The following is an overview of the YS 91SR engine.
Thanks to several people on this one:
Midland Helicopters and Robbe UK for supplying the engine, Trev Burley for allowing us to strip and rebuild his engine.
The following is a complete strip down of the YS 91SR engine and carb.
The following is a rebuild of the YS 91SR engine and carb after having been stripped down.