i gotta 600fx , its sat over winter and i've put an acewell digi dash on.....
took it to snett and it wouldn't run prop..took the acewell off and its no diff....
i,ve changed the plugs cleaned the carbs & air filter...still the same.
it splutters at about 50ish and wont go any faster.... but it revs ok at standstill????? any ideas...

 

would taking the OE clocks off cause this..... its the only thing i did ..... it ran brilliant before...

 

That's odd, man. Sounds fuel related since it's under load. The FX is an F4, correct?
If so, I'd stop over in the F4 section and ask. Maybe they have some ideas.