Spark plugs and suppression Q and A

We often get asked about spark plugs, caps, HT leads and spark suppression. This question from Andrew in the UK is a good one.

Q: I have fitted a Tri Spark (Classic Twin) to my T140E but suspect that my standard plug caps and leads may no longer be suitable (both the caps and leads are expanding with heat and the caps keep jumping off the plugs)
Please can you confirm which type of plug and lead I should fit?

A: The plug cap must be a good fit or it will continue to fall off. The ones pictured above from the sets we sell are tight fitting and click positively onto the spark plug. The HT wire is simply cut to length and screwed into the socket for easy connection to the cap.

Q: Are resistor plugs (NGK BPR7ES) OK to use instead of a resistor cap? Yes

Q: My plug wires are copper core.  Is this OK or should they be replaced with carbon core?

A: We don't recommend carbon core leads unless both molded end fittings can be retained. Carbon leads are great for cars but no so good for bikes with high vibration and heat. Cutting carbon leads and fitting universal caps is generally not a good practice. Automotive leads are often odd colours and have unsightly printing down the length.

Q: Can I use Iridium plugs with the Tri-Spark ignition?

A: Some people will claim an improvement changing to iridium. There's no harm in it however for the cost you might be better off to buy 2 sets of the standard type to keep on hand for spares.

Q: Do I need spark suppression with the Tri-Spark ignition?  

A: Spark noise is like the electrical equivalent of a Tsunami or Tornado. The electrical noise interferes with all sorts of electronic items including the ignition and charging systems so it's best to have either resistor type plugs or caps (not both) fitted to your engine to reduce the noise and keep things running smoothly. Keeps your GPS happy too!