You say you're a budget racer, I can understand that, been there done that. Still, I found the air density gauge to be very useful, if not essential. Air density and getting the right jet for the ambient conditions go hand-in-hand. People will tell you that these small engines don't respond to air density, trust me, they don't know what they're talking about. In my 50+ years in and around karting, I made a lot of mistakes, I did a few things right, and buying an air density gauge was one of the things I did right. Longacre, on the net, they sell the gauge, has some articles you might find interesting.
Just make sure you have every tool to take off and tighten every nut/bolt
Chain break, tire gauge, tire band (not a bucket), tire duro., Allen wrenches, screw driver/Phillips, snap ring pliers, socket for spark plug, zip ties, hammer
Extra nuts and bolts, wheel studs and wheel nuts, extra chain, batteries for tach
JUST HAVE FUN DOING IT...NOTHING WRONG BEING A BUDGET RACER
Channel lock , snap on , mac , klien. Otc , husky , craftsman , s-k .
Others im sure , nappa could have a good set , just gotta lookem over .
Piston circlips are the worst . Definatly need high quality there .