Having had several BSA big singles as a youngster in the late 60's (even being a BSAOC branch treasurer for a while!) I am now thinking of getting one again. I have two questions which I hope someone may be able to help with:
1. What is spares availability like for a) M20 and b)B31/33?
2. Do you think they are usable in modern conditions?
If I needed "ordinary" spares (eg clutch plates, brake shoes, points) would I be able to get them within a week of so?
Lots of machines for sale are described as having been "in a collection".
Are they not ridden because it's not practical - ie maybe brakes aren't up to it or something?
Thanks for your help
(picture attached of my ex-WD M20 in about 1970. Don't suppose anyone knows where this actual machine is now do they?)
I ride 1964 C15.
Spares and parts are obtainable. Try ebay ,but there are several suppliers of new parts.
Mick
Hi, I ride a B44 trouble free and is very capable of keeping up with modern day traffic.
It has electronic ignition and is very reliable. Never had to buy spares for it but my other BSA's that i am rebuilding C11 1946 model i get parts from C and D autos , order Monday get them before Thursday.
Rob.
Thanks Mickreeves and Love British single cylinder.
Anybody got any comments on M20 or B31/33?
Brakes are the big issue, I've got a c12 and a b31 and am lucky to not have to contend with urban traffic, both are poor but even if they were at 100% efficiency they are not up to modern traffic without being lucky or extremely defensive
Evening Sarge,
I guess it depends on what type of riding you're planning. I use my old thumpers quite happily in rural areas where traffic is light and, if I find I'm causing a jam, I can pull over easily. I wouldn't use it on a fast, urban road though as modern car drivers are not used to encountering old plodders and I would feel the risk to both my safety and enjoyment too great.
Spares availability is good, particularly for engine parts. Some tinware is hard to source although Indian-made alternatives are available but quality and accuracy of reproduction are variable.
One of my bikes is an M21/B31 hybrid - the sporty B31 frame allows the 15 h.p. of the '49 M21 engine to really show what it can do :) :)
M20s are certainly increasing in value, especially the WD models. The others can still occasionally be found for reasonable prices especially as projects.
If you go for a unit single like the B40/44/50 then I think you'd be riding something a lot closer to a modest modern road bike in terms of performance and - hopefully - reliability.
Cheers,
Bernie
Thanks David & Bernie
I would mainly be riding country lanes, so hopefully will be OK.
M21/B33 hybrid is certainly the type of thing that would suit me!
(Don't want to go unit construction)
I have a swinging arm B31. It's fine for anything but do avoid motorways. In fact, if I have a long trip as in a few hundred miles, it's my bike of choice. There's something rather wonderful about blatting gently along at 50 mph enjoying the scenery. So much nicer than mixing it on a motorway on something faster and journey time isn't that much different.
Brakes aren't wonderful, but a bit of anticipation makes all the difference. One of my riding games is to see if I can complete a journey without stopping or using the brakes. Good practice riding for my clutchless 1913 Douglas!
I have a swinging arm B33 and use it on all roads except motorways. Keeps up with most traffic at up to 60mph; will go above that speed but it feels to cruel except for short bursts when overtaking. Like to go out for rides of 150 miles or so on country roads and over the North York Moors; tackles 1 in 4 hills OK both up and down.
Brakes are the problem with all the old bikes because modern cars can stop so quickly. I had the shoes relined by Saftek at Cleckheaton with their soft material, and use a front brake lever with a 7/8" pivot distance, and find the brakes quite reasonable as long as I remember to leave a good distance from the vehicle ahead.
Overall, I love a day out on it and ride as far as the seat allows, that's what I find to be the limiting factor on old bikes!
I'm encouraged that two different riders report trips of "150 miles" and/or "a few hundred miles"!
I ride a C15 SS.
I see no reason why these old bikes should not be very reliable, as they were 'in the day',
provided they are in good order to start with.
I ride it mostly flat out when out of the speed limit .(March town is only about a mile wide.)
No brakedowns yet, though I have lost the odd bit falling of. Silencer, Tool set, three times!
Mick
The brakes should be OK on an old bike.
My 1954 C15 has good brakes. I can easily lock the back wheel.
The front brake will get near to locking if I put in on hard. I would not do that in the wet.
Mick
Thanks for all the replies.
I have taken the plunge and bought a 1955 B31.
Coming tomorrow (snow permitting)
Exciting!
Well done! Is it a plunger model? And is it ready for the road or a project? Do post some pics when it arrives and let us know what you're planning for it.
I was hoping to get my newly built M21 combo on the road for the first time this week but, at the risk of being accused of being a fair-weather rider it's not great out there for learning to ride with an extra wheel!
Hope you have a lot of fun with it - guessing you're in UK?
Cheers,
Bernie
I find the M20 easy to ride and kick over. Can eb a bugger to start when warm but you will get the technigue. The gearbox does have more neutrals than most bikes! Brakes are fine for the speed you'll be doing. Convert to 12v and you can have good lighting and run other items (I'm just about to fit the wiring for sat nav and a usb charging point for phone.).
Just remember that top speed is 50 ish.
Spares are very readily availbale from several suppliers and NOS parts are still being found in large quantities!
Here it is!
1956 B31 Initially supplied to the Home Office and sent to Somerset Fire Brigade.
Only about 6k on the clock, which is possibly genuine.
Need some nice weather now!
Looks good, hope you enjoy many happy miles riding it.
Not by any stretch of the imagination would I describe a B31 as a "big single"
Well it's certainly a "single"!
How "big" does it have to be?
well there's a single ducati which was 600 cc then many at 500 cc and a few 440's etc a 350 is still a big single though as there are many more below . In my eyes a 125 or less is a small single . But everyone to their own .
A B31 is a big single. It's big and it's pre-unit. A B40 doesn't quite qualify. Anyway, this looks an excellent example and I would have room in my shed for it (except of course that my B31 would get jealous).
My one is a first kick starter every time, even if it has been languishing for months over the winter. What's funny it that after riding a faster more modern bike, for the first 10 miles you are wondering what you are doing riding this old thing then suddenly the magic happens. You relax, you get into the way of it and then the miles just pass. It's great for exploring the little roads that you would never normally bother with. And, as previously mentioned, great for the long trips too.
That'sa great looking B31 and I do love a B31. Interesting topic about whether this is a heavyweight bike. I've got a B31 but wouldn't have classed it as heavyweight, based on no information at all other than I only ever heard heavyweight in reference to 500cc and above, like M20/M21's. But in reality what's the difference between a swinging arm B33 and B31 except 150CC?
All the best,
Glenn
I would say anything over 650 is big,
Suzuki made a big single, the DR750 but that is tiny compared to this https://thekneeslider.com/nsu-2000cc-single-cylinder-motorcycle/
I think we need a new category of "enormous single" to accommodate the NSU!