Author Topic: Plugs?  (Read 731 times)

Offline MikeFossl

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Plugs?
« on: April 03, 2016, 01:30:34 PM »
Ok, just changed the plugs and find I have both NKG BPR7ES and BP7ES lying around.  What should I be using and why? :-/
1985 R65

Offline Bob_Roller

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Re: Plugs?
« Reply #1 on: April 03, 2016, 02:04:32 PM »
I don't know if it really make difference or not, but it is recommended to use non-resistor type plugs .
I wasn't aware of this and used Bosch platinum resistor plugs for a few years, got 4 plugs for $7, close out special, never had any operational issues when using them .
I won't ever use them again, the center electrode was recessed into the  ceramic, best I could tell, the gap was over 2 times what it was supposed to be !!!
This was at 8,000 miles, 11,000 km .
I've gone to NGK plugs ever since Bosch plugs stopped being available in non resistor type .
If you put non-resistor ignition leads on the bike, then you can use the more common resistor plugs .
« Last Edit: April 03, 2016, 02:07:06 PM by Bob_Roller »
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline georgesgiralt

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Re: Plugs?
« Reply #2 on: April 03, 2016, 02:09:52 PM »
If you use standard OEM cables, you have to use the BP7ES. If you have non resistor caps, you have to use resistor plugs with 5K Ohm resistor built in. As the resistor value is not written on the package, you should check the maker's literature to ascertain it.
The rsistor value will change the timing a little bit and the overall radio interference status.

Offline Tony Smith

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Re: Plugs?
« Reply #3 on: April 03, 2016, 03:15:32 PM »
Quote
If you use standard OEM cables, you have to use the BP7ES. If you have non resistor caps, you have to use resistor plugs with 5K Ohm resistor built in. As the resistor value is not written on the package, you should check the maker's literature to ascertain it.
The rsistor value will change the timing a little bit and the overall radio interference status.

I think you will find the resistance rating is 10k Ohm. However depending on whether you have Bosch, Beru, NGK or ______? Plug caps and depending on what is used as the conductor in the spark plug leads the resistance will be anything from 5K~15K Ohm.


If you run radio equipment that is electrically connected to the bike suppressing the alternator is the biggest problem (fortunately easily solved), The main thing with sparkplug leads and caps is that there are no conductor gaps or cracks in the cap - anything that will allow a arc will cause interference, but just about any system in good working condition will be fine.

In my experience the major cause of ignition interference in pre 1981 BMW is less than full insertion of the plug leads into the coils. The old type 6volt coils have a fairly lazy existence and will throw an arc across a very large gap and not be noticeable from a performance point of view.

The later dual coils are "noisy" all by themselves, but generally not to the point of being annoying - the inside of a helmet not being a HiFi environment....
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline Barry

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Re: Plugs?
« Reply #4 on: April 04, 2016, 04:04:45 AM »
As has been said you must have some resistance in the ignition leads/plugs for suppression and to protect the electronic ignition from damage. More than the min 5000 Ohms resistance is probably not going to be a problem with a electronic ignition as the system will have plenty of spark energy in reserve.

To be clear it will weaken the spark a little as some energy will be dissipated in the resistor. Ohms law says that must be the case.  It's sometimes said that an extra 5000 ohms is nothing compared to the almost infinite resistance of the spark gaps but that's a mistaken view. The 5000 ohms should be compared with the resistance of the spark gap once the air in the spark gap is ionised and the spark is under way which will be something much less than infinite.  

Bottom line is it's not an issue for electronic ignition but more of a potential problem with points ignition where there is less energy in reserve. Stock and therefore ideal resistance for a points system is 1000 ohms but many find it still works OK with 5000 ohms. I use 5000 ohm NGK caps with points  just because 1000 ohm caps are not available in the UK. I wouldn't go higher though.
Barry Cheshire, England 79 R45

Offline crguy

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Re: Plugs?
« Reply #5 on: July 05, 2020, 05:29:11 PM »
Hello all, just downloaded NGK chart and they list 0.20 as the gap...

Offline Bob_Roller

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Re: Plugs?
« Reply #6 on: July 05, 2020, 08:22:56 PM »
BMW manuals state a plug gap of .028 in .
In the real world I don't know if it makes much of a difference .
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline jp9094

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Re: Plugs?
« Reply #7 on: July 05, 2020, 09:36:14 PM »
Hi all,
Just changed my plugs also. They are the proper Bosch plugs and are available from Bob's BMW in Maryland. First thing I noticed (after 3 1/2 years of using NGK) was an immediate increase in my milage! When I acquired the bike (1983 r 65 LS) 5 years ago,I was getting around 220 miles to a tank. Until recently I was only getting around 175 miles ( and less sometimes). The new plugs ( I had set the valves a month ago) got me 205 miles/tank, and they were installed on a half tank! Am monitoring my milage, but am confident the right plugs get the best milage. Gap was set to 0.25 for those who are curious.

FWIW
"It's what you learn, after you know it all, that counts"

Offline mrclubike

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Re: Plugs?
« Reply #8 on: July 07, 2020, 10:38:13 PM »
I am using Champion N9YC (Part# 300) Non resistor
And I am getting 49 miles to the US gallon
Readily available at most auto parts stores 

Kinda pricey  ;D
But they match my really cool Champion 5Kohm boots 8-)
« Last Edit: November 05, 2020, 04:09:44 PM by Justin B. »
1982 R65 running tubeless Snowflakes
2004 R1150R

Offline dogshome

  • Posts: 116
Re: Plugs?
« Reply #9 on: August 02, 2020, 05:45:25 PM »
I have the later orange coil, copper leads, NGK 0 ohm caps and NGK BPR7EIX 5K resistor plugs. I measured the resistances.

The original 5K resistor leads, BP7ER plugs  and metal caps had no issues, but she has taken on a very UJM starting and running characteristic since changing! I had to look down at 70MPH to check it was still only 2 cylinders.

She likes the plugs (and more likely) the new leads. The electronic balancer and new ignition parts has changed the bike in more than a subtle way. No more buzzing in the footpegs at 50 in 5th gear and slow corners can be lazily run round in third without dropping to second.

The R65 is not a lugger and I am gentle when opening up at low revs in higher gears, but she is much happier in all respects now.
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O