BSA B50mx 1973

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BSA B50mx 1973

Post by webby16 »

Hi all not the first b50 I've had experience with the the first 1 I've had running nicely and enjoyed riding!

Had a b50t which was restored back to a standard t spec, had a nice slim mx tank on it and the lozenge silencer was swaped to the mega rare later american marlet twin megas. It just wouldn't start nice and I blew up the gearbox when my motocross boot engaged the kickstart in a jump landing and then found the frame was cracked just below the engine cradle.
So ended up outing it.
The second was an mx project that never quite made it off the ground, it was made up of an engine and frame I picked up separately.

But the current B50 MX is a peach! Was imported from America it was clearly a flat track bike but whoever owned it had maintained it well. Although it did not look it. I was pretty bare, had universal guards on it, no panels and someone had very skillfully cut and shut an FMF motocross silencer onto it.
Screenshot_20220724-233308_eBay.jpg (21.62 KiB) Viewed 1524 times
After a good going though it runs really well, easy starter, idles and the front end is very light in first and second!
It has some great original parts, it has the late groves stanchions, mx air box, correct alloy based factory seat and the header pipe was orginal black chrome. The 1 into 2 silencers were kept in storage after the b50t was sold, so they once again returned onto a B50.

The engine was overhauled found it had megacam camshafts with the round foot followers, the head has been ported.
The bore was slightly on the limit so an 86mm piston was put in and electrex world ignition was used.
Put a PES outrigger plate on and alloy pressure plate, some magnetic sump plugs all round to give it an easy life.
Also had a British filter off of a B40WD hanging around for about 20 years and finally got to put it into use. Swapped the original b50 engine plates put for B25 rear engine mounts with the extra holes for the oil filter.
Nos side panels were sourced and fit ok... had to drill a hole for zip locks for use on the rough stuff.
NOS orginal stainless guards are on the bike also!
After a few laps on wet muddy track the biggest issue was the original footrest are awful!
So set about making a grippier set not to ruin the originality they were made from scratch the and old ones keep safe!
The heavy silencers were dropped also for a gp silencer and I had to repair the one side panel and the inner c frame section had come apart also! (Thank goodness for the zip locks)
This is how the bike looks now... i have also fitted slightly longer rear shocks to the standard ones.
It's such a great bike! Effortless, fast, smooth and it goes all day! I am no way competitive on it it's a lot faster than my capabilities!
Thanks David

CWM Speed :mrgreen: <212
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