If you can make the engine go rich at full throttle, the fuel tubing is OK.

If not, you will need to go into the tank and change the aluminum tube and the interior fuel line to something larger and drill out the clunk.

Also, the Bisson HIGH VOLUME pitts for the MOKI 2.10 adds a couple of hundred RPM.

And finally, Zingers tend to load down the engine more than other brands.

Jim