Hitchcocks Forum

A well know topic on this forum is the fact that the single engines including the Electra X 'eat' plugs. I carry a few spares in the tool bag. My bike just conk out and I found it to have a non functioning plug. Replaced it is all working again. Has anyone found out why this happens or ideas why?

Something as simple as flooding the engine is sometimes all that's needed to contaminate the porcelain surrounding the centre electrode.

This allows the spark to track along the contaminant down to the plug body to earth instead of the jumping the gap to earth electrode and producing a spark.

In defence of the humble spark plug let us consider its operational task. At 3000rpm it is expected to produce a spark at a rate of 25 times per second. It has to do this while dealing with a huge HT voltage, a massive heat range, a changing fuel/air mixture ratio and a compression ratio in excess of 6to1. Some demand on a piece of kit that at £2.80 costs less than a cup of coffee, a pint of beer (I live up north in Manchester),or a lunch time butty from Gregs! Change the poor thing more often, don't bother cleaning it and keep 2 or 3 brand new ones in your pocket or tool kit. When one finally cries enough any competent motorcyclist shoul be able to fit a new one in less than 5 minutes. Problem solved.

Fit an Iridium plug, costs more, but should last a lot longer. I had one in the Bullet; the plug was in there for nearly 20000kms, only changed it because it was a bit on the cold side and starting to soot-up. The makers recommend to not adjust the gap and not to clean.

Apart from the occasional, ordinary plug in the race bikes, or newly rebuilt bikes, I seldom change spark plugs in my machines, as I have not seen the need. When I do, I use the plain old ordinary types in them, too. My Tiger Cub has a very rusty looking plug which has been in there for well over 20 years and I can't remember changing any plugs in my Bullets, none of which use anything more fancy than points in their distributors and magnetos. Admittedly, the mileages I do these days on any one machine are pretty low and batteries and tyre pressures are a bigger concern to me. There are, however, new 'duff' plugs around and they are no good at all.

I concur with BW, I very seldom have a problem with plugs. If they get flooded or fouled, clean them off and they're good to go.
Having said that, I struggled a couple of weeks ago to find a fault with a Honda stationary engine - having tried just about everything I changed the plug even though it was showing a good spark and away it went.

I had an Electra for 5 years and thought "I'll fit one of those iridium plugs because I like spending money", fitted it and within days it had failed - put in original and it was there for the remainder of the time I had the bike.

Iridium plug every 5 years just for the hell of it..

Cheap NGK's are just that, some work and some fail out of the box..

Champion are still good if you can find one, and don't let the bike tick over for hours from startup...

Iridium plug every 5 years just for the hell of it..

Cheap NGK's are just that, some work and some fail out of the box..

Champion are still good if you can find one, and don't let the bike tick over for hours from startup...

Sorry not enough coffee yet..