Just asking for some help on which gearbox sprocket to use for the above.
I acquired this machine recently having been last used in 2019 with a view to making it safe and reliable to ride

My machine has been fitted with a sidecar gear, although as far as I’m informed by 2 previous owners it has never had a sidecar
Sidecar gear 17 tooth
Standard gear 21 tooth
A friend who owned one of these a long time ago made comment they were overgeared, and you had to rev the engine to make it go

Thanks in advance
Julian