Pinging?

[Ghis_imp]

Have our CBs been known for pinging? I'm hearing what sounds like pinging, when accelerating right off the throttle, in any gear, but not quite like the pinging I'm used to from my Harley days. Read somewhere here about fuel injectors noise. Do they sound like that? Is it just load on the valve train? It's not overly loud or anything, but I'm curious.

[the Ferret]

Yes, the injectors make noise very similar to pinging.

[flynrider]

It's more of a clicking sound that you'll most likely hear under hard acceleration at lower speeds (before the wind noise blocks it out). I was concerned about it when I originally got my '13, as I'd never had a fuel injected bike before. I even upped the fuel octane for a tank, just to be sure it wasn't actual detonation. It wasn't.

Coincidentally, I had my first experience with actual detonation on the CB11 a few weeks ago. I filled up with regular grade in a town that was at 7,000 ft. At those altitudes, regular grade is 85 octane. Two points lower than typical regular near sea level. When I rode from there to Phoenix (about 1,200 ft elevation) I got definite pinging when I goosed the throttle on the freeway. It was immediately recognizable and definitely a different sound than the FI clicking sound. I quickly made my way to the nearest gas station and mixed what was left of the 85 octane with some 91 octane premium. Problem solved.

[Pterodactyl_imp]

That's interesting Flynrider, I wouldn't have thought that altitude change would trigger that. I guess I have been enlightened. As for pinging noises, my high frequency hearing is so shot I'm not in the race to hear pinging. I just try to avoid lugging the engine and hope it's not pinging. Detonation is another description more often used in aviation than auto I guess. When I was a lad pinking was the usual term, sometimes spark knock. As opposed to bearing knock of course.

Cheers

[flynrider]

It wasn't so much the altitude change as the octane. Motor fuel sold in higher elevations has a lower octane rating (here in the Western U.S.). With less power being generated at high alitudes, an engine that uses regular grade 87 octane at sea level will do just fine with 85 octane at 7,000 ft. The problem arises when you ride down to lower elevations with that 85 octane fuel. To add to the problem, heat will exacerbate the problem and it was about 110F (43.33C) when I rolled into Phoenix.

I prefer the term detonation because it describes the premature explosion of the air/fuel mixture, commonly due excessive pressure and temperature on the compression stroke. It's different in origin (and often confused with) pre-ignition, which will cause the same ping/knock/plink noise, but is caused by a hot spot somewhere in the cylinder. Octane will fix the former, but not the latter.