BSA engine number info

Hi all,

I have a BSA engine, which I believe to be a 420cc (From the length of the exhaust flame trap). I have a pdf of the original manua for the 320 and 420cc versions - which seems to indicate the engine numbers would begin with 'A' or 'E'........but mine appears to be: G 22283/PL/AS! There is also an 'HS' stamped above this on the casing.
Any ideas as to whether this confirms or denies the engine size?!
I've managed to re-establish a spark from the magneto - now need to check the carb and then see if it will fire up!!
TIA! Dave.

Not sure about the G, but Villiers tend tend to use HS to denote a High Speed engine which runs a bit faster than a standard engine to give a higher power output.

Before working on the carb just put a few drops of fuel down the plug hole and give it a pull to see if it fires

Thanks Stuart - interesting!
It was sold as a 320cc engine - but it seems to be potentially getting bigger/more potent all the time!!

Will give your suggestion a shot re firing!

Dave.

BSA 420cc HS (high speed) model. G = 5.75hp @ 3000 rpm
Lucky to have the original exhaust silencer.

Brilliant - thanks Blue cat!

Hi Dave.

I have manual for 320/420. PM me if you would like a copy.