Dear friends,
does anybody knows which is the max official speed of a BSA M20? Thanks a lot Devis

email (option): devis.vadori@gmail.com

112 MPH BSA M20

As well as being painstakingly restored by enthusiasts to accurate wartime specification, the M20 has also been developed by specialists for speed trials. A 1938 BSA M20 ridden by Bill Jenkins from Dallas achieved a top speed of 108 mph at Bonneville Salt Flats making it the fastest M20 for this venue in the world. The original side-valve engine was extensively modified and fuelled with nitrous oxide. The intake port fed by the carburetor, originally horizontal, was re-drilled at a steep angle into the cylinder casting so it pointed up at the underside of the intake valve. The motorcycle did however retain the long BSA prop stand that hinged under the seat and clipped to the rear mudguard when not in use — so it looked like a stock M20. In October 1995 an M20 fitted with a BSA Gold Star crankshaft sprocket and running on a 95% methanol / 5% acetone mix ridden by Pat Jeal achieved a terminal speed of 112 mph at the disused airfield of RAF Elvington, Yorkshire.

https://en.wikipedia.org/wiki/BSA_M20

Wikipedia


If I remember correctly,
The factory top speed according to BSA WM20 specs is 102Km/h 64Mph

Noam.

email (option): noam10@gmail.com

Thanks Noam, but what I need is the speed of a "regular" model WD M20. I am helping a friend to obtain the historical certification for his M20, and the Italian department needs to know also that details. Thank you again for your info, nice to know that our M20 could be so fast !!!

email (option): devis.vadori@gmail.com

Hi Devis,

I was just editing by answer when you replied..

If I remember correctly,
The factory top speed according to BSA WM20 specs is 102Km/h 64Mph

Cheers,
Noam.

email (option): noam10@gmail.com

Thank you very much, grazie 1000. Devis

email (option): devis.vadori@gmail.com

58-62mph was the 'off the production line target' that I read in some BSA literature a few years back......

Faster than a speeding bullet.. ...Ian

email (option): ian@wright52.plus.com

Ian Wright

Faster than a speeding bullet.. ...Ian

email (option): ronpier@talk21.com

Blimey, over 60m.p.h!!!! I don't feel brave enough to take mine over 45 yet!! I think all my fillings would come out 😂
Good luck, steve

email (option): S.johnson658@btinternet .com

I reckon they would hit 65 ? I took mine on my first open road run on the weekend, took it up to 55 for a bit and still had some to go, but found as you travelled it seemed to enjoy 50... sounded sweet and you didn't have to hang on for grim death

I find that 45mph feels a lot like 145...but I'm getting old and the bike ain't getting any younger either.

Bits definitely fall off quicker above 45.

email (option): sacombsashtrees@hotmail.com

My speedo doesn't work well, so I asked my son to follow me on his Aprilia.
He told me my speed was at about 88 km/h (55 mph?).
Another speedo that doesn't work?

email (option): drossi54@hotmail.it

Speedos on modern bikes get their data from the ECU which normally increases the displayed speed by 8% over the actual speed.

On the beach near Cherbourg I got up to just over 70mph on my oversize M20...but I have to admit it was beginning to lose its sense of direction on the sand at that speed...

Ron Pier clocked it at 75 or so along the sea front at Omaha beach but I've never tried to go faster than that...I couldn't stop thinking what a broken conrod would do at that speed... ....Ian

email (option): ian@wright52.plus.com

Is the con-rod much weaker then the one in a B33 engine.

Maybe or maybe not weaker but it is 7/8" longer than the 'long' B31/33 conrod...and I know how easily the M20/21 rod flexes when out of the engine..

Not only that, I had to ride the bike home from France!.. ..

I've got a Carrillo rod for my sprinter so I won't be worrying about that one...!

email (option): ian@wright52.plus.com

You've made a nice job of the flywheel Ian.

55 mph on motoways ok on mine....any faster with panniers and camping equip start to get into tank slappers and brown trousers!

65MPH tonight std engine but with 86mm W6 piston carefully rebuilt & 22 tooth engine sprocket.. nothing fell off!! but Ian,s words of snapped conrod flashed thru my mind....Dave

I read somewhere that terminal velocity from 30,000 feet was about 109 mph.

email (option): btcoop77069@aol.com