| i sugest you remove the fuel tank and wash it out, inspect fuel line or better still replace both fuel line and fuel filter, make sure the line is a good fit to all connecting points, clean out carby once again paying attention to the jet or jets and needle / seat. also do you think your engine sounds louder when it does run, if so there is a chance there is a leaking crankcase oil seal, the stock seals and bearings are not good, its also a good idea to replace these with nsk brand. give these a go. | 
