Thanks grumpy for the welcome. Wow! what a great easy to understand explanation thank you. No gravel or mud here just wet vegetation. I don't think the motor was changing speed and fuel consumption is a little less (I guess) than one litre per hour at 2/3 throttle on flat land. The inline clutches you mentioned, are located at the front of the engine? I' ll go and check for belt slippage now. Thanks once again. Phil
