Spark plugs, gaps, etc., with Tri-Spark ignition

I think the best thing to do is follow the ignition system manufacturer’s advice.

In the case of Tri-Spark, they call for either a resistive plug or a resistive cap, and they explicitly say not both.



They designed the system, so they know what is more robust and reliable.


I really like the Denso plugs - only because they don’t foul like others I have used, and they seems to last forever.

I have also not yet had a bad Denso plug - counterfeiting seems a common issue with the NGK ’R’ plugs - they are even getting into the supplier chain of the reputable sellers, which is a worry.

I use:

• Denso IW22 for a pair of standard coils

• Denso VW22 for dual output single coil (remembering that with these coils, the spark jumps from centre electrode to ground electrode on one side, but ground electrode to centre electrode on the other)

gtiller said:

I think the best thing to do is follow the ignition system manufacturer’s advice.

In the case of Tri-Spark, they call for either a resistive plug or a resistive cap, and they explicitly say not both.

View attachment 19901

They designed the system, so they know what is more robust and reliable.


I really like the Denso plugs - only because they don’t foul like others I have used, and they seems to last forever.

I have also not yet had a bad Denso plug - counterfeiting seems a common issue with the NGK ’R’ plugs - they are even getting into the supplier chain of the reputable sellers, which is a worry.

I use:

• Denso IW22 for a pair of standard coils

• Denso VW22 for dual output single coil (remembering that with these coils, the spark jumps from centre electrode to ground electrode on one side, but ground electrode to centre electrode on the other)

Click to expand...

This thread is a few months old.

The OP (Chris Larkin) asked about using Iridium plugs with a Tri-Spark.

It was dennisht who posted in the last few hours regarding the use of resistor plugs with a Boyer ignition.

FWIW - running copper core champion plugs, non-resistor caps, but resistor wire. wire ohms out aaround 1000-1100 for the 11 inch "home grown" HT leads. running early tri-spark unit, OE type lucas 6V coils, and podtronics assembly. seems to be running OK and without issues, although it may be a "time will tell" thing.

Champions on mine set at 28 and never misses a beat. Changed at 5,000 miles due to local running.

ELLIS

This is about aircraft spark plugs but may be of general interest. For my bike, as long as it's running well any time have them out I give them a quick glass beading, check the gap, and reinstall. For my plane's engine I don't have access to a bomb tester like when I was a young man working on planes full time so when I have the plugs out for inspection time I check the resistance as well as cleaning/gapping them. The below article deals with a bad batch of champion aircraft plugs.

You can imagine the fun of pulling 28 plugs each out of a big radial clean, gap, test, and install!

Here's another aviation write-up from a different manufacturer. Yes, I know, airplane not motorcycle but I think it contributes to the general spark plug knowledge:

JimNH said:

...You can imagine the fun of pulling 28 plugs each out of a big radial clean, gap, test, and install!..

News & Media: The latest news in general aviation

Your trusted general aviation news source, covering the latest in aircraft, gear, technology, and advocacy across the country.

blog.aopa.org

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28 plug Radial? That warrants a picture.
Picture please...and it's habitat.

7 cylinders per row, 2 rows with 2 plugs per cylinder = 28 plugs? DC 3 and many others.

Now if they could make one small enough to fit in a featherbed frame?

Tiger Shark said:

7 cylinders per row, 2 rows with 2 plugs per cylinder = 28 plugs? DC 3 and many others.View attachment 19965

Click to expand...

Try an R4360. 28 cylinders - 56 spark plugs!