Topic: NGK discontinuing their spark plug caps

[Flyin900]

I have been searching for a number of different styles of NGK plug caps recently and on another forum they indicated that they were discontinued by NGK. In fact an email from the tech department of NGK confirmed and copied on that forum that NGK were now out of supplying the older style resistor and non resistor plug cap’s altogether.

The tall 102 degree caps are out of stock both locally and at a few US vendors I frequently use. They are the VD05F series if I recall the part number.

So just a FYI that other sources will be necessary at some point since the caps do fail especially the resistor style after  40+ years of service.

[Kevin]

Thanks for the information!
I heard from my sources in Japan that a lot of items needed to rebuild a CB400F engine are getting extremely hard to source.
They are dipping into their private reserves to service customers bikes.

[fizzlebottom]

Randakk's seems to still have a number of choices for spark plug caps. Looks like a lot of them are labeled K&S, so a different manufacturer from NGK. Hopefully they remain available but I can't imagine there are many manufacturers of vintage style spark plug caps left in the world.

[Alan F.]

It does seem like a good time to begin stocking up on plugs and caps for bikes we intend to keep. Non-resistor plugs and resistor caps seemed to be the first to stop production at NGK, eventually the corresponding resistor plugs and non-resistor caps will end as well, and we'll be cleaning up old plugs to keep riding.

[PeWe]

The NGK caps no longer in stock where I bought mine in UK before Brexit. https://www.gsparkplug.com/

Plugs silly cheap here back then.
Just over 1 GBP for Denso, around 1.8 GBP for NGK. Low shipping.

Price doubled since then here available.

I just checked my stock, 7 complete sets of caps, more than 90 new plugs, mixed NGK D8EA and Denso X24ES-U.
I can clean ca 30 plugs not much used, just pitch black sooty.

vintagecb750 has.

I remember an earlier thread where the angled cap was up that I looked up the part number for.

http://forums.sohc4.net/index.php/topic,192177.msg2239260.html#msg2239260

I'm good, no need to order
I'm sure there are other parts.....

[HondaMan]

If the caps disappear and we are forced into the boot-only arrangement, use the resistor type of sparkplug instead.
D8ES-L becomes DR8ES-L (use this instead of D8EA in any case, as D8EA are too cold for all but interstate use).
X24ES-U becomes X24ESR-U
D7EA becomes DR7EA
X22ES-U becomes X22ESR-U

[CycleRanger]

This does suck. However I'm sure some company will step in to meet the demand and produce equivalent caps.
They won't be NGK but these caps shouldn't hard for some resourceful company to reproduce, they're not a super-high tech item.

[Deltarider]

So far already three SOHC Four specialists (UK and The Netherlands) who work our bikes on a daily basis, advise NOT to use R(esistor) plugs. From personal experience I agree with them.

[Shtonecb500]

hopefully a few people at vintage days has massive old stock out on tables.

[fizzlebottom]

So far already three SOHC Four specialists (UK and The Netherlands) who work our bikes on a daily basis, advise NOT to use R(esistor) plugs. From personal experience I agree with them.

Care to elaborate on why this may be the case?

[Deltarider]

So far already three SOHC Four specialists (UK and The Netherlands) who work our bikes on a daily basis, advise NOT to use R(esistor) plugs. From personal experience I agree with them.

Care to elaborate on why this may be the case?

I don't have the answer. May have to do with our bikes being dirty pigs, meaning running fat in low rpms. My R plugs were always on the black side and I have had two of these R die out of the blue. Later I read the specialists warning like this one here. Read the ''Description'' in:
https://honda4parts.nl/product_info.php?products_id=332&language=en&ceid=704b90f730c4af56beb7a9411c885a4c And I remember having read in the UK site restorer Trigger cured some bikes that wouldn't run right by swapping the R plugs for standard. And there was this third supplier of parts for CB Fours in The Netherlands who strongly advised not to use the R's in our bikes.

[fizzlebottom]

I don't have the answer. May have to do with our bikes being dirty pigs, meaning running fat in low rpms. My R plugs were always on the black side and I have had two of these R die out of the blue. Later I read the specialists warning like this one here. Read the ''Description'' in:
https://honda4parts.nl/product_info.php?products_id=332&language=en&ceid=704b90f730c4af56beb7a9411c885a4c And I remember having read in the UK site restorer Trigger cured some bikes that wouldn't run right by swapping the R plugs for standard. And there was this third supplier of parts for CB Fours in The Netherlands who strongly advised not to use the R's in our bikes.

One point of curious confusion that I have regarding ignition resistance is that the CB650 came with both resistor plugs AND resistor caps, totaling 10k resistance per cylinder and 20k resistance per ignition coil. Some of the other bikes at the time had the same setup, but not at all. The CBX for example had resistor caps but non-resistor plugs, but the CB900 had both components with 5k resistors.

So if time goes by and there are no more resistor caps, and I have to replace mine, do I just go with non-resistor caps + resistor plugs? It'll change the total resistance but I don't really know yet how that would impact the running condition of the bike.

[Alan F.]

No..... It'll interfere with my AM radio reception!

[HondaMan]

Beginning in 1973, Honda installed resistor plugs (DR8ES-L and some X24ESR-U) in the CB750 and CB550 sent to Canada. They also were found in these bikes then in California and New York, out of their crates from Honda, with the original 7.5k plug caps as well.
By mid-year 750K4 (around 3/74 production) these plugs disappeared for D8ES-L or X24ES (not the "Hot U") in the crated bikes  and the new 10k resistor caps came on them instead.

In practice I noticed they stayed cleaner longer than the non-resistor plugs and tried some in my own 750. I discovered they required the mainjets be leaner (105 instead of 110 size) to stay clean. Interestingly enough, so did Honda: the K4 came with the 105 mainjets, too, as did all the later 750s.

Today: I install resistor plugs in the 750s (including my own) when the bike will be ridden primarily in-town, and spec Regular grade gas be used. This keeps the plugs cleaner.

[TwoTired]

The resistance in plugs or caps do two things.  One, Decrease the spark rise time when the arc is established, in effect lowering the frequency and amplitude of radiated emissions off the unshielded ignition wires.  And two, lowers the spark event current commensurate with the total loop resistance of the coil, plug, and cap for two cylinders.  The later reduced spark current would also reduce electrode erosion extending the plug life assuming the carbs are delivering proper tune.

The plug heat range does matter also for plug life, with hotter plugs wearing faster than colder plugs, again given proper carb tune.  Generally speaking, hotter plugs last longer with higher ignition loop resistance.  It’s a combination of heat plus EDM effects of the spark leaping off the electrodes.

[Deltarider]

One point of curious confusion that I have regarding ignition resistance is that the CB650 came with both resistor plugs AND resistor caps, totaling 10k resistance per cylinder and 20k resistance per ignition coil. Some of the other bikes at the time had the same setup, but not at all. The CBX for example had resistor caps but non-resistor plugs, but the CB900 had both components with 5k resistors. [...]

Yes, but the bikes you mention are of an newer generation. They have more sophisticated carbs and run considerably leaner than the older CB Fours. But... I don't know if that has anyting to do with. When a second R plug gave up all of a sudden, I decided to return to standard plugs and resistor plugcaps again. This implied I had to abandon the silicon Dynatek caps which don't have a resistor built in. I wasn't happy with them anyway. I love silicone but they didn't offer the firm connection NGK caps do. In the past I've communicated more than once why I was not happy with the generic Dyna coils. Recently I discovered another disadvantage. To address their primary connections coming loose (vibrations) causing intermittent misfires, I decided to add spring washers. Now there's not much room there for your fingers to fiddle with tiny screws and washers. If you drop one, it will most likely end up where the sparkplug sits and then... it's time to go fishing.
OEM coils may be costly, but they're a direct fit, plug and play, so to speak, with excellent connectors which shield well against moisture. All in all the Dyna coils proved less reliable on all fronts.

[rotortiller]

Here is some information from the horse's mouth.  http://www.ngkntk.com.br/site_ingles/direct/p8.html

[fizzlebottom]

In practice I noticed they stayed cleaner longer than the non-resistor plugs and tried some in my own 750. I discovered they required the mainjets be leaner (105 instead of 110 size) to stay clean. Interestingly enough, so did Honda: the K4 came with the 105 mainjets, too, as did all the later 750s.

See, that's kind of similar to one of the only differences between the carbs that came on various '81 & '82 CB650 models (aside from press-in vs screw-in slow jets). Mains on all '81 & non-Nighthawk '82 models were 120, whereas mains in the '82 Nighthawk were 118. I wonder if they made that change for some combination of pressure from the EPA to run leaner and feedback that plugs weren't lasting long enough.

[Don R]

  Caution, old guy story to follow,
 A little background, in the 50's it was realized the best way to find a metropolitan area with a missile was to follow the RF noise made by all of the cars.
 My brother had a 55 chevy with solid core wires and Raja plug terminals, our old antenna TV would roll lines through the picture when he got within two blocks of home. Mom never figured out how I could predict his arrival.
 Later on, he got a studebaker ac delco rotor that had a built-in resistor so he could hear his own radio.

[HondaMan]

  Caution, old guy story to follow,
 A little background, in the 50's it was realized the best way to find a metropolitan area with a missile was to follow the RF noise made by all of the cars.
 My brother had a 55 chevy with solid core wires and Raja plug terminals, our old antenna TV would roll lines through the picture when he got within two blocks of home. Mom never figured out how I could predict his arrival.
 Later on, he got a studebaker ac delco rotor that had a built-in resistor so he could hear his own radio.

Yep, I made extra $$ in high school by "quieting" the old Volkswagen, Audi (Porsche, actually), Chevy II and Falcon radios by installing resistor spark wires (and sometimes also plugs) in other folk's cars. They were jealous of how nice my AM radio worked in my '63 Galaxie...

[Alan F.]

I enjoy the stories, someone should start that thread.

[willbird]

I bought a set of 4 Genuine Honda from JTmarks on Ebay April 24th.

The two part numbers are
30700-GAR-000
30700-MW3-000

Glad now that I got them when I did.

Everett Powersports still has them listed for the same price. Mine are marked NGK.

[grcamna2]

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