having engine failure speedfight scooter!!!?

I have a speedfight100cc scooter and recently whilst on the road at about 40mph it suddenly lost power and i let the revs down a bit and it picked up again and all was fine then yesterday it did it again but this time jus cut out and wouldn't start again, eventually it started through the kick start but again when i reach any speed over 30 mph it just looses power and just cuts out!!!! i checked the spark plug all fine and airfilter is clean i was thinking it cud be a dirty carb??? any ideas??? Thanks Mike.

Mike
April 2008