is air filter ok, has fuel filter been changed, is it getting full throttle, is exhaust clear,is tank venting ok [is there a huge rush of air when fuel cap removed - there is normally a slight air rush ], check all fuel lines especially down back of engine -they rub through speedo cable/gearbox mount etc,check tank unit elbows for excess corrosion, there may be something in tank partially blocking outlet pipe? i would think timing is ok with you saying that it runs ok at times. [if there is a hand primer on filter head this could be faulty give it a good few pumps and see if it leaks,should go hard to press if ok]
k, January 2010
