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With the cooler weather, I'd like to experiment with different octanes (NO I AM NOT STARTING ANOTHER OCTANE THREAD). What does knock sound like? Frankly, I've been too busy worrying about idiot commuters to notice. And I'll stop wearing earplugs when I start experimenting.

Obviously, there are the names themselves- knocking, pinging, pinking. And I've read cagers describe it as 'marbles in a coffee can." I'll certainly check my plugs before and after. I've read some posters here that have had low-rpm knock in their Monsters; does that sound any different? Is there any surging/loss of power?

Also, my 620 keeps turning for almost a second after I kill the ignition- not much, but noticeably longer than in my cage. Does this qualify as run-on ("dieseling"), or is this normal? Might this be a "feature" of twins versus fours?
Rene Carlos
 

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I've never encountered run-on with my Monster, but then mine's an ie so that's nearly impossible :)

As for the "knock" sound, detonation and preignition both sound a lot like hitting a large piece of metal with a hammer. Halfway between "ding" and "thwack." Typically, at the onset of detonation, it'll be a little irregular (doesn't ping every revolution) and then as conditions get uglier in there (you press on, the piston and head get hotter, etc, etc), it'll become more regular and louder. Then if you press on, your engine will melt down some unspecified time after that... :)

I haven't encountered detonation on my Monster (a lot of people seem to think it's impossible with a stock 2V engine; I have no idea), but on my old air-cooled BMW (how different from the Monster could it be?) the sound is almost exactly like in a car, but a good bit louder - less stuff around the cylinder and head to absorb the noise.

In any case... Believe me, if you can hear AT ALL, you'll know the very second it starts. Pretty loud, and nothing like any of the normal noises the engine makes. On the BMW, I can hear it pinging, no problem, even when I'm wearing earplugs.

M.
 
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