A lot of folks use lower than the recommended 90 octane fuel by preference and some places it's not even available.
If I hear a sound like clanking chains in 5th gear:
The engine is lugging badly. I'd shift quickly down into 4th gear.
To prevent pinging, one should bring up the engine speed before changing up in gear and drop to a lower gear anytime the bike will not maintain speed on grades or against the wind. Don't wait till pinging reaches the rattling stage before shifting down, you are then in detonation and courting major engine damage.
An octane booster may help some but keeping the engine rpms in the best operating range is critical to it's longevity. That's why all those gear changes are made available.
Lonnie
As Lonnie says, avoiding lugging is really important with any bike. With a sidecar, it's critical. As a general rule, I never let rpms go below 2,000 when underway, unless I'm on trailing throttle and slowing down.
That's on a Harley, of course and the minimum rpm would probably be different for other brands of bikes, although I recall my 1500 Gold Wing was about the same, although a lot smoother.
My Twin Cam is stock with 8.9:1 compression ratio and my truck and car are about the same. I know HD says to use 90+ octane but with ethanol making up 10% of the fuel we have, I can't tell the difference. For some reason none of my vehicles have any detonation, pinging, pre-ignition or whatever you want to call it. Guess I'm just lucky. LOL.
