Hi Rich,
I have sent you an email on the machines and also included the Gene Price.
The smallest Gene to run the G4 is a 12.5KvA - unfortunately these are very hard to come by now as the company who made them no longer trades. We have started to make our own due to this, Spec as follow:
15 KvA Petrol - Kohler Engine with a 2 Year Warranty - Alternator 1 Year Warranty - £2500.00 + vat
If you want any more info lease let me know