RE: Bell 47 Crash
G'day Lawerence,who made the carby on your engine?,it sounds like you may have a partially blocked filter in the carby which will affect your engine regardless of throttle setting also did you get an operators manual for your engine as it will explain how to service your carby.
How's your fuel mix?,if petrol sits unused for awhile it will go off-still useable if you have a lawn mower tho' just doesn't let the engine run to reliably.
Has your engine done alot of work?, if so,it may need a new piston and rings and liner.Servicing both the carby and engine is fairly simple and easy to do,fitting the rings onto the piston is a pain tho' unless you can get the piston with them already fitted.
Hope you get it sorted,I never was in a position to get the early hirobo version of the B47,but Iam a proud owner of the mk2 version.
cheers,
Glenn.