Zuma "Flat Spot" By wpdupont (Read 840 times)

[wpdupont]

I need help fine tuning the set up in my 2005 Zuma. The previous owner installed a 70cc kit and a afermarket carb. I am not sure if any upgrades have been made to the transmission.
The problem I am having is that moped runs "flat" between 15 mph and 25 mph. Off the line the moped pulls strong, but once I get to about 15 mph the performance flattens out until I get up around 25 mph. Once I get past 25 mph, the engine pulls strong again up past 40 mph.
I need advice on where to start to eliminate this problem. Do I need to make adjustments to the carb, or do I need to change clutch springs/roller weights.
Any assistance you can provide would be appreciated.

[alleyoop]

Sounds like it is running a little rich at that point. What kind of carb is on there?
CVK carb or Slider Carb(throttle cable goes into the top of the carb). What needs to be done is to Lean it out in that range but to do that the needle has to get moved DOWN 1 notch.
Alleyoop

[wpdupont]

Carb is slider type (throttle cable goes into top of carb.) I will try moving the needle and respond with result.
Thanks for the advice.