Author Topic: Most useful mods on a B40 Mk1?  (Read 351 times)

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Most useful mods on a B40 Mk1?
« on: 31 March, 2020, 10:56:20 »
Fairly new to this model, I'd like some advice on what to improve. It will mainly be used for less than a 100 miles trips at moderate speeds on asphalt and gravel roads, sometimes forest paths. When I got it, it already had alloy mudguards, a small seat, high level exhaust and a Boyer ignition. Since then I've replaced most of the electrical system. Fitted a modern regulator/rectifier. Added a capacitor so now it starts without battery. I've made a new battery tray for a slightly smaller battery. Relocated it to the left side to be able to adjust idling on the Monobloc without having to remove the battery first. Now weighting 132 kg dry. I think a decent weight.
It has a bellmouth with gauze now. I think I will add a sock foam filter. Uses them on the Honda classic racer and the Vincent with no need to change jetting.
A fuel filter might be a good idea as I'm not certain about the inside of the tank
The external oil filter fitted to military bikes is missing, so I think a Commando type filter will fit where the battery was before. Is there any smaller oil filter you recommend?
Are there any magnetic sump and gearbox drain plugs that I shall fit? Any improvement for draining the crankcase?
Maybe I'll add something for bringing snacks and tools with me.
Maybe add a skid plate like the one I have on the Victor.
What else do you recommend?
« Last Edit: 31 March, 2020, 11:44:30 by Mike40M »


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Re: Most useful mods on a B40 Mk1?
« Reply #1 on: 31 March, 2020, 11:54:52 »
Hi, this forum lark is all very new to me, hope it all goes down well, which is more than can be said for my BSA C11G, most is coming on well, till I started with electrics, it had no lighting/ign switch, I purchased new from montys classic motorcycles, wired it all up according to diagram in BSA service sheet -reproduction off eBay, as the bike is not yet running I have put a test on first of all light connections, but very little response position 2, no side light, no rear light, position 3 headlight, great a start, but then when switched back to position 2 headlight stays on, I intended to get all lights working first before attempting ign & charging circuit, but this is now beyond my diy skills & afraid will need some expert advice, if anyone out there is available & willing. any help would be greatly appreciated. not yet a member but I will be joining when this pandemic allows. best regards sandancer.


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Re: Most useful mods on a B40 Mk1?
« Reply #2 on: 31 March, 2020, 15:40:53 »

Perhaps the best place for B40 tips are the books by Rupert Ratio.  Some members of the forum are probably better qualified to comment as I do not actually have a copy so await their input.



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Re: Most useful mods on a B40 Mk1?
« Reply #3 on: 31 March, 2020, 16:04:32 »
Dave, aka Rupert is the goto source of all B40 knowledge, Ive only got the engine book and it is worth every penny. I had to call him for information and very helpful. probably tried all mods to a B40 ever tried.
my interest in B40's comes from my old unit landlord , his started first kick, went on VMCC rides of many miles with twins and bigger single keeping up.
youngest son has bought one as a project and trying to replicate, Boyer ignition and remote filter.