Outboard Sparkplug cap

[Ecosse120]

I own a Tomos 4hp outboard and last year the sparkplug cap broke, now this is an old engine so spares are a no no. The current cap had a screw that went into the lead and was then held onto the sparkplug with a spring. Does anybody know were to get a replacement or can I just change the end fitting ? Any help much appreciated.

 

[VicS]

I own a Tomos 4hp outboard and last year the sparkplug cap broke, now this is an old engine so spares are a no no. The current cap had a screw that went into the lead and was then held onto the sparkplug with a spring. Does anybody know were to get a replacement or can I just change the end fitting ? Any help much appreciated.

Just fit a modern cap, without a resistor, of your choice .

It's presumably a 14mm plug ?

Plugs come with a "bullet" screwed onto the terminal. Some caps fit on to the bullet, some will fit the terminal without the bullet.

The insulator of 18mm plugs, like those in Seagulls, is a larger diameter

 

[Ecosse120]

Thanks Vic, I believe it is a 14mm plug, how do the modern caps fit to the lead, will it still be a screw or will I need to solder it on ?

 

[VicS]

Thanks Vic, I believe it is a 14mm plug, how do the modern caps fit to the lead, will it still be a screw or will I need to solder it on ?

Different ways. May be with a screw that goes down the centre of the wire. They are most likely to be hard plastic caps. Simple to fit. Just screw it on.

My outboard plug caps are soft rubber and have a coil spring that clips onto the plug terminal and a spike that has to be pushed through the lead insulation. The cable has to be fed though the cap, the terminal fitted and then the cable pulled back into place.

The car ones I never taken that much notice of.

I'm not aware of any that will need soldering.

 

[CreakyDecks]

Caps for small motorcyles can be used (and obtained singly of ebay for a couple of quid).

 

[William_H]

Car plug leads

Different ways. May be with a screw that goes down the centre of the wire. They are most likely to be hard plastic caps. Simple to fit. Just screw it on.

My outboard plug caps are soft rubber and have a coil spring that clips onto the plug terminal and a spike that has to be pushed through the lead insulation. The cable has to be fed though the cap, the terminal fitted and then the cable pulled back into place.

The car ones I never taken that much notice of.

I'm not aware of any that will need soldering.

Car plug leads these days are made of the resistive cable which is essentially a piece of string impregnated with carbon powder. This gives a resistance around 10000 to 50K ohms per foot. Connection is made by a crimp that cuts through the outer insulation or a self tapper screw thread that goes into the carbon inside the insulation. Plug leads were a source of failure on older cars. Modern cars with high voltage electronic ignition and molded leads are a bit more reliable. If the OP has copper wire centre for his plug lead then just bare the copper and clamp it under the plug terminal. The rubber cap was an attempt to keep salt water off the plug. (carry WD40 to spray the plug.) good luck olewill