Hi thanks haveing read what others say about the speed light, the speedo has a converter fitted, so 80 kmh becomes 80mph i think, also read on this site diaphram in petcock may be at fault so would starve the petrol supply, apreciate your views on this, muzz

Yes then it'll be 80mph,

You shoudl really be seeing around 120mph (where applicable of course).

Vaccum pipe is more likely than fuel diaphram.. when you have the throttle open hard the increased suction can cause the vaccum line to collapse and suck itself shut, which cuts off the fuel.

Is the airbox all standard?

Hi yes airbox is standard, will replace /check vac pipe. thanks, muzz