Full throttle - LESS power

[spddm0n]

Hey all -

For some reason, when I take off from a complete stop, at full throttle, the scooter takes off fast!  While still at full throttle, and reaching about 20 MPH, it completely bogs down and struggles to keep going.  If I let off the throttle a little bit, it picks back up again.  ??  It still doesn't go that fast (I'm trying to learn how to derestrict it), but the fill throttle powerlessness is interesting to me.

A mechanic friend of mine said that the little valve, housing the fuel filter, appears to be acting on a vacuum line from the manifold.  At wide open throttle, when there is no vacuum in the manifold anymore, it would cause the fuel flow to slow into the carburetor.  Is this some kind of fuel flow safety switch/fuel restriction?

Thanks!

[spddm0n]

So, I just bypassed that valve (Kymco calls it an Auto Fuel Cock Assembly) and my scooter goes faster and maintains speed at full throttle!  WTF!?  How is the scooter supposed to maintain speed with this device in place?  I assume this device is to shut the fuel off while not driving, in the event the scooter is knocked over or something, correct?

[eamartin]

So, I just bypassed that valve (Kymco calls it an Auto Fuel Cock Assembly) and my scooter goes faster and maintains speed at full throttle!  WTF!?  How is the scooter supposed to maintain speed with this device in place?  I assume this device is to shut the fuel off while not driving, in the event the scooter is knocked over or something, correct?

Sounds like the valve is malfunctioning or the vacuum hose needs to be replaced.  You can replace the valve with an aftermarket item for cheap or bypass it and add a manual fuel shut-off valve in the fuel line down near the carb.