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Recomendation for RC04 CB750FD None Resister Plug Caps

MickMick

CB750 Enthusiast
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Location
Retford, Nottinghamshire, England
Hi all,
I have both NGK resister plugs (5k) and plug caps (5k) and this looks like too much on the spark as I have to set a small gap. I want to drop one of the resisters on each plug but do not want to replace my iridium plugs so looking for a set of recommended plug caps for this model please. UK based.
Regards
Michael
 
I'm surprised you're running iridium plugs -- you get a slightly thinner spark when running those in exchange for the tougher electrode. Copper gets you the highest performance due to its high conductivity. It's the OEM plug on our machines, and they're very easy to check and change.

Iridium is great for street cars due to its increased longevity (especially for cars with difficult spark plug access) but in an air-cooled motorcycle with easy access they seem like a waste of money to me. The difference is probably not very much though and you've already spent the money.

I believe NGK makes non-resistor caps. Do your caps have a part number on them?
 
Yes ,hi. I bought the iridium plugs which seems to help with an irratic spark. The old plugs were ngk dr8es, iridiums are ngk dr8eix. The caps are the standard ngk, 1&4 are the angled SD05's and 2&3 are the straight XD05's. The SD ones do have a removable resister, but the XD's do not. They all measure at approx 5k ohm and are stamped as such. I was thinking maybe to use a Champion cap, but cannot see which ones to go for. Has anyone used Champion caps?
Michael
 
Fwiw..having owned bikes over 40 years now..NGK seemed to solve my issues and I gave Bosch away(even in Bmw days).... and I recall the BMW plug that were champion made in Canada in the BMW box at $22a plug in the 1980s!

My experience..
Change to NGK plugs/caps/ splicers..no ignition hiccups..
 
Yes ,hi. I bought the iridium plugs which seems to help with an irratic spark.
Replacing spark plugs won't solve that problem, and that is what you need to fix!

Intermittent failures are a pain to diagnose, but that has to be something other than the plugs. My suspicion would be at least one poor electrical connection in the ignition system. Corrosion can cause intermittent wiring failures, and so can loose connections.

What you should do is take a multimeter and test resistances through the wiring harness. Definitely check the integrity of the frame ground next to the ignition coils, and the terminals that connect to the igniter units and coils and timing rotor.

If all of your wiring connections are near-perfect with no visible looseness or corrosion, and their resistance tests are very close to zero, then your next suspicion should be a failing coil or igniter. Both can also be tested with a multimeter.
 
Replacing spark plugs won't solve that problem, and that is what you need to fix!

Intermittent failures are a pain to diagnose, but that has to be something other than the plugs. My suspicion would be at least one poor electrical connection in the ignition system. Corrosion can cause intermittent wiring failures, and so can loose connections.

What you should do is take a multimeter and test resistances through the wiring harness. Definitely check the integrity of the frame ground next to the ignition coils, and the terminals that connect to the igniter units and coils and timing rotor.

If all of your wiring connections are near-perfect with no visible looseness or corrosion, and their resistance tests are very close to zero, then your next suspicion should be a failing coil or igniter. Both can also be tested with a multimeter.
Ok. Will do. Cheers
 
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