Thanks for the welcome and rapid reply oldgitonabike. I should have been more descriptive,I have cleaned out the jets and all passageways ect the slide does raise when the Idle screw is wound in and will idle if you open the throttle slightly. Under no load it revs cleanly to full revs,however when riding it has no power from 1/4 to 3/4 throttle run rough (splutters and surges) but it clears up at full throttle and then it really flies. It is also consuming a slight amount of gearbox oil,I have replaced the crank seals however had to reuse the sleeve the seal runs on as they are no longer available from yamaha anymore. It has new bore piston and rings and starts easily it has got me stumped.