the cheapest thing you can do is try narrowing the point gap a little bit. i think stock is .016 if i recall, try .014.
the next most expensive thing is going to a bigger jet, the last time i tuned one of these I ended up with a 92 jet. if you have pulled the snorkel thing out, you might want to put that back in, the stock carb seems to prefer it.
tuning your variator also may help, you might be turning goofy high rpm's, in which case you are more likely to overheat. If you dont know what you are doing, you might be better off with a stock or notched variator to take one variable out of the equation.
tuning isn't a 'buy things and throw them at your bike till it works' proposition... its something with a methodology that you go through step by step. if you dont know what you're doing its best to eliminate as many variables as you can and work through things that could be causing the problem 1 by 1. More likely than not, your shaft seals are fine, you probably have an intake air leak, exhaust air leak, wrong timing, wrong jet, or something else free and simple.