You should use the lowest octane possible to prevent knock. You are going to LOSE some power if you use octane higher than is nessesary.
On super hot days and stuck in traffic my Bandit can ping a little(barely, I have to really crank it off the line) on 87 Octane. With 89 it doesn't. So I stick with 89 in the summer and then 87 in the winter. Simple. Putting in anything higher, say 90+, is a waste of money and power. THe octane rating is the combustability of the gasoline only, it's nothing to do with "power" or whatever. In fact you can make the arguement that LOWER octane has more "power" because its more volitile.
Always start out with the lowest octane and work up. It only pre-ignites on my bike when it's super hot and I've been stuck in traffic. If I were going on a trip with lots of highway and better cooling I could stick with 87 no problem. But since I'm in the city I use mid-grade in the summer.
The reason there is a myth about higher octane having more "power" is due to the fact that high octane fuel is used exclusively in high compression engines that have more power.
For example the Stock bandit compression ratio is 9.5 to 1. Some of the newer bikes have 11 to 1 or 11.5 to 1. So they can fit more fuel/air mixture into their cylinders per volume than our bandits, hence the individual firings of the cylinders have more power. However due to the fact that the compression ratio is so high you need a less volitile fuel so that the mixture doesn't pre-ignite robbing you of power and possibly damaging the engine. Hence the usage for high octane.
Most high compression engines are in sports cars/bikes rather than your mom's Ford station wagon so the un-educated will read their owners manual and it will say "Use high octane fuel of a minimum of 90 in this vehicle" and figure "well I must be getting more power out of the fuel because I drive this BMW".
Unfortunately for us, the fuel companies have picked up on the stupidity of some people and are charging more money for basically a tiny bit of additives added. It should only cost you about 5 cents a gallon more but the companies market the high octane as "V-power" or "Mid life crisis Super fuel" or whatever and charge you extra.
Topic: Sunoco Fuel (Read 6706 times)