hello i have sold my old s2 rst and now just bought a s1 rst but i have a problem sometimes it will start but it will only run for 5sec then it will just die on me even if i hold it on the revs i hav looked at all hoses changed spark plugs leads dizzy. there is a good spark. on the metering unit if i take any of the red hoses off and turn it over is the ment to be petrol coming through coz theres not also when i undo the feed in pipe it piss's out of there is that right can any one help please