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Author Topic: Resistor plugs?  (Read 8040 times)

Offline BlitzenGruv

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  • My first BMW. Been riding old British forever..
Resistor plugs?
« on: April 23, 2016, 05:44:09 PM »
Forgive me, as I'm sure that this has been covered too many times.
'92 K100, 4 valve. I've read elsewhere that these require resistor plugs, and that damage to the ignition system can occur if non-resistor plugs are used.
Just bought some DR7EA plugs. Removed the old plugs, and they are D7EA, non-resistor. The two spare plugs I found in the storage compartment are Bosch X5DC, also non-resistor plugs. No telling how long this thing has run on non-resistor plugs.
Is there any chance that this has damaged the ignition unit?
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  • Crossville, TN
  • '92 K100rs, 16v, '71 BSA Lightning, '72 Triumph Bonneville, '72 Triumph Trident
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Offline johnny

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Re: Resistor plugs?
« Reply #1 on: April 23, 2016, 08:15:47 PM »
greetings...

im not sure...

2 valve k75 + k100 = bosche X5DC = inge k D7EA ...
4 valve K100 + K1 = bosche XR5DC = bosche XR7LDC = inge k DR7EA...
4 valve k1100 = bosche XR7LDC = inge k DR7EA...

the xr7ldc is a double banger as now recommended by the oem...

do yourn doo dillergence...

 :xeno

j o
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Offline Laitch

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Re: Resistor plugs?
« Reply #2 on: April 23, 2016, 08:42:09 PM »
Quote from: BlitzenGruv on April 23, 2016, 05:44:09 PM
Forgive me, as I'm sure that this has been covered too many times.
Unforgiven.
Gap the new plugs, install them and go riding, Blitzen. It's too late for worrying about the past. The weather is too good for that. If it doesn't run as well, you can always reinstall the old ones. How many miles on the bike?
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Offline BlitzenGruv

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Re: Resistor plugs?
« Reply #3 on: April 23, 2016, 09:10:23 PM »
Of course, once I had a look the plug caps are 5K resistor caps. Must exchange plugs for D7EA.
Old plugs don't look bad, but one shows some oil.
Old plugs cleaned and back in, gotta ride tomorrow.
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  • Crossville, TN
  • '92 K100rs, 16v, '71 BSA Lightning, '72 Triumph Bonneville, '72 Triumph Trident
You say I'm schizophrenic, but I don't believe we are.

Offline BlitzenGruv

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Re: Resistor plugs?
« Reply #4 on: April 23, 2016, 09:57:30 PM »
FWIW: Virtually all old Brit bikes used the same plugs. Non-resistor, unless you changed something.
Of course, we all make our own plug wires and pray to Druid gods that everything works. LOL
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  • Crossville, TN
  • '92 K100rs, 16v, '71 BSA Lightning, '72 Triumph Bonneville, '72 Triumph Trident
You say I'm schizophrenic, but I don't believe we are.

Offline Inge K.

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Re: Resistor plugs?
« Reply #5 on: April 24, 2016, 03:36:12 AM »
Quote from: BlitzenGruv on April 23, 2016, 09:10:23 PM
Of course, once I had a look the plug caps are 5K resistor caps. Must exchange plugs for D7EA.

Both 2V and 4V K100's have 5K ohm caps (and 1K ohm in the connector at the coil end).
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Offline The Mighty Gryphon

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Re: Resistor plugs?
« Reply #6 on: April 24, 2016, 09:44:12 AM »
Quote from: Inge K. on April 24, 2016, 03:36:12 AM
Quote from: BlitzenGruv on April 23, 2016, 09:10:23 PM
Of course, once I had a look the plug caps are 5K resistor caps. Must exchange plugs for D7EA.

Both 2V and 4V K100's have 5K ohm caps (and 1K ohm in the connector at the coil end).

Now I;m really cornfused.  My ;92 K100RS has DR7EA plugs and stock wires.  As I recall, the owner;s manual specifies Bosch resistor plugs. 
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Offline Inge K.

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Re: Resistor plugs?
« Reply #7 on: April 24, 2016, 11:04:47 AM »
Quote from: The Mighty Gryphon on April 24, 2016, 09:44:12 AM
Quote from: Inge K. on April 24, 2016, 03:36:12 AM
Quote from: BlitzenGruv on April 23, 2016, 09:10:23 PM
Of course, once I had a look the plug caps are 5K resistor caps. Must exchange plugs for D7EA.

Both 2V and 4V K100's have 5K ohm caps (and 1K ohm in the connector at the coil end).

Now I;m really cornfused.  My ;92 K100RS has DR7EA plugs and stock wires.  As I recall, the owner;s manual specifies Bosch resistor plugs.

Then everything is as it should be.............
4V have both resistor caps, connectors and plugs.
2V have only resistor caps and connectors (and different coils).
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Offline Martin

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Re: Resistor plugs?
« Reply #8 on: April 24, 2016, 04:24:22 PM »
Local BMW trained mechanic told me to run resistor plugs in my 92 K75S. I ran one set and it did not appear to make any difference, so I went back to non resistor plugs. And I am running non OEM NGK 5 ohm plug caps.
Regards Martin
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Offline BlitzenGruv

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Re: Resistor plugs?
« Reply #9 on: April 24, 2016, 06:56:16 PM »
Must be OK. I put the resistor plugs in and rode almost 90 miles today with no problems.
Thanks  :clap:
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  • Crossville, TN
  • '92 K100rs, 16v, '71 BSA Lightning, '72 Triumph Bonneville, '72 Triumph Trident
You say I'm schizophrenic, but I don't believe we are.

Offline TimTyler

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Re: Resistor plugs?
« Reply #10 on: April 24, 2016, 09:02:12 PM »
About 10k miles ago I switched to Magnecor 3508 8.5mm ignition cables (no added resistance) and Autolite Xtreme Sport Iridium Spark Plug - XS4164 (suppressor type).

I thought I noticed an immediate improvement in starting and engine smoothness, but who knows. I had a weird engine knock at 3krpm and it disappeared with the new plugs.
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