First of all welcome to the forum.
First of all welcome to the forum!
Several things come to mind, but I'll keep this short. If you didn't install a new "window" piston or alter your old one with a piston window, the reed valve and new carb won't actually help performance and I would uninstall and put the kit carb back on the motor.Trying to get the new carb working at this time is a waste of effort. New valve reeds are initially quite stiff & require some break in time to start to flex properly and this sometimes makes carb setup a moving target that's hard to hit. Idle speed included. You may actually have an air leak as well with the new kit setup, especially at the point of engine to reed valve sealing. If you did put in a piston window or alter the "jug" with a third port then carb setup will be time well spent.
Let us know what you have exactly in addition to the Keihin carb. Post a photo of the reed valve and carb mounted on the engine. There are a few different brands/designs of reed valves Zeta, Gas Bikes, RSE types & some sell a couple of different versions of reed valves. Photo is best.
The people that sell the reed valves are either not honest or are uneducated in their claims about bolt on performance gains with reed valve,never mentioning the futility of installing them without one or both of the motor alteration that are absolutely required to make them function properly and the final fine tuning once everything is in place.
Best of luck.
Rick C..