Thanks for all the kind replys guys
here's a bit more about the govenor which i was a bit unsure about because my engine is a bit different to the plans, after a bit of thinking i dived in and came up with this solution. when i just had the govenor and no linkage connected i found when a certain speed was reached the balls flew out and stayed there untill the engine speed was quite slow and this seemed to make sence with the centrifugal force applied. But when i had added the linkage the weight of it made the action more progressive. The thottle valve is simple with a 1.4mm hole drilled thru a rod which is turned by the govenor link to misalign the holes, the pic shows how to go about setting it up while the engine runs, a small hole in the backnut shows the position of the valve and i have stuck a drill in there so i can see its position and lock it in suitable place. you can decide yourself when you want it to cutoff, it does work but the video i did was a bit shaky trying to hold the camera and play with the air control
Geoff