I did not find any way to adjust the lift on the piston. I think there are two possible solutions. One is to bend the lift rod down a little. I tried this and achieved some improvement. The lift rod metal and doesn't bent easily. Plus, the mechanism is fragile, so you can't really get a good grip on it. The second possible solution is to sand off about 1/32 of an inch off the piston top.
Just to restate the problem. The piston hits the bottom of the smoke unit when it is in the top position and creates the click and the hesitation. Therefore, we are trying to prevent it from hitting. I tried to shim up the smoke unit, but the engine boiler fits tightly over the smoke unit and will not seat in it's proper position with the shim in place.
