So, I've been tinkering, tweaking, and tuning my E50 Newport carb while waiting for clutch springs. I've just been trying to get it to run well stock before making any performance mods, And while I had been able to get it to run and accelerate smooth with a good idle, I was disappointed in the 24-25 max speed I could get out of it. I have verified that it is a 2hp model, with no intake or exhaust restrictions. Points, plug, Carb and exhaust squeaky clean, and timing is set. Piston, cylinder, rings, and compression all good, and running at its peak, I could still only get 24-25 out of it with my big ol butt on it.
So, in conversation with Ken Roff, he said to leave the stock air box off and see what happens. I did, and instantly gained a solid 5mph. That's a 20% gain instantly by ditching the demon vampire sucker box that was on there. So now I'm getting a solid 30mph and I haven't fine tuned my jetting or needle setting yet.
Moral of the story: Listen to Ken and ditch that air box, and replace it with a metal mesh filter and cut your side cover to fit.