The Walbro WT-499 carb is made for your size engine, and alcohol use. With that carb you could run straight methanol, available at speed shops and go kart racing outlets, mixed of course with oil.
This would give a nice power boost.
Also, what is your setup? If you are using a stock muffler, stock carb, and/or have a worn ring, you can pick up a lot of power, (a lot!) right there.... Going from magneto to CDI ignition also provides a boost, as you can optimize the ignition timing. Then there are porting mods, pinning the piston and using a special ring which lets you grind the bridge out of the exhaust port, etc.
See here:
http://www.rcuniverse.com/forum/m_26...tm.htm#2621860
Been racing all kinds of things for years, and the first rule is, "Never hop up a worn engine; make it fresh first, and then do your hop up mods." I have had engines that ran well, but picked up 800 rpms with just a new ring....
AV8TOR