500 (Classic) Engine Identification

Hello,
My name is John & have just become a member so Hi All & a Happier New Year to you all.
I have recently purchased a 1968 500 Classic with a spare engine & gearbox, can anyone tell me the quickest way to identify the difference between a 500, 600 & 650 Engine please.

Regards
John

The easiest way is to look at the engine number. There is a machined surface to the rear of the engine, just by the fuel-pump. A 500's engine number will start with "110", the small (594cc) 126 engine will start with "126A" and the large 126 engine (652cc) will start with "126A1". There are a small number of visual differences, the main one being the location of the starter. If the starter is at the top (at the back of the engine) it is a 500 engine---if the starter is to the side of the engine, it is one of the 126 variants.

p.s. Welcome to the Forum John, we are here to help you---feel free to ask.

Many thanks

Regards
John