MZ Saxon Sportstar 125cc - Determining BHP

[snuffpig]

Hello

I have an English MZ ETZ Saxon Sportstar 125cc (1997).

In the manual it lists two variants for this model: An "S" with 10 bhp and an "SX" with 15 bhp.

The manual makes clear that the S has a 24mm carb and the SX has a 26mm carb fitted. Another difference is the S has an EM 125 engine while the SX has an EM 125.1 engine.

Is there any obvious way for a novice like me to visually distinguish if my Sportstar is the S or SX?

[snuffpig]

I've just had a close look at the carb and it's a "Bing 53", which I believe is factory fitted.

Does anyone know if that's the 24mm or 26mm part?