, I’d sell ‘em and buy some Premiers.

How much is a weight reduction of half of next to nothing ? However, might be worth bragging about, especially if Peter Williams' Commando racers had magnesium carbs.

Sadly, a pair means a pair. I bought them from someone well known in the Competition Department so I assumed they were connected with the magnesium/titanium 250 cc Motocross GP programme. There, every gramme counted for the only fourstroke in the Championship (the bikes handled well and were torquey but were too heavy and when super-lightened were too fragile). It was BSA’s last World Championship effort as I recall in any type of GP as opposed to Production racing

But when I called him thirty years later he could only think they were the last of the Hailwood cheat carbs where there were rules prohibiting some special parts and the Triples were heavy, even in Rob North frames. Hailwood was a rich guy so could have funded them.

Only a fool would think that any carb launched fifty years ago was as good as carbs half a century later, but only a similar fool would claim Bert Hopwood’s 70yr old Norton design was worth having a forum about when you can blow a Commando away with a DOHC multi half the size and ten times as durable. Functionality isn’t the point. History, rarity, curiosity and emotion are more relevant.

As for whether it’s worth saving a pound here or there, no its isn’t if you ride a fully dressed Interstate and live on donuts and french fries. Go read about Francis Beart or Alastair Laurie. Talk to aviation designers or even makers of bicycles. It’s no differeng to tuning except the saying wouldn’t be “How fast can you afford?” but how light. When you’ve countersunk, drilled and waisted every bolt head - even the alloy ones, when you’ve drilled every bracket and trimmed every cable, suddenly saving 600g per carb or whatever becomes a big deal to the obsessive. Sure, you could lose weight or hand the bike to a tiny rider but that’s not the point either...

Yet despite my own obsession at the time, I still added weight by modifying the timing cover to divert the oil from the pump outside the engine to an external full-flow cartridge filter in front of the engine and back through a second hose to the end-fed crank. Why bother improving oil filtration when running with open bellmouths? Good point - ‘because I can’?

As for Peter Williams, the JPS bikes used magnesium for the two largest single parts - the wheels. I used the same but cast in aluminium - which was about 4-5lbs per wheel more IIRC. Plus going tubeless would save more. Yet the Covenant Commando is about 310 lbs vs PW’s :350+? Don’t remember exactly. Anybody know? And I mean verified on a proper scale not a BS number?

PeterCrespin said:

Yet despite my own obsession at the time, I still added weight by modifying the timing cover to divert the oil from the pump outside the engine to an external full-flow cartridge filter in front of the engine and back through a second hose to the end-fed crank. Why bother improving oil filtration when running with open bellmouths? Good point - ‘because I can’?

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Sounds good to me, do you have any pictures of your modification please, an oil filter after the pump and before the bits it will protect, novel. (I have a spare timing cover)

Someone asked the other day, why go to all that trouble when you can buy cylinders with reduced (weaker imo) diameter lower spigots, why ? because I can, besides it doesn't always have to be a good idea or logical.

Look in the Covenant fork kit thread I started posting in a week or so ago. Someone posted a link with a load of photos.

Not sure how to upload one here. Image button won't let me browse my pix and I can't be bothered loading them onto photobucket first, or some such. If they have to come from somewhere other than my hard drive you'll have to PM me.

Try this link although no timing cover close up. Will take one in a day or two.

http://s566.photobucket.com/user/triumphsprintst0/slideshow/Norton unearthed

Whoa that’s a stunner...!

I think you’ve posted pics before haven’t you? I recall seeing that frame and swinging arm at least, which, I think is amazing.

Not sure why you didn’t tell us that the ‘Covenant Commando’ is such a beast, I did ask, and even googled it and came up with naught.

Could you tell us more about it, in a separate thread perhaps?

Anyway, back to your original question, scrub my waffle about Amal Premiers... a bike like that should DEFINITELY have the magnesium bodies carbs !

What is the biggest circulation classic magazine (or any magazine) for bikes? If I write it all up again 30-odd years after I wrote it all in British Bike Mechanics (Later 'Magazine') I want to do it properly.

Meanwhile, I just took this shot. Caption should explain all if it shows up. EDIT: seems not to show up so here is the key...

Top left of cover=new breather (needed due to dry primary drive? I forget).
Hex mid centre= magneto chain inspection (mag lighter than alternator & batt)
Mid right=new oil-tight cover (points chamber cut for 2xchain mag conversion).
Lower left=oil pump output diverted via quick-release feed to filter.
Lower center=full-flow filter oil return to engine/big ends.
Lower right=Guzzi cartridge on remote filter base in cool air.

PeterCrespin said:

What is the biggest circulation classic magazine (or any magazine) for bikes?

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I would guess ‘Classic Bike’ has the biggest circulation of the classic mags.

PeterCrespin said:

What is the biggest circulation classic magazine (or any magazine) for bikes? If I write it all up again 30-odd years after I wrote it all in British Bike Mechanics (Later 'Magazine') I want to do it properly.

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I'm biased, but here in the states there's only Motorcycle Classics that I know of. PM me for more info if you're interested and I'll get you a contact email.

Some years ago I was running magnesium carbs with methanol fuel. All was well until I omitted to remove the carbs after the last run and wash them in petrol. The methanol reduced the magnesium to a sponge like matrix, and the carbs were ruined.
Before attempting to run these carbs with our modern fuels, most all of which now contain ethanol in some percentage or other, it would be sensible to find out whether the ethanol will have the same disastrous effect