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Author Topic: NGK Plug Wars: D7EA vs. D8EA  (Read 23924 times)

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Offline gravano

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NGK Plug Wars: D7EA vs. D8EA
« on: April 19, 2010, 10:50:07 AM »
I have D8EAs installed in my 75 CB550f. They run great once started, but it takes about 40 kicks to start my bike. It's in the 50s right now in Chicago. Will a switch to D7EAs render a marked difference? My timing is set right and the carbs are clean. I need to pull the plugs to get a better read on how it's running, but just curious if people have noticed a big difference between the two plugs -- enough to suggest I don't have other problems to diagnose.

Thanks
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Offline Frankenkit

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #1 on: April 19, 2010, 10:53:24 AM »
7s burn hotter and will help when its cold out, but you'd want to switch back to 8s when it gets hot out.
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Offline mlinder

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #2 on: April 19, 2010, 11:10:09 AM »
They will not help you start the bike more easily. They will only help it warm up more quickly once started, and remove less heat from the head while moving.
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Offline TwoTired

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #3 on: April 19, 2010, 11:16:03 AM »
Why are you running the D8s when the recommended plug is D7?

I hated D8s in my 550's.  They became cold blooded b@stards.

Battery fully charged?
Good points?
Gapped correctly?
Timing correct?
Good plug caps?
HT leads cracked?
New condensers?
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Offline Duke McDukiedook

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #4 on: April 19, 2010, 11:16:16 AM »
You should probably check your valve clearances if you are having that much trouble getting it started.
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Offline gravano

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #5 on: April 19, 2010, 11:54:20 AM »
The D8EAs were on the bike when I bought it. I didn't realize till recently.

Points and Timing are good. Not sure about the resistor caps; one has quite a bit of give.
The battery is charged, but I may replace soon. The guy I bought it from put in a new one in last year, but I think it may still need a new battery.
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Offline Tretnine

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #6 on: April 19, 2010, 12:58:49 PM »
I thought 8s were stock on all 550s. No?
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Offline TwoTired

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #7 on: April 19, 2010, 01:15:04 PM »
Quote from: Tretnine on April 19, 2010, 12:58:49 PM
I thought 8s were stock on all 550s. No?

No.

Owner's manual states D7ES, (NGK superceded the number with D7EA)
Or Denso X22ES.

I think all the other SOHC4s used D8 standard.  Not the 500 or 550, though.
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Offline BobbyR

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #8 on: April 19, 2010, 01:28:01 PM »
On the 750 in the Owners Manual they advise the 7s below 40F. Other than that they recommends 8's.
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Offline Tretnine

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #9 on: April 19, 2010, 02:38:50 PM »
Quote from: TwoTired on April 19, 2010, 01:15:04 PM
Quote from: Tretnine on April 19, 2010, 12:58:49 PM
I thought 8s were stock on all 550s. No?

No.

Owner's manual states D7ES, (NGK superceded the number with D7EA)
Or Denso X22ES.

I think all the other SOHC4s used D8 standard.  Not the 500 or 550, though.
[/quote

This is news. I'm running a couple of 78 550s and it looks like I need to move to hotter plugs on both.
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Offline gravano

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #10 on: April 19, 2010, 04:26:29 PM »
Well if it wouldn't affect the starting of the bike maybe I'll leave them in if they don't look too gunked up. This'll leave the resistor caps and battery as prime suspects for the 40-kick start problem. 
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Offline mlinder

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #11 on: April 19, 2010, 04:40:55 PM »
No, carbs, timing, valves and compression are the most likely suspects.
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Offline Duke McDukiedook

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #12 on: April 19, 2010, 06:03:43 PM »
Quote from: mlinder on April 19, 2010, 04:40:55 PM
No, carbs, timing, valves and compression are the most likely suspects.

+1000.  :)
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Offline Frostyboy

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #13 on: April 19, 2010, 07:00:02 PM »
Quote from: Dukiedook on April 19, 2010, 11:16:16 AM
You should probably check your valve clearances if you are having that much trouble getting it started.

Quote from: Dukiedook on April 19, 2010, 06:03:43 PM
Quote from: mlinder on April 19, 2010, 04:40:55 PM
No, carbs, timing, valves and compression are the most likely suspects.

+1000.  :)

+ yet 1 more  ;)
Remove the tank and try and start it cold whilst looking for stray H/T leakage from the plug wires. Do it in the dark so you can see the sparks. Mine was jumping to ground in a couple of places.
« Last Edit: April 19, 2010, 07:04:22 PM by Frostyboy »
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Offline Gcolgett

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #14 on: April 19, 2010, 07:11:38 PM »
Has anyone else used Champion R6G plugs? I went to Mexico and at times ran at 105+MPH and the CB550F never had a problem using them. Now they are hard to find since they are no longer made. They were a hotter plug than stock. George Colgett :)
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Offline TwoTired

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #15 on: April 19, 2010, 08:53:38 PM »
In hot weather and running hard, you actually want a colder plug to help get heat out of the chamber. FYI

I always used Champion plugs in my Chevy engines to make better power.

I was surprised when they didn't work as well in the Honda 550, and certainly didn't make the good power for as long as the NGKs did.  I haven't run Champions in the bike since the early 80s, based on that experience.
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Offline gravano

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #16 on: April 20, 2010, 07:35:09 AM »
Quote from: mlinder on April 19, 2010, 04:40:55 PM
No, carbs, timing, valves and compression are the most likely suspects.

Thanks everyone for the plug info. My bike kicks over a lot easier (10 kicks instead of say 40) with the choke fully open and the throttle open a little bit. I'm hoping this doesn't point to valve adjustment; I have big hands and lack that knack for precision that others seem to have. But does the diagnosis point that way?
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Offline Duke McDukiedook

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #17 on: April 20, 2010, 07:52:35 AM »
Yes.
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Offline gravano

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #18 on: April 20, 2010, 07:53:18 AM »
Dar!
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Offline Big Bob

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Re: NGK Plug Wars: D7EA vs. D8EA
« Reply #19 on: April 20, 2010, 08:23:10 AM »
Where in Chicago are you?
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