Hello Everyone!
I've just joined this forum because I'm considering buying a B40, and need a bit of advice.
Let's get the hard bit done first... I'm a big fan of Triumph twins. I hope this admission doesn't result in me being cast into outer darkness!
However, I would really like to try a typical light/middle weight British single from the sixties, and the idea of a B40 appeals, as it's seemingly a fairly light machine with adequate power.
'Adequate for what?' you may ask. I would be planning to use it mainly for country lane and B road pottering, probably on local bike club ride outs where we seldom exceed 50-60mph. Brief dual carriageway excursions may be necessary, where I would need to be able to cruise at 60mph for 10 minutes or so, simply to keep up with the trucks and avoid being pushed along by said juggernauts.
I don't imagine a 250 would have the performance for this type of use, hence the 350cc B40 appears a better bet, with the added bonus that prices of these machines seem quite reasonable.
So my question is 'will a B40 have the performance and capability I'm looking for?' Or am I barking up the wrong tree?
Thank you in advance for your insights and experience.
Nigel
Not a bad plan. At the risk of offending some, I had a B40 many years ago and was glad to see the back of it, but the cycle parts are tough and it has a reasonable amount of power.
B40s come in various varieties - standard, SS90 tuned (mine was an SS90 and the thought of 90 on it is terrifying) and quite a lot of ex MOB ones with some different cycle parts and every colour so long as its NATO green.
I think the ex MOD ones are a good buy, they are often quite low mileage and sat around in warehouses then got sold off and sat around in sheds.
Personally I would not recommend the SS90, mine had the feel of a bike that would have been much nicer with less compression and softer cams.
Now I'm going to commit heresy as a lifetime BSA owner - take a look at the Matchless G3 / AJS 16, a lot of bike for your money. Very similar in performance and build to the B31 but about 60% the cost.
Hi,
A B40 will meet your needs. Once sorted they are reliable and because of the short wheelbase are ideal for country lane and A/B road twisties. Standard compression is about 6.5:1 so really quite a soft engine that can be bit nippy if given its head.
Dave.
Thank you gents, that's encouraging advice. I'm not looking for the peaky performance of a highly tuned/stressed engine like the SS90, and would prefer the gentler power delivery which the basic, low compression B40 appears to offer.
I'll let you know how my search goes. My ideal bike would be basically sound, but with a bit of potential to improve while still riding, a kind of rolling improvement project.
Nigel
I had one, a 1961 B40 (404 KYD, where are you now?) and like the post above, I too was glad to see the back of it.
I would recommend an earlier B31 if you want a BSA350. Better in every respect.
Yes, whereas I sold the B40 after a few months I kept my B31 for about 25 years! The B31 is a lot heavier and old fashioned but its smoother, more comfortable and has a magneto which I personally prefer for bikes used occasionally
Quote from: limeyrob on 14 Oct, 2026, 21:11 Yes, whereas I sold the B40 after a few months I kept my B31 for about 25 years! The B31 is a lot heavier and old fashioned but its smoother, more comfortable and has a magneto which I personally prefer for bikes used occasionally
I had a B31 back in the 1970s. Certainly a nice bike, but a bit heavier than I want now.
Nigel
Wouldn't think the B31 is noticeaebly or appreciably heavier though.
Quote from: V500 on 15 Oct, 2026, 16:57 Wouldn't think the B31 is noticeaebly or appreciably heavier though.
Food for thought, thank you. I just compared specications and the B40 is only 20lb lighter. Perhaps I should revisit my teens and get a B31!
Nigel
More readily available in a far wider range of choice, better made and (probably) greater spares availability.
The WD B40 was a good bike, but as for the earlier Civvie B40s....just think C15, but more so..
"..just think C15, but more so". Yes, many mates had C15s and when a B40 came up I thought it would be like a faster, better C15, and in a way it was, but it also had the C15 faults only more so.
I don't know about your budget, but a lot of Victor Specials seem to have arrived from the States recently and they do look fun.
I had a 1969 Victor Special briefly a few years ago. It looked like fun, and on a good day it could indeed be a fun ride. I eventually became tired of its unreliability.
To be fair, it turned out to have been poorly restored, and perhaps a good one would have offered more fun and less frustration. I sold it at a loss and moved on.
Nigel
Sorry to hear that, but you may have just saved me making the same mistake!
It seems to be everyone's immediate thought re those bigger BSA singles..."will it start?"
Quote from: limeyrob on 15 Oct, 2026, 21:09 Sorry to hear that, but you may have just saved me making the same mistake!
I don't believe all 441 Victors are bad. The one I bought was cosmetically good but a mechanical nightmare. Stuff would fail as fast as I could fix it,and I grew tired of fixing it when I could simply jump on my Triumph TR6R 650 and ride with no hassle.
Is just my experience of one particular bike, and I don't want to put you off.
Nigel
Quote from: V500 on 15 Oct, 2026, 21:30 It seems to be everyone's immediate thought re those bigger BSA singles..."will it start?"
I'm sure starting technique has been discussed on this forum. I had a procedure that would start the Victor Special from cold within three kicks most times.
Nigel
Here's a pic of my pesky Victor. It looked better than it rode!
Nigel
That is very nice, tempting......
Hi,
Interesting re the weight of the B40 and B31.
I have had two B40s and found them to be light and with a shortish wheel base, great on twisty lanes.
I always thought they weighed about 295lbs, as per the Instruction manual, which is not much more than the C15 at 275lbs from which they are derived.
The swinging arm frame B31 share pretty much the same rolling chassis as the A7, A10, Goldstar etc.
The B31 engine is not going to be much lighter than the twins if at all so not much saving.
Dave.
A B31 feels very much like a A7/A10 except to the power. The riding position is identical.
Quote from: limeyrob on 16 Oct, 2026, 22:17 A B31 feels very much like a A7/A10 except to the power. The riding position is identical.
Indeed. And aged 17, how I wished my B31 was an A10!
Nigel
So it's happened... Ebay showed me a nicely restored 1961 B40 just 30 miles from home. At the price when the auction finished, it would have been rude not to.
It's not been ridden much since restoration. A few test miles this afternoon show is all good but needs a little fettling, oiling cables, adjusting tickover, nothing major.
What it really needed is riding. I'm looking forward to that!
Nigel
That looks very nice, report back on how you get on with it.
Quote from: limeyrob on 20 Oct, 2026, 20:39 That looks very nice, report back on how you get on with it.
Thank you, will do!
Earlier in this thread, we discussed the weight of a B40, and I found data online showing a wet weight of 364 lbs, only 20 lbs lighter than a B31. This didn't feel right, the B40 gives the impression of being significantly lighter than it's predecessor.
I've roughly weighed my B40 this afternoon, but putting the front wheel followed by the rear wheel on old digital bathroom scales and adding the readings. I get a total of 305-310 lbs wet. This makes much more sense to me, it's a bit heavier than a C15, but not much.
The moral of this little story? Don't believe everything quoted online!
Nigel
The 1962 BSA factory data book gives the dry weight of the B40 as 295lbs.
Quote from: JulianS on 20 Oct, 2026, 21:47 The 1962 BSA factory data book gives the dry weight of the B40 as 295lbs.
Thanks Julian, that makes sense.
Nigel
I too have found bike weights on the web to be all over the place. Even the old manuals seem to disagree. A good idea to weigh it and settle the issue.
Hi,
Apart from the incorrect weights given by internet searches the anomalies in handbooks etc.may be caused by wether dry or kerb weight is used. Add a tank of fuel and some oil and about 30lbs may be added to the dry weight.
Dave.
Quote from: DAVE BRADY on 21 Oct, 2026, 09:46 Hi,
Apart from the incorrect weights given by internet searches the anomalies in handbooks etc.may be caused by wether dry or kerb weight is used. Add a tank of fuel and some oil and about 30lbs may be added to the dry weight.
Dave.
That's true, of course. When I weighed my B40 yesterday it was semi wet! Oil tank was up to the mark but petrol very low.
Nigel
Here are a few more pics of my new acquisition. It has been extensively and no doubt expensively restored, but ridden very little.
After a session riding then fettling then riding again, I'm very pleased with it. It's cosmetically beautiful and mechanically sound. It merely needs minor stuff like adjusting and oiling control cables, tightening the rear chain, tightening the steering head.... Quite a few little jobs that turn it from a pretty and shiny bike to a proper riding machine.
To say I'm pleased is an understatement. Thank you for your advice here when I was merely thinking abiut a B40, this forum is a great resource and a welcoming place!
Nigel
Hi,
If you are not already a member of the BSAOC then please consider joining. There are Branches all over the country.
Dave.
Quote from: DAVE BRADY on 22 Oct, 2026, 20:42 Hi,
If you are not already a member of the BSAOC then please consider joining. There are Branches all over the country.
Dave.
Yes, now I own a BSA, I will join the club 👍
Nigel
Quote from: DAVE BRADY on 22 Oct, 2026, 20:42 Hi,
If you are not already a member of the BSAOC then please consider joining. There are Branches all over the country.
Dave.
None in Scotland.
Hi,
Well it just so happens that an embryonic branch is developing in Scotland.
Contact Andrew Solomon, email andrew.solomon751@gmail.com
Dave