ATC90'S WITH A ENGINE SERIAL NUMBER'S SMALLER THAN 1113934 OR ABOUT 1971 AND OLDER
I just wanted to give you a status update. I have about 250 miles on the 120cc kit, it's great fun.
If someone is in Denver or similar elevation and they want to use the stock carb with the altitude adjuster, the best settings are:
35 pilot jet
72 main jet
needle on middle shim
1.5 turns out on the air screw
I can get over 50mph on the flats and I'm 260lbs. Larger jets run too rich at my altitude and the engine's hot enough I wouldn't go leaner. I understand the 22mm carb will breathe easier but at my weight 50mph is spooky enough and I have other bikes for pure speed. The CT geometry seems happiest at 40mph and your kit's given it outstanding grunt for such a little bike.
Thanks again for creating such a cool kit for the bike!