Saturday 19 February 2011

BSA M20

I'd progressed from a Bantam to British twins. Like all young bikers I had absolutely no respect for these huge vibrating monsters, and happily spent many weekends and evenings bolting them back together. Still, a complete running bike was around £250 then, and as I worked in those days, it didn't seem to matter. Like many of my brothers I ended up unemployed, broke with a clapped out British twin, I swapped it for a Jag which I sold for £100 but, oh boy, I missed my bike. A friend of mine, had a friend who had a friend who had a BSA M20 500 single for sale quite cheaply.

I'd never heard of an M20 and was informed that it was an old sidevalve plodder - I dared not ask what a sidevalve was. The guy who owned it acquired a Harley and wanted £175 for it. He threw off the canvas cover and I was in love. I had to have it, even if it was 30 years old and clapped out. The big cylinder of that long stroke engine, and the basic brutality of the machine's appearance appealed. I didn't have the money right then, but a week later I had secured the funds.

It ran but not for long. It was taken apart, painted black and customised. Upon completion, it wouldn't start. I had to wait until Monday morning to buy the right jet for the carb, having bunged on an Amal 928 Concentric. This done, it started first kick and the carb really made a difference on its first run down to the South Coast. It was only supposed to do about 60mph but according to a friend on another bike and the wind in my face, it was doing about 75mph. I still don't quite know why.

My friend was nearly killed on that run; had he had the same lack of acceleration as I had on the M20 he would have been. I soon learned to adjust to this by planning ahead about five cars. I still do. A bad crash, the following year, 1983, totally wrecked my poor M20 (and me). Somehow I had to put it back together. With my body in plaster, finding the cash to do this was a nightmare but somehow I did it. £100 was the rebuild cost, including a new front end, carb, oil tank, seat and guards.

It's only now, seven years later, having had to buy virtually no replacement parts except points, exhaust valve and head gasket, that I'm doing a total rebuild. Have parts' prices gone up or what? £15 for an engine sprocket, I ask you? Still, that's the price of all this classic nonsense. On the good side, at least there's no shortage of parts if you can afford them. There are so many new parts still available, I can't ever see a shortage. For the desperate, there's an endless supply of used parts available at reasonable prices, although rigid frames are getting rare and tend to cost up to £75 wlb.

Luckily, I've got spare barrels, so I'll never need to bother with a rebore - just as well in North Scotland, the nearest rebore centre is 50 miles away. That kind of mileage, in this cold, god forsaken land, is a morning's journey on an M20. Oil consumption is fairly heavy so there's never any need for an oil change - I just keep putting more of the nasty, cheap stuff in. The M20 seems to love it. In emergencies, when the money supply is desperate, it often has to be used oil from the neighbour's tractor, but it doesn't seem to mind.

Fuel consumption isn't that special at 60mpg, but it's sufficient. A tankful seems to last the week. The new type of ozone friendly fuel doesn't seem to affect the beast, however, recently it has been pinking. I've put this down to the timing, opening the advance/retard lever to fully advanced seems to help slightly.

The clutch is a single spring type that is best left alone as it's a bastard to compress the spring. It's not really necessary to check the clutch, though I did, it really is indestructible and mine has never worn. I suppose it's to do with not needing to use the clutch as the bike pulls well in 4th at any speed from 15mph plus. I only use the clutch when starting off or for changing down through the box.

Changing down a couple of gears is almost as effective as the minimal drum brakes at slowing down the beast, but they don't have to be that hot as it's not a very fast machine. The gearbox is excellent. very simple, very efficient and very, very tough. Like the engine you can't abuse it enough. In fact, the only reason I changed the mainshaft was because I got a brand new one cheap and I felt I ought to buy the old girl something brand, spanking new.

Now we come to the first real fault - the gearbox oil seal. Absolute crap. I cured the massive leak with lots of red Hermatite and very thick tractor gearbox oil. Now it only leaks as bad as a seventies Bonnie. It's a pity I can't use Cornflake packets as an oil seal, although I did use lino as a sump plate gasket.

Need I tell you that the electrics are dismal. Not the magneto, that's never let me down, but the dynamo and regulator are something else. Not to mention 6V bulbs that blow - at midnight. We all know that all petrol stations don't stock 6V bulbs (actually, one near Exeter did) so spares in the tool roll are essential.

They're often broken too, due to the excessive M20's primary vibes, combined with the rigid frame's failure to soak up the bumps in our rotted road system. It would be nice to have some rear suspension, but it's something I've learnt to live without.

A 12V bulb in the rear often seems to save the 6V front, even if the lights aren't so bright. The rear actually becomes hardly visible so I rely on the offensive Maltese Cross lens for being seen. I will eventually blow £38 on a 12V conversion, as there is a lack of street lighting up in the wilds around here.

It's really the only bit of modernisation the bike needs, although it does seem outdated on the M25 when I'm down that way. I try to avoid motorways usually, so you can imagine how proud I was when I managed to get into the second lane on the M25 and overtook a Luton van. It's on bikes like mine that you appreciate agricultural machines on the road - it means you get to overtake something, if you can get past.

Unlike twins, I do find it strange that nuts and bolts stay done up, especially with the vibes I've already mentioned. One gets used to it and like a good woman, you really know you've ridden something. I can thoroughly recommend the BSA M20/21 to anyone who really likes unhurried touring. It's reliable to unknown extremes, cheap to run and needs virtually no maintenance. It has taken me all over Britain for next to nothing - to this day, my toolkit consists of two spanners (one adjustable), an exhaust valve, red Hermatite and odd bits of wire to repair my own wiring en route.

However, these machines are old as I've just realised. I'm 27 years old now and married, with that marriage came a great beast of a dog. So what? Well, I decided to fit a sidecar and the frame could take no more - it snapped right before my very eyes. It took some days to finally admit the 40 year old, accident bashed and battered frame might be better off without the extra strain, so it's now rewelded and solo again. Dog, wife? I've bought the German war counterpart, a Cossack 650 combo. A good alternative.

Anon.