Could use some info on this piston that I found inside one of my cylinder.

Has Heplex and 7519 written inside.

It is short with concave hollowed top.

On a Dranganfly page of 2008 7519 lists for M21 BSA.

Is this a BSA piston or is it another equivalent company?

Thanks for your help.

email (option): unpob@yahoo.com

That second number, 413, suggests to me that this is a Hepworth piston for a Royal Enfield but I'm not sure what Enfield it would fit. I think the number next to it (1716) is the actual piston identifying number. I could be completely wrong of course! Is it 85mm?
REgards, Mark

I don't have any number info...However, the dished top and lack of valve cutouts are features of the M21 piston...
An accurate gudgeon pin centerline to crown height would help to confirm it...(the gudgeon pins are 3/4"O.D. )...Ian

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

Thanks for the input, Mark and Ian,

Gudgeon pin is indeed 3/4" inches

Center of it to crown seems 1 3/16" inches

OD of piston is 82mm

Saw in a website listing that Heplex was an aftermarket outfitter

Am convinced enough that it is a WM21 600cc piston

Up for debate of course, nothing set in stone.

Here is a photo of the cylinder it was in.

Sitting for past ten years. How time flies

email (option): unpob@yahoo.com

Hi henri its listed as 82mm 1938/40 m21 comp 1.7/32" length 2.3/4" 2×rings@ 1.5mm 1@ 5/32" pin size 3/4"× 2.7/8" I have many reference books thanks mal

email (option): malmotorcycles@gmail.com

Cool Mal!

Thanks for the specifics