peugeot Elystar lack in power?

i bought this bike after ait was sat in a yard for over a year covered up and no keys. its a 53 plate 125cc carb not injection, Engine runs fine on tick over but when riding it seems to hold back, lack power and can't get more than 40mph out of it? i've replaed CDI and key unit,spark plug,petrol and air cleaner. aslo striped and cleaned carb and checks valve clearances on tapets. when riding it the red light for imobilizer is very faintly on and the more power i give it the brighter the light becomes. i only notice the light because i was working on it as the day light started to fade. it doesn't smoke or anything and i'm now lost as what to try next???