We ran methanol in our racing go-karts with 5 HP Briggs. The modifications to burn it was that we had to drill out the carbs to allow more fuel, about double. There were obviously more modifications done, but they were mainly for power gains. As was stated, it is highly corrosive, and will corrode anything, including aluminum. The amount of fuel used caused considerable flooding of the oil, and very frequent oil changes with special, compatible oils. The whole fuel system and motor will need to be flushed after everytime it is run, and diaphrams replaced regularly.
Note that it has been about 2 years since we raced. We were paying about $3.50/ gal for the methanol. The oils we used ranged from $5.50 to $10.50 per quart.