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Thread Like Summary
Excalibur, gavin eisler, Hillbilly bike, kevin, MarksterTT, PEH, The Bonneville Shop, wilksville
Total Likes: 9
Original Post (Thread Starter)
#835750 01/06/2021 6:01 PM
by The Bonneville Shop
The Bonneville Shop
Any of you guys have an opinion about using the NGK BR7ES or BR8ES spark plugs with either points or electronic ignitions in our vintage British twins? Apparently NGK has discontinued the B7ES and B8ES, as well as the projected-tip versions, BP7ES and BP8ES.
Liked Replies
#835775 Jan 6th a 07:03 PM
by L.A.B.
Originally Posted by MarksterTT
Do Pazon Smart-fire,Tri-spark or Boyer require a resistor cap or plug? These are the only ones that would concern me and maybe a few others....Mark

Oh, and maybe the Lucas Rita since I inherited a couple of those...thanks, Mark

Digital ignitions usually need either resistor caps or plugs but analogue ignitions do not although EI manufacturers often recommend they are used.
"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."

Resistor plug caps or plugs required?

Boyer Micro MkIII, MkIV = No
Boyer Micro-Digital = Yes
Boyer Micro-Power = Yes

Pazon Sure-Fire = No
Pazon Altair = Yes
Pazon Smart-Fire = Yes

Tri-Spark = Yes,
Lucas Rita = No.
Wassell Vape = No
2 members like this
#835759 Jan 6th a 06:16 PM
by triton thrasher
triton thrasher
My experience (rather than opinion) is that 5 kohm in the HT circuit makes no difference to the performance of points or electronic ignition.

Recently I’ve been using a dual output coil with two resistor spark plugs, so that’s 10 kohm in the HT circuit. It works just fine, with Wassell electronic ignition.
2 members like this
#835767 Jan 6th a 06:29 PM
by triton thrasher
triton thrasher
Originally Posted by MarksterTT
Not being a wise ass here, but since in your experience it made no difference than why use them in your install? I'd seriously like to know and thanks tt...Mark R.

Because I fancied fitting iridium plugs and couldn’t find them without resistors.
1 member likes this
#835769 Jan 6th a 06:31 PM
by triton thrasher
triton thrasher
Be as wise an ass as you want- you’re not going to offend me!
1 member likes this
#836045 Jan 9th a 01:19 AM
by NickL
Just use B7EV or B8EV plugs instead of ES type.
1 member likes this
#836170 Jan 10th a 11:23 AM
by triton thrasher
triton thrasher
This aeroplane guy did some rudimentary tests, which don’t really answer the question about any palpable effect of low value resistor (5,000 kohm) in an old bike, but still quite interesting.
1 member likes this
#839814 Feb 12th a 04:46 PM
by desco
I'm sold on Denso. I had a problem on the 68 that only happend upon leaving a certain stop sign after a hard uphill canyon run and needing to to cross four lanes of speeding truck traffic. The bike would stutter a bit. Not much but at certain times it could be heart stopping. I chased that stutter for years. Denso cured it.
1 member likes this
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