Author Topic: Spark plugs  (Read 832 times)

Offline florence

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Spark plugs
« on: April 19, 2019, 04:20:12 PM »
I'm just about to replace my plugs.  Currently has worn out DR7ES but looking at manual it say D7ES.  Does anyone know aht is correct and best place to buy them.  I have aftermarket air filters and laser 4-1 exhaust if that infleunces decision. 1974 CB500/4
« Last Edit: April 19, 2019, 04:25:08 PM by florence »

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: Spark plugs
« Reply #1 on: April 19, 2019, 04:34:33 PM »
DR denotes the plugs are fitted with resistors. Only fit DR tyre if your plug caps are not resisted. D7EA are non resisted, so you need resisted plug caps fitted. You shouldn't use both resisted caps and plugs together, just one or the other.
« Last Edit: April 19, 2019, 05:07:34 PM by Nurse Julie »
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Offline florence

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Re: Spark plugs
« Reply #2 on: April 19, 2019, 04:59:22 PM »
Hey thanks, I did not know that.  Gosh, I think the caps I have are resistor (NGK) so looks like I should get D7ES.  THanks again,

Offline Brian.

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Re: Spark plugs
« Reply #3 on: April 19, 2019, 05:37:41 PM »
Hello Florence,

I bought my plugs a couple of weeks ago, and a set of plug caps, from here:- https://www.gsparkplug.com/

It was the best deal I could find, and they came in a couple of days.

I can definitely second Nurse Julie's comment above regarding not using resistor plugs and resistor plug caps together, it was one of the reasons why my CB550 ran so badly when I bought it.

What probably made mine worse still was that the resistance of the plug caps when checked on a multimeter (if you have access to one) was very high, they should be 5k ohms; two of mine were about 9k ohms and the other was 13.  It's a wonder really that there was any spark at all I guess.

New D7ES plugs and new caps, less than £20 all in, and ignition problems all sorted.

I hope this helps!

Brian.

Offline florence

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Re: Spark plugs
« Reply #4 on: April 19, 2019, 07:15:27 PM »
wow Brian, great site, shall order today.  My ignition has been a bit unreliable lately, no.3 keeps cutting out.  Replaced coils which were always bad in the wet.  Now with these plugs should all be good.  Thanks to both of you for great advice.

Steve

Offline SteveD CB500K0

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Re: Spark plugs
« Reply #5 on: April 19, 2019, 07:34:48 PM »
Of course, resistor plugs/caps were required in the 70s because the ignition systems broadcasted in the FM frequency band (98-108 MHz).

Nowadays nobody broadcasts there (not that we care about anyway)

Our bikes would have to be nuclear powered to interfere with DAB or 3G/4G bands


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Offline Brian.

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Re: Spark plugs
« Reply #6 on: April 19, 2019, 07:53:33 PM »
wow Brian, great site, shall order today.  My ignition has been a bit unreliable lately, no.3 keeps cutting out.  Replaced coils which were always bad in the wet.  Now with these plugs should all be good.  Thanks to both of you for great advice.

Steve
OK Steve, well, if it's any help, the plug caps I ordered for mine were described on the website as 2no "VD05F black (8052)" and 2no "XD05F black (8072)" and they are a straight swap for the knackered ones that were fitted to me bike when I bought it if that's any help.  Please do check for yourself that they are right for you though, before you part with your money!

Those and four plugs plus P&P and VAT came to £19.46 total.  Which I thought was more than OK to be honest.

Hope this helps!

Brian.

Offline Johnwebley

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Re: Spark plugs
« Reply #7 on: April 19, 2019, 08:27:54 PM »
Hello Florence,

I bought my plugs a couple of weeks ago, and a set of plug caps, from here:- https://www.gsparkplug.com/

It was the best deal I could find, and they came in a couple of days.

I can definitely second Nurse Julie's comment above regarding not using resistor plugs and resistor plug caps together, it was one of the reasons why my CB550 ran so badly when I bought it.

What probably made mine worse still was that the resistance of the plug caps when checked on a multimeter (if you have access to one) was very high, they should be 5k ohms; two of mine were about 9k ohms and the other was 13.  It's a wonder really that there was any spark at all I guess.

New D7ES plugs and new caps, less than £20 all in, and ignition problems all sorted.

I hope this helps!

Brian.

 worth bearing in mind,as the caps get used,the resister can burn out,and give a much higher reading,
so if you start getting ignition issues,check the caps as well !!!
lifelong motorcycle rider,and fan

Offline florence

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Re: Spark plugs
« Reply #8 on: April 19, 2019, 08:30:46 PM »
hmm, D7ES out of stock but they do have D7EA.  Does anyone know the difference?

Offline Brian.

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Re: Spark plugs
« Reply #9 on: April 19, 2019, 08:37:32 PM »
hmm, D7ES out of stock but they do have D7EA.  Does anyone know the difference?

Well, I don't; but however you look at it they are wrong in some way & you don't want another set of wrong ones so maybe best hang fire until they come in to their stock, or buy from somewhere else?

Brian.

Offline Nurse Julie

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Re: Spark plugs
« Reply #10 on: April 19, 2019, 08:38:38 PM »
No idea what the difference is but EA will be fine. We use D7 or D8EA on all our old Hondas.
Edit.....and they all run spot on 😀😀
« Last Edit: April 19, 2019, 08:40:32 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Seamus

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Re: Spark plugs
« Reply #11 on: April 20, 2019, 12:18:19 PM »
Out of curiosity, what is the effect of running non resisted plugs and non resisted caps?
I have dyna ignition and coils, non resisted plugs and caps. Should I be running DR77ES.

Offline K2-K6

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Re: Spark plugs
« Reply #12 on: April 20, 2019, 01:53:20 PM »
I feel these combustion chambers were researched and developed to use resisted ignition system.

It's often just referenced to radio interference,  but it changes the length of spark which is intrinsic to combustion chamber design. I don't think they should be run without resistance.

Offline Bryanj

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Re: Spark plugs
« Reply #13 on: April 20, 2019, 04:41:08 PM »
D7EA is the new number for D7ES in the NGK catalogue.

Offline deltarider

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Re: Spark plugs
« Reply #14 on: April 22, 2019, 08:08:44 AM »
I feel these combustion chambers were researched and developed to use resisted ignition system.

It's often just referenced to radio interference,  but it changes the length of spark which is intrinsic to combustion chamber design.
Any proof for that? The internet is full of unproven claims.