Engine feels like it's dying at full throttle?

[Norris1977]

Hi I have a tuned 200 engine 30mm delorto and scootrs exhaust. Enginge starts first kick and runs fine up to just over half throttle after that it feels like it's dying back off the throttle and it's fine again any one got any ideas please?

[Andy Pickering]

Can you give us your carb set up please..pretty common set up I reckon.

[Norris1977]

Hi I'm not exactly sure as I'm new to all this all I know is that it has a 120 main jet.

[drunkmunkey6969]

Hi I'm not exactly sure as I'm new to all this all I know is that it has a 120 main jet.

Well, we are here to help....so if you dig into your carb and post the settings, we might have a fighting chance of suggesting a solution......other than that, we are not psychic.

[RICSPEED]

have you checked fuel flow from tank or fitted a fast flow tap???

[Andy Pickering]

Is this a recent problem ie, just come on after being fine or have you upgraded carb and exhaust and now have this problem..??????

[Knowledge]

The symptoms sound like classic under-size main jet. If the jet is too small, as the throttle readuces WOT (wide open throttle) the air flow increases but the main jet can't keep up. The mixture weakens and performance drops. Run it for too long like this, and you could have a siezure or a holey piston.

As changing the main jet is easy, try a 125 and see if things improve. If not, come back and report in.