What is detonation or pinging? - Harley Forum

ShortFatMexican · #1 03-13-2009, 08:48 PM

I remain confused to this day about what pinging/ detonation is or sounds like. I have an '09 FXDB w/ SERT, Stg 1 SE intake and V&H short staggered. 200 miles on it, just got it. What I sometimes hear is a sort of metallic sounding "chuffing" or "fluttering" sound when I accelerate from a stop up through 1st and 2nd gear. Thing is, it mad the same sound when it was new and stock. My '04 Fat Boy used to make the same sound. I'm hearing these sounds from the exhaust, NOT from the motor. I know from what I've read that detonation is the kiss of death. Can someone please explain?

Also this is my first EFI and does anyone have an opinion on the SERT? My Dealer was totally against a Power Commander. This is my first post and I welcome any and all comments. Thanks in advance.

shovelmike · #2 03-13-2009, 10:14 PM

Pinging/detonation is the condition in which the air-fuel mixture explodes rather than burning in a controlled fashion.
I saw an impressive demonstration by representatives of Champion Spark Plugs back when I was in automotive school in the early 70's. They dribbled high octane gasoline into a glass tube which was 2.5" diameter and 36" in length. When ignited there was a smooth flame travel from one end of the tube to the other accompanied by a low whistle. When the same thing was done using a very low octane gasoline the result was a very loud explosion that sounded like a M-80 going off in that shop.
When that explosion takes place inside a cylinder of a running engine it sounds like BB's being dropped on sheet metal.
It is a condition that has very destructive potential if allowed to continue.
I hope this clarifies it for you. Ride safe and God bless, Sincerely: Shovelmike.
And hey ShortFatMexican, welcome to the forum...and don't worry, I'm not getting and skinnier either...and definately not any taller either.

ShortFatMexican · #3 03-13-2009, 10:18 PM

Quote:

Originally Posted by shovelmike

Pinging/detonation is the condition in which the air-fuel mixture explodes rather than burning in a controlled fashion.
I saw an impressive demonstration by representatives of Champion Spark Plugs back when I was in automotive school in the early 70's. They dribbled high octane gasoline into a glass tube which was 2.5" diameter and 36" in length. When ignited there was a smooth flame travel from one end of the tube to the other accompanied by a low whistle. When the same thing was done using a very low octane gasoline the result was a very loud explosion that sounded like a M-80 going off in that shop.
When that explosion takes place inside a cylinder of a running engine it sounds like BB's being dropped on sheet metal.
It is a condition that has very destructive potential if allowed to continue.
I hope this clarifies it for you. Ride safe and God bless, Sincerely: Shovelmike.

So, you hear in the engine, not so much out of the exhaust, which is where I'm hearing it?

shovelmike · #4 03-13-2009, 10:25 PM

That's correct, you will hear it coming from the cylinder head area of the engine. I can't imagine what the sound is that you are hearing.

ShortFatMexican · #5 03-13-2009, 10:34 PM

Quote:

Originally Posted by shovelmike

That's correct, you will hear it coming from the cylinder head area of the engine. I can't imagine what the sound is that you are hearing.

Nor can I.... Oddly enough only my two Harleys have done this; I also have an '05 BMC Hooligan w/ 100" RevTech/ Mikuni HSR 42/ Samson Big Guns, and it never has made this sound. Also, I hear other bikes making the same sound all the time?! Like I said it kind sounds like a metallic "chuffing" or "fluttering" when accelerating. I know you're probably thinking "what the hell is this guy talking about?" Anyway, it doesn't sound like what you described and my '09 FXDB made the same sound when it was new. So I'm going to ride it like I stole it and not worry. Thanks alot for your help.

shovelmike · #6 03-13-2009, 10:39 PM

You are quite welcome. There are some really sharp minds on this forum, check back often and perhaps some of them will have some ideas.

unclepsycho · #7 03-13-2009, 10:39 PM

First off, welcome aboard....

I have a loose baffle in my muffler, and I guess it makes a sound like what you described. when I tap on the muffler it rattles too, thats how I know what my particular noise is..... maybe try tapping yours?? I have a 2 into 1 Kerker.

good luck

frisco-rigid · #8 03-14-2009, 03:40 AM

Hi SFM
I'm NOT one of those sharp minds that mike speaks of..

A well tuned "normal" motor like yours should virtually Never detonate on pump Hi-Test gas.. Plus,, I bet your motor has a Knock Sensor that should instantly stop detonation.. It'll feel kinda like a miss..
Very high compression & too aggressive Ignition timing will enable detonation..
Those are the 2 biggest reasons for extra High Octane gas..

When the fuel charge, with that low octane gas that Mike speaks of, ignites and burns too quickly, for whatever reason, too much pressure will be created while the piston is still rising in the cylinder.. That rising piston creates even more pressure (compression) & heat causing the rest of the charge to finish ignition waaay before the piston is at TDC.. A shock wave results,,, that is the Knock of detonation..
Look it up, you'll find a better explain I'm sure..

Pre-ignition is ignition Before the plug ignites the charge.. It's a symptom of a prob like carbon build-up for instance..
It can possiblely cause detonation by igniting the charge pre-maturely,,,, kinda like being advanced too much..
I've had to deal with and beat both at diff times..

Your noise.. Check what Unc spoke of..
Otherwise do this experiment for me..
While releasing the clutch when taking off from a stop give the motor a wee more throttle.. Yeah I know you'll accel faster so be careful,, see if it still does it then..

ShortFatMexican · #9 03-15-2009, 01:54 AM

If it ever quits raining I'll give that a shot. Thanks for all the info.

chipster · #10 03-16-2009, 04:13 AM

I'm also not one of those great minds mentioned before, but I'll share an my experience with a similar concern that you speak of.

I also had that same "chuffing" noise occuring on my '07 Wide Glide. Took it to the dealership and the technician rode it, experienced the concern, albeit slightly. The question was raised as to where my fuel was last purchased. When I informed them, they drained my tank, refilled with equal amount of gas, test drove, and within 25 miles or so the "chuffing" noise was gone. Never went back to that filling station again, never had the concern again.

May not be pertinent to your situation, but that's where my problem was.