Very Bad Timing - Embarrassing Mistake.

Peach

Peach

Joined
Nov 15, 2021
Messages
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Hello.
(Bike : '73 Commando 750)
I had a misfire due to corroded wires in the crimp-on connectors at the (Boyer) pick-ups.
Had to take the plate off to change the connectors - so I bought a shiny new strobe.
I was chatting at the time - probably showing off my new strobe - and I set the spark at exactly 31° (correct)
..... With my son maintaining RPM at 2000. (Very incorrect)
Yes - TWO thousand - I really don't know where my head was.
HERE'S THE WIERD BIT : (My phenomenal stupidity aside)
The bike worked fine. Gentle tickover. Plenty of guts. No pinking.

Only noticeable symptoms : a bit of kick-back on starting.
Did about 600 miles or so before, while pondering over this kick-back nuisance, I realised what I'd done.
Kicked myself harder than the bike kicked me.
Corrected now - I had the spark at over 45° btdc at full advance (estimated figure - well outside my markings on the alternator)
I'm a bit worried about the hidden damage I may have done.
QUESTIONS :
1) Why did it work okay with the spark so wildly advanced?
2) What damage should I expect?
 
Peach said:
Hello.
(Bike : '73 Commando 750)
I had a misfire due to corroded wires in the crimp-on connectors at the (Boyer) pick-ups.
Had to take the plate off to change the connectors - so I bought a shiny new strobe.
I was chatting at the time - probably showing off my new strobe - and I set the spark at exactly 31° (correct)
..... With my son maintaining RPM at 2000. (Very incorrect)
Yes - TWO thousand - I really don't know where my head was.
HERE'S THE WIERD BIT : (My phenomenal stupidity aside)
The bike worked fine. Gentle tickover. Plenty of guts. No pinking.

Only noticeable symptoms : a bit of kick-back on starting.
Did about 600 miles or so before, while pondering over this kick-back nuisance, I realised what I'd done.
Kicked myself harder than the bike kicked me.
Corrected now - I had the spark at over 45° btdc at full advance (estimated figure - well outside my markings on the alternator)
I'm a bit worried about the hidden damage I may have done.
QUESTIONS :
1) Why did it work okay with the spark so wildly advanced?
2) What damage should I expect?
Click to expand...
The advance range is about 12 degrees. Since you were at 2000 rpm when you set it, some of that range was used. Max, you were at 43, probably actually 38-40. That's a good bit over normal for a Norton, but not outlandish. If it wasn't knocking (pinking) or backfiring above 4000 rpm, then you hurt nothing. May have felt stronger than normal - within reason, more advance = more power.
 
You may have noticed higher engine temperature, perhaps more blue on the exhaust headers. As others have said, nothing to worry about.

Slick
 
Deckard said:
I wonder where the term for pre ignition evolved from pinging to pinking?
Click to expand...

Pinging (US) and pinking (UK) are terms used to describe detonation.

www.cycleworld.com

Confusing Detonation And Preignition

Preignition destroys immediately, detonation wears by degree. Knowing which wrecked your engine will give you a clue to what to fix.
www.cycleworld.com www.cycleworld.com

Detonation and Pre-Ignition

Detonation and Pre-Ignition Often confused and misunderstood, these two abnormal combustion phenomena are as different as night and day. by Mike Busch Although we often hear people describe what goes on inside the cylinders of an Otto-cycle engine as being an explosion – i.e., a violent...
resources.savvyaviation.com resources.savvyaviation.com
 
baz said:
Maybe a language barrier thing
I've never heard of "pinging" in the UK
Click to expand...
Have you heard of knocking in the UK?

Although you can find lots of Internet sources that say that pinging and knocking are different, you can also find lots that say they are the same. When I was young, we mostly said knocking instead of pinging, but the US is a big place, and I grew up in a military family so who knows if my experience was common.

So, to me, knocking = pinging = pinking. Pre-Ignition and Detonation are more descriptive, however many use detonation when they mean pre-ignition.
 
I'd Like to thank everyone for their various reactions.
I feel somewhat reassured by your replies and the bike seems fine.
I enjoyed how the thread went from my silly mistake to the etymology of slang words for pre-ignition.
My Dad always said "pinking" or "dieseling"
"Knocking" is when your mates come round for a beer.
 
Peach said:
I'd Like to thank everyone for their various reactions.
I feel somewhat reassured by your replies and the bike seems fine.
I enjoyed how the thread went from my silly mistake to the etymology of slang words for pre-ignition.
My Dad always said "pinking" or "dieseling"
"Knocking" is when your mates come round for a beer.
Click to expand...
:D:D:D See how this works - you brought "dieseling" into the conversation!
 
We always pronounced it with the "g" sound, pinging, after the sound of hitting an anvil with a hammer.

Course & vulgar lot we are.
 
Don't worry about embarrassing mistake. I have a friend with 50 plus years of experience. Many NZ club titles for his bikes.

Managed to time the bike after TDC not before. It did start but sounded as flat as a pancake. 🤣🤣🤣🤣🤣
 

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