Introduced in 1988, the Yamaha Blaster is kind of the 5.0 Mustang of ATVs. Small, cheap, fairly powerful, light, simple and easily modified, the Blaster has become a darling among those looking for a good time without the pomp and pretense of more costly machines.
As it came from the factory, the Blaster used an "oil-injected" fuel system. That means that it had an oil tank to feed fuel into the gas mixture, negating the need for pre-mixing fuel. While filling up the oil tank every three or four rides is convenient, getting rid of the injection system is one of the first things most serious riders do. The pumps are said to fail without warning, and extreme angles and hard riding can slosh the oil in the tank, aerate it and starve the pump. Either way, the result is a disastrous lubrication failure, and a fried engine. Just to be safe and sure, many enthusiasts will install a pump block-off plate and run a pre-mix fuel.
The stock pump injects oil at about a 20-to-1 mixture, but most owners feel that's a bit excessive for this engine. Many enthusiasts who have installed a block-off plate like to run the standard 32-to-1 two-stroke gas-oil mixture; however, the power gains are minimal running the mixture that lean, and the engine will wear out more quickly. About 18- to 22-to-1 is a safe ratio range that won't cost you any real power. If you want to get the maximum performance and longevity out of your engine, use the highest octane, non-ethanol gasoline available and go with the factory-spec Yamalube 2R -- high-performance -- two-stroke oil used exclusively by Yamaha's factory race team.