Topic: spark arcing from plug booty to head.......

[stinkfinger]

77 CB750A.  #2 cylinder firing intermittently so I changed plug and low an behold.....
Its arcing across to the engine head from the rubber spark plug booty! (not touching)
Never seen that one before, anybody ever seen something like this?
Spark jumping from rubber/plastic to metal, whoda thunk it?!
I guess the coils are putting out enuff juice

Thanx
Tony

[Duke McDukiedook]

Happens all the time when boots are worn and don't insulate properly.

[dave500]

replace all the plug caps,the 2 plug fouled from weak spark from that cap,it cant get through so it sort of bursts out the side.

[stinkfinger]

Fixed, for now.... black electrical tape to the rescue!
She's purrin like a kitten again.
Will replace the caps..........thanx guys

Tony

[Deltarider]

Every SOHC four rider should make it a habit to check for sparks in the dark, every 3000 km or 6 months whatever comes first. It's often overlooked and people start taking their carbs apart and what not.

[fmctm1sw]

Every SOHC four rider should make it a habit to check for sparks in the dark, every 3000 km or 6 months whatever comes first. It's often overlooked and people start taking their carbs apart and what not.

+1.  I had THREE of the four arcing on one of my bikes...

[dave500]

carbs come apart more times than they need to,often over and again when the trouble is an easy fix elsewhere.

[tlbranth]

I noticed this phenomenon on my bike in the early 70's. A friend who was an electonic whiz told me that washing the bike and letting the water evaporate from the caps and wires leaves minerals on them which can conduct electricity. I believed him.

[Raul CB750K1]

I noticed this phenomenon on my bike in the early 70's. A friend who was an electonic whiz told me that washing the bike and letting the water evaporate from the caps and wires leaves minerals on them which can conduct electricity. I believed him.

Just the other day I saw arcing on boot #4 of my CB750. Never seen that before.

Coincidentially, I had pressure washed the bike the day before. Removed the boot and everything seemed fine -if only for a dull copper colour-, but then I took a day-long ride with no rough running whatsoever...

[dave500]

i blow mine dry around the carbs/fins and plugs with compressed air after a wash.

[Deltarider]

A friend who was an electonic whiz told me that washing the bike and letting the water evaporate from the caps and wires leaves minerals on them which can conduct electricity.

True.
I agree with Dave. Check your ignition electrics and check it again before you even think of suspecting the carbs.