Explain it to me

[Guest 000]

Sorry, nothing to do with boats.

I mowed my lawn today, during which the on/off knob fell of the mower and I ran over it.

So no way to normally stop the mower.

The only thing to do was flip the HT lead of the sparkplug with a screwdriver which I did and....nothing! The engine just kept roaring away, no change in revs, nothing. Checked carefully and there was positively no connection between the HT lead and the plug. Using the screwdriver shaft as a short between the plug tip and the mower body shut it down, but seems unusual?

[erice 732]

seem to remember if you have glowing carbon deposits in the head 

 

ignition may continue

 

old mower?

 

but then shorting the plug worked......

 

2 stroke?

 

old plug?

 

https://answers.yahoo.com/question/index?qid=20100710055344AAuSU7i

[wheels 543]

Wow that is weird Chris. Erice would be spot on if it weren't for the fact you shut it down by placing the Screw driver shaft on the Plug tip and shut it down. That is just plain strange. Unless it was just plain coincidence that the instance you touched the plug, the carbon deposit fell off or something.

[John B 106]

Semi diesel.

[Dambo 44]

Eric is right - carbon build up - old cars/plugs with significant build up (I remember my little Dashund and before that Triumph) would run on - even if the timing was spot on (which can also cause an engine to run on).  

 

Related: I had a little Suzuki GN250 that we did various modification on for fun - we did some careful skimming and swapping of conrod, retarding timing etc - we managed to up to compression significantly and turned it into a semi diesel - little bugger would chug and had to be run out of fuel to kill it.  Needless to say like most of them, we eventually chewed out the big-end bearing resulting in a demolition job while running flat-tack down the back of Whenuapai airfield - good times 

[wheels 543]

Early Escorts were another. But in saying that, they ran ruff as, because the timing was way out and as Dambo states, he had to replace the big ends eventually.
But this does not explain ChrisC's situation. Why when he shorted the spark plug out, did the engine stop? Explain that one.

[John B 106]

 Every  plastic/ whatever coated  HT lead I've taken off something crusty and ancient has developed a memory. You take the lead off and let it go and it sproings back and sits 1/2 an inch or so away from whence it came.

 

Arc.

[Guest 000]

Been down to the Big City (Tauranga) today.

Home now, and I'm going to see if I can replicate the issue.

[erice 732]

gremlin

 

probablly got bored

 

jumped to neighbors electrics

 

just to make sure

 

wave the leads of the multimeter in the shape of the cross above the mower

 

muttering ohm's law, V=IR

 

electrical gremlins don't like that and will often flee

 

 

if it's a mechanical gremlin

 

you'll need a hammer

 

for a powerful mechanical gremlin you might need a really BIG hammer to 'tap him out'

 

that'll do it

 

but sometimes, to spite you, they'll wreck whatever on the way out

[DrWatson 381]

Thank you, Erice, I needed a good chuckle.

Being homeless in the northern hemisphere winter doesn't seem quite so bad now ????