^^ but our engine does not have a knock sensor! Thus as the temps and loads increase, destructive knocking/pre-ignition/detonation can damage this engine. For those of you who tour in hot weather, added bags, added a passenger, AND added that 17th front sprocket, you are playing with fire running low octane fuel! Lower octane fuels "** CAN **" lead to destructive detonation when the circumstances stack up. Added carbon deposits from never revving the engine likely increase this tendency by another factor of 10!!!
My personal experience is this: I can hear mine knock on take off when temps are in the 85F and the engine temp is >195F. Granted that is rare but now add in this; When I take off going up hill its likely to detonate on 87 octane fuel. As someone mention, Running at sea level also increases the odds as do Dryer Climates. The air is less dense and offers less cooling in terms of cylinder filling. A cooler, denser air charge is less likely to cause detonation than hot air on a dry day. From this, I run Plus rated fuel 80% of the time. Any dry hot day I plan a ride, it gets Plus!
My bike has TB exhaust and stock gearing. I can't imagine I am the only one who has this happen and suspect many do not hear it happen! If its happening above 3.5K I doubt I could hear from all the F'ng noise the damn engine makes anyway as it has no noise damping properties. Its a race engine strapped between your legs!
FWIW: the ignition advance curve on the FZ is a fixed rate based upon RPM so it holds a linear vector increasing with RPM. It DOES NOT take into account engine load, gas quality, pinging, detonation, throttle position, gear selection, or anything tangible like a modern car does to asses calculated load imposed on the engine.
The fact that ignition timing control is fixed by RPM is a key ingredient limiting the FZ's hp output to 90+. At 14,000 RPM the resonant frequencies in the block would drive a conventional Pizzo electric knock sensor crazy as it would require very selective "electronic filter" to distinguish between knock of fuel detonation and reciprocating parts moving at crazy high velocities. Its likely why it doesn't have it as its a less expensive bike.
FWIW: I am attempting to procure knock sensor capable of ignoring the thrashing and listening for "detonation" so I can advance the timing and make more power. It must be! Also; our air box sucks as it takes the engines heat and traps it inside increasing the odds of detonation.
JJD952!
