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Spark plug cap

Featured Replies

Hi, after some advice please, had my 4rt out the last weekend and it wouldn't start, went to take the plug out and the ht lead came straight out of the cap, I managed to bear some of the rubber back and ram it in the cap then sellotape, yes sellotape, it in...I managed three hours solid riding without it missing a beat, now can I just get a new cap or do I need to get one with a ht lead connected to it since bearing the wires back slightly?

Typically the replacement caps have a threaded point that screws onto the lead into the center core where the conductor is. Nothing too complex unless Honda has some special weirdness I don’t know about.

  • Author

So i can just buy a new cap and screw it straight on the ht lead?

Last time I replaced a lead cap it was just a screw on job...

I would check the cap you have now and see if it is a screw on type.  If so and you have enough extra length on the current lead you should be able to just cut the lead end flat and screw the cap straight on.

I would recommend that you pull the old cap back off and check it with a multimeter to make sure it’s not a resistor cap as well ?

If the HT lead is long enough, you may be able to cut it back 1/4” and screw your cap back on to it. Worth a shot :)

  • Author
1 hour ago, jackman290 said:

I would recommend that you pull the old cap back off and check it with a multimeter to make sure it’s not a resistor cap as well ?

Right, whats a resistor cap and whats it do mate?

  • Author
18 minutes ago, section swept said:

Stops your ignition signal from ruining Coronation Street.?

Coronation street? Is that part of the cylinder head? ?

Heh heh British television.

The cap has a resistor in it that limits the rise time of the spark current. That reduces the radio frequency electromagnetic waves emitted by the wire. So yeah, the BBC thanks you.

  • Author
7 hours ago, dan williams said:

Heh heh British television.

The cap has a resistor in it that limits the rise time of the spark current. That reduces the radio frequency electromagnetic waves emitted by the wire. So yeah, the BBC thanks you.

So what you're saying is i might not have to pay my tv licence if I'm doing them a favour by not interfering with the reception ? 

On 29/04/2018 at 3:02 AM, dan williams said:

No they’ll charge you a convenience charge for not interfering. That’s how a  bureaucracy works.

Yep and with the money they’ll produce even more dire crap!

It is my understanding that the resistance in the circuit will give longer spark dwell time and also protects the CDI from harmonics getting into the module, which could wreak havoc on the engine timing.

I’m not saying it will not run with zero resistance, but it could be a gamble with expensive electronics. This is confirmed by Steve at motoplat ? Just wanted to spread the word

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