Re: what is going to break next?
all the main things to watch out for have been addressed already, and since this thread turned into the old 4stroke vs. 2stroke debate, i figure i'd add something here.
i went to the deathrace with a bag of tools and no spare parts, and a modified 2 stroke HT engine with 8-10,000 miles on it.
the only time i got my tools out was to remove the supertrapp tip from my exhaust to make it wide open, and to get a screwdriver to pop the visor off my helmet.
beat the living daylights outta that motor, and it still runs great.
these are the simplest motors to learn on, to maintain, and to tinker with. once you figure it out, and replace the crap that was designed to fail, you really can't beat it.
i'm not saying 2's rule and 4's suck, i just don't think they deserve the bad rep some people give them.