What fuel do you use in your CBR?

It might be high peformance with respect to power for its size, and its rpm range, but its still an old engine, these engines were made for 91 Octane, infact afaik, 95 and 98 RON weren't even available when the 2fiddy engine came out in the 80's.

98 RON should only be used in engines that have a high compression. see here:

"Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where octane is raised by blending in ethanol, energy content per volume is reduced."

"Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause autoignition.

"It might seem odd that fuels with higher octane ratings are used in more powerful engines, since such fuels ignite less easily. However, an uncontrolled ignition is not desired in a spark ignition engine."

"Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power."


Basically, whatever the CBR Manual says to use, will give you the best performance, for those who say their bike runs shitty on 91 or 95, its probably because 98 is harder to burn, and likes to stay behind in a lower compression engine, can apparently clog shit up Ive heard.