Multi-point EFI: Should I Use 92 or 95 Octane?

[BenjaminRose]

Whether to use 92 or 95 octane gasoline for multi-point electronic fuel injection depends on the motorcycle's manual and the engine's compression ratio. Differences in composition: 92-octane gasoline consists of approximately 92% isooctane and 8% n-heptane, while 95-octane gasoline contains about 95% isooctane and 5% n-heptane. Isooctane has better anti-knock properties, whereas n-heptane has poorer anti-knock performance. Therefore, the higher the octane rating, the better the gasoline's anti-knock properties. Each engine undergoes comprehensive evaluation before leaving the factory, and based on performance characteristics, the required anti-knock level is determined, specifying which octane rating should be used. Differences in power: Higher-octane 95 gasoline is suitable for engines with higher compression ratios. As these engines increase in speed, the ignition timing advances. When the speed reaches a critical point, the air-fuel mixture may ignite prematurely before the spark plug fires, a phenomenon known as "knocking." Increasing the gasoline's octane rating effectively enhances its anti-knock performance.