This was a fantastic genuine barn stored bike which has been in the family for a generation. 1 of 2 bikes brought to us with the intention of restoring them both to an A1 concourse standard. We spent some time to get the bike running before stripping down to ensure the engine was of good condition before the full rebuild - This way we can can go into the rebuild knowing there's a particular area we have to look in on. 

Obviously this meant rebuilding/partially cleaning the distributor and points, hooking up a temporary working coil and plug - Test tank full of slightly oiled petrol and away we went.

Of course we spent some time to strip down the bike, being careful to keep, record and store each and every nut and bolt in case we choose to re-use them by renovating/plating in-house.

With the bike all stripped be begin the massive task of preparing every element for paint. Tin-ware and frame are sandblasted to remove the rust and paint in its entirety. We then move onto panel repair, body filler and primer.

Particularly, the rear mudguard required some work. there were two areas that were extremely thin upon return from media blasting... We decided to cut these sections out and butt in brand new steel - and braise them in flush. We choose to braise such repairs to try and reduce the amount of heat we put into the panel itself. 

After repairing panels in such a way - We will then test fit the panel and fix up tight! 


We then cover the blasted steelwork in a high quality rust inhibiting grey primer, ready for more work.


All dents prior to primer beaten out to reduce them amount of body filler used... then rust pitting is filled with a thinner aluminium based filler. Before the final coat of primer.

Once the paintwork is resting in its 2K Red. We move onto to rebuild the engine and gearbox. Once the engine was stripped, each component is meticulously inspected, cleaned and renovated ready for its imminent rebuild. The aluminium cases sent off to be aqua peened whilst we have a few things on order - every single bearing and seal... along with a replacement lay-shaft bush which we pressed into place and reamed to tolerance.

Bearings and seals pressed in, gear clusters dropped into place and halves put together with a fresh gasket and non setting sealant. 


From here, the rest of the engine is put together with close attention to aesthetic appeal for when it's  put back into the frame. Of course... valve timing set, Valves lapped and ground. The barrel exterior painted with VHT, honed and ring gaps checked before the piston is slid through.

With the frame and tin-ware in full paint and the engine fully rebuilt its ready for the final assembly where we can concentrate on the final components of the B40.  The wiring loom stripped, cleaned, tested and re-loomed in cloth as per original - UPVC where necessary around the engine. 

Wheels fully rebuilt with Stainless Rol-tru Rims, laced and balanced with stainless butted swaged spokes. The refinished hubs hold new bearings and seals, replacement speedometer drive, brake drum and sprocket unit and re-lined brakes front and rear. 


It has been an absolute pleasure working with yet another BSA - the engineering... although challenging at times, gives a great sense of achievement when the photography finally comes through.

BSA B40 Before

Image 1 of 17

BSA B40 After

Image 1 of 23