Good to see you ole man, you on the lamb?Step 1 = blueprinting does help.
Step 2 = cranking compression pressure is important, check it often. A "good" compression gauge is not cheap, buy a good one.
Step 3 = check to see if the clutch is holding the engine at peak torque on the starts. Really important!!
Step 4 = exhaust gas temperature gauge (EGT) is a "real" tuning helper.
Two karts, side-by-side, going straight, hit the gas at the same time and, one pulls away from the other, can mean several things.
Two of the most obvious are, lack of horse power and/or poor clutch performance. If there's no "gearing" rule, I'd be looking at that too!
You might think that paying to get your engine tested on a dyno is expensive, but, just starting out and testing at the track for all the things you need to test for can be expensive too!
Tuning is tough" (Al Nunley)