Comet torque converter(TC) clones are cheap on Ebay and we are lured by the low, low price. I wanted to try for Comet performance at the Clone price, but you have to spend money to be broke. The big issue for the Clone is the springs in it are not a known value, we don't know at what rpm they make the clutch engage, we don't know how they respond to belt tension to increase the gear ratio. So I put genuine Comet springs in my clone.
I have noticed nearly everyone discusses the torsion spring, that is the one in the driven pulley. It is the easy one to adjust because you can just change the hole the spring sits in. The problem is that people are adjusting this spring to make the Kart(or minibike) faster. That is not the purpose of this spring. This spring controls the rate of gear ratio increase and decrease. These torque converters are also CVTs, continuously variable transmissions. They have a gear range from 3:1 to 1:1(It varies but this is the average), starting in the low gear and increasing as the engine rpm increases. You can adjust this spring to make the TC increase and decrease the change in ratio faster or slower. If you have a play kart that sees a lot of mixed riding on trails, you want it to change gears up slower and drop gears faster. If you are drag racing, you want to torque converter to increase gear as fast as the engine can handle it. If the kart has less power you may still need a slower gear ratio increase because the engine can't take the load otherwise. If you have a powerful machine, you only need the low gear to get off the line, then increase as fast as possible to get to the highest speed as fast as possible.
Talked about less often but just as important are the springs in the driving pulley. These are the springs that engage the clutch and you can change them, and the weights, to get engagement at the rpm that works best for you. Completely stock Kart? You probably need engagement at 2000-2500 rpm. Drag motor that spins 9000 rpm, has a huge cam, and doesn't make power til 4000 rpm? You need a spring that engages around 3800-4200 rpm. Between springs and weights, you can set the driving pulley/clutch up to suit your needs. NOTE: If you have a big block(420) or a MONSTER motor, the Comet 30(real or clone) is not the one to use. You are going to need a beefier TC like the Comet 500 or 700 series.