it appears as though it is not receiving petrol/when I press the bulb to fill with fuel at start/the line from the petrol has very little fuel passing through/ I have replaced spark plug

Ray Jones, December 2011

Try inspecting the fuel filter which you will find inside the fuel tank connected to the intake line, use a peice of wire with a bent end to hook it and pull it out to expose it, disconnect it and blow it clean with compressed air, failing this, replace the filter. Possible carby blockage may be also the cause. Try cleaning out your tank and use only fresh fuel.

dan, December 2011