What spark plug for Boyer ignition?

[stlukey]

Hi, new member here. I recently purchased a ‘72 750 roadster project. It has the Boyer ignition. Do I need to use a non resistor spark plug or a resistor type? Or does it matter? I couldn’t find a definitive answer searching online. Thanks. John

 

[L.A.B.]

Welcome.

I recently purchased a ‘72 750 roadster project. It has the Boyer ignition. Do I need to use a non resistor spark plug or a resistor type?

Depends on which particular "Boyer" it is? The most common is the black box MkIII and MkIV.

Boyer Bransden Electronics Ltd

"Why Do I Need To Use Suppressed Plug Caps?
MKIII and MKIV do not require suppressed plug caps for operation although we recommend using supressed 5000 ohm plug caps. Micro Digital and Micro Power units must be fitted with supressed plug caps*. Plug caps fitted with suppression resistors are usually fitted to prevent radio interference. Radio interference (noise) can cause more complex electronic circuits like radios and computers to malfunction.

Our Micro Digital and Micro Power ignition systems contain a small computer operating at high speed that can be adversely affected by radio frequency interference. Symptoms can range from refusal to start to intermittent engine stalling symptoms. Use of non-suppressed plug caps has been known to cause permanent damage to the ignition unit."

*(or resistor plugs)

 

[alan hodge]

here we go...i favour nonresistor caps/solid copper core wires and autolite AP63 plugs works for me as Farina on the Little Rascals said...'let the argument begin'

 

[Derek Wilson]

I really don't think it matters - but I run resistor plugs out of convenience

 

[Time Warp]

Do I need to use a non resistor spark plug or a resistor type? Or does it matter?

Yes it matters.
Either a resistor spark plug or a suitable Ohm resistor spark plug cap and am sure there are bikes out there running both.

NGK do both with and without resistor caps.

My Sunbeam has no resistance when I got it, the television I was told did not like that when in range, its antiquated ignition was not bothered.

 

[CanukNortonNut]

N7YC Champions, copper core wires will work for boyers Mk111 and Mk4

 

[acotrel]

I think resistor spark plugs were introduced to reduce interference with the old type of TVs. What is probably more important is the heat range.

 

[L.A.B.]

I think resistor spark plugs were introduced to reduce interference with the old type of TVs.

Something resistor plug caps had already been doing for the previous (30 or longer?) years.

 

[Mart UK]

We should remove the resistors, as a protest against the total sh**e on TV. 'Resistance us futile'?

 

[seattle##gs]

NGK make resistor caps that are only 1000 ohms and look identical to the 5k caps. LB01E is the number and the cap accepts the round nut instead of just the threaded post. Champion N7YC are noticeably better than the NGK plugs.