Hello. Proud new B31 owner - Manuals Help

[Fraz]

Hi and thanks for having me on the forum.
Today, I collected my first British bike and even though it's got no battery, hasn't been started since 2016 so I've not heard it running and apparently there's no spark, I'm in love with the thing already.

She's a 1954 B31

Can anyone please tell me where I can download service manuals, parts lists, owners manuals etc?

Oh and what battery does it need please?

Many thanks

[Dan_B33]

Hi,
You can start here.
https://www.manualslib.com/manual/828471/Bsa-B31.html

If it has not been converted battery shall be optional for starting...you have magneto for spark generation

[Rog1]

Welcome! An owner's manual and a parts list are on the BSA Owners Club site, accessible if you are a member. The Haynes manual for the pre-unit singles is still available from the publishers. It seems to be inkjet printed now from a scan of an earlier edition; the quality of the photos is poor. It might be better to get a used one from Ebay.

I presume it's a swinging arm frame and magneto ignition. If so I don't know which battery will fit, but I have one of those yellow absorbed glass mat Motobatt brand batteries on my plunger frame M33; they hold their voltage for a long time which is handy on a bike that doesn't get used every week. Hard to say why there's no spark; do the relevant and usual checks for any points system and if you have no joy, ask again here. It may or not be the magneto.

There are also service sheets on the member's section of the BSAOC; handy for fault diagnosis.

[B44R Victor]

It may be a good idea to join the BSAOC now that you own a vintage BSA.  You'll have access to all of the Workshop Manuals on line and receive the Star magazine monthly.  In there you'll hopefully find contact details for a person well experienced in and having knowledge of your particular model.

[neil1964]

A B31 is a good place to start with vintage BSA.
Suggestions:
Replace spark plug with new one, replace the cap with non-resistor (non-suppressed)type and get solid copper core HT lead. You may find that you can get a spark of some sort like this.
Once you have gone over the contact points being clean and correct gap that is basic way to go before a potentially expensive magneto rebuild.
Battery is only needed for lights/horn but the regulator may need checking and hope dynamo is working.
Make sure petrol tank is clean and carb flushed through of any old petrol. Old motion lotion can be the cause of a lot of grief.
These tend to drain oil from the tank into the crankcase (wet-sump) if left for a long time, if the oil tank looks almost empty the oil will be in the crankcase (there is a drain plug to release it). Don't try and start until you have done this.
Familiarise yourself with the above (correct use of decompression lever/starting technique, how to encourage oil into the top end on start up - finger over the oil return tube just inside oil tank filler).
Lots of little subtle things (oiling cables, freeing up of stuck clutch plates etc) which make it all a little less daunting. Things that those of us familiar with such things do as matter of course.

[Fraz]

Welcome! An owner's manual and a parts list are on the BSA Owners Club site, accessible if you are a member. The Haynes manual for the pre-unit singles is still available from the publishers. It seems to be inkjet printed now from a scan of an earlier edition; the quality of the photos is poor. It might be better to get a used one from Ebay.

I presume it's a swinging arm frame and magneto ignition. If so I don't know which battery will fit, but I have one of those yellow absorbed glass mat Motobatt brand batteries on my plunger frame M33; they hold their voltage for a long time which is handy on a bike that doesn't get used every week. Hard to say why there's no spark; do the relevant and usual checks for any points system and if you have no joy, ask again here. It may or not be the magneto.

There are also service sheets on the member's section of the BSAOC; handy for fault diagnosis.

Thanks. I'll John the Club for sure.

It's a Plunger frame and to be honest, that's all I know about it (and old 4 strokes in general)
First job is to work out why the front brake keeps sticking on then releasing (after a backwards pull of the bike) and rolling free for 5 seconds before seizing on again.

Next, I'll run through the easy & obvious things to check for a spark and renew the lead, cap & plug.
Then I'll try to find the points - LOL

[Rog1]

Thanks. I'll John the Club for sure.

It's a Plunger frame and to be honest, that's all I know about it (and old 4 strokes in general)
First job is to work out why the front brake keeps sticking on then releasing (after a backwards pull of the bike) and rolling free for 5 seconds before seizing on again.

Next, I'll run through the easy & obvious things to check for a spark and renew the lead, cap & plug.
Then I'll try to find the points - LOL

You'll find that the front spindle has a left hand thread when you come to take the wheel out. My bike has a hard rubber box made to look like an old type battery, into which my actual battery fits. So if you have one of those measure the space inside and go for the biggest battery that will fit; probably of 6ah capacity.

When you find the magneto's points, (clue; look on the left side) they rotate clockwise, in the opposite direction from the engine.

[Fraz]

Thanks. I'll John the Club for sure.

It's a Plunger frame and to be honest, that's all I know about it (and old 4 strokes in general)
First job is to work out why the front brake keeps sticking on then releasing (after a backwards pull of the bike) and rolling free for 5 seconds before seizing on again.

Next, I'll run through the easy & obvious things to check for a spark and renew the lead, cap & plug.
Then I'll try to find the points - LOL

You'll find that the front spindle has a left hand thread when you come to take the wheel out. My bike has a hard rubber box made to look like an old type battery, into which my actual battery fits. So if you have one of those measure the space inside and go for the biggest battery that will fit; probably of 6ah capacity.

When you find the magneto's points, (clue; look on the left side) they rotate clockwise, in the opposite direction from the engine.

Thank you. All tips gratefully received.
Job for today - locate and clean points, clean pickup, new HT lead & plug.

[neil1964]

Points gap is 12thou and spark plug is a champion L82C with 18thou gap
Or NGK B6HS (don't get fooled into buying an R type as a weak mag will struggle)
Remember fresh E5 fuel!