Topic: NGK Spark Plugs with Smaller Wrench Hex Size

[pekingduck]

I use projected tip NGKs, such as DPR7EA-9 or DPR8EA-9 in my CB650 and Benelli Sei, and have always had a little difficulty getting a plug wrench in, especially next to the tach drive. All SOHCs use "D" plugs that use an 18mm hex plug socket.

I found that NGK makes the exact same plugs except with a smaller 16mm hex socket size, DCPR7E and DCPR8E.  Now 2mm smaller may not sound like much, but it makes a world of difference when installing them, the socket now rattling around.

[Deltarider]

Why do you run other sparkplugs than standard? I don't have a problem with fitting sparkplugs. The wrench in the Honda tool kit is well designed for the job.

[PeWe]

Same with CB750, the Honda original plug socket tool to be used.
Fits well in the jacket pocket too.

[Little_Phil]

Presume DCP7E and DCP8E also available if you want non resistor plugs which most do.

[fizzlebottom]

Interesting. I'm comparing the OE-recommended NGK DR8ES-L and the DCPR8E, and they seem functionally equivalent. The terminals are different so I'm not sure if you'd need some different type of plug cap. That 16mm plug might also be a different heat range, and the electrode is a slightly different style but overall reach is the same between the two.

That #3 plug can be a real bear to get to with anything but the original Honda plug wrench. So if you don't have the original toolkit and can't get hold of one, then this might be an interesting way to make your life a little easier.

[HondaMan]

Now that's a cool find! The CB650 plugs are a real PITA to change, even with the OEM Honda tapered-top sparkplug (toolkit) wrench. They are near impossible to change without it, too. I used 2 different sockets to change the plugs on a CB650 (multiple times) that was just here, fouling plugs from screwed-up carbs.

The "R" plugs will help, too, when the coils get replaced with those no-resistor plug boots that seem to be popular on those bikes. The electronic triggers that run its CDI (yes, it is CDI...) need those special 2.4 ohm coils, and they don't seem to be available outside OEM unless you get the ones with molded-on sparkplug boots and no resistors.

[Deltarider]

Why do you run other sparkplugs than standard?[...]

Maybe I didn't phrase my question right. I'm curious why you prefer 'P  -9' over the standard sparkplugs.

[fizzlebottom]

The electronic triggers that run its CDI (yes, it is CDI...) need those special 2.4 ohm coils, and they don't seem to be available outside OEM unless you get the ones with molded-on sparkplug boots and no resistors.

Now this is interesting, because just about every source I have read, including the FSM, says that the CB650 uses a transistorized pointless ignition (TPI) and not a CDI. The CB450SC Nighthawk, on the other hand, actually does have a CDI ignition and it is called out as such on the parts lists. The CB650 ignition is functionally identical to many of the Honda DOHC/4 and CBX models around the same era, and they're all similarly described as "Transistorized pointless ignition" from what I've seen.

[pekingduck]

Don't think the DC plugs are available in non-resistor.  These DC series plugs are used on some newer Harleys, KTMs, and watercraft, and likely more.

I use projected tip plugs because they seem to work at least as well as the older D7ES/D7EA and D8ES/D8EA  that were specified as new.  Projected tips were not in common use when the bikes were designed, but they are pretty much standard on all bikes now.


I use a stock tool kit plug socket with a 3/8" drive socket welded to the top, and it works fine, but the smaller socket size just makes it a little easier, and offers more choices. The 16mm size plug is the same as used on many smaller Hondas, like Groms and 2-valve CRFs.

[HondaMan]

The electronic triggers that run its CDI (yes, it is CDI...) need those special 2.4 ohm coils, and they don't seem to be available outside OEM unless you get the ones with molded-on sparkplug boots and no resistors.

Now this is interesting, because just about every source I have read, including the FSM, says that the CB650 uses a transistorized pointless ignition (TPI) and not a CDI. The CB450SC Nighthawk, on the other hand, actually does have a CDI ignition and it is called out as such on the parts lists. The CB650 ignition is functionally identical to many of the Honda DOHC/4 and CBX models around the same era, and they're all similarly described as "Transistorized pointless ignition" from what I've seen.

Yep, that's what I'd heard for years, too. Then I saw a schematic of one. They are a CDI. They are called 'pointless ignitions' because they are, truly, pointless, but they fire the coils with a single pulse, not a field-collapse as in points-based Kettering systems.

The big-deal difference: since the 1960s when they were first created, the "CDI" systems were the giant spark machines (12" square by 8" tall) that raked in [literally] millions of $$ for extremely overpriced units, some of which could consume up to 50 amps of 12 volt power to make...a spark or two, or 3, or even 5 or 6. The trend then became to call them either "multi-spark CDI" or just "CDI" systems.

The CB650's circuit schematic (which is also the same device used on other later bikes) discharges a capacitor into a low-ohms coil for a spark. That is the definition of Capacitive Discharge Ignition as it was first invented. The others should normally be called "multispark systems", but often are not.

[fizzlebottom]

Yep, that's what I'd heard for years, too. Then I saw a schematic of one. They are a CDI. They are called 'pointless ignitions' because they are, truly, pointless, but they fire the coils with a single pulse, not a field-collapse as in points-based Kettering systems.

The big-deal difference: since the 1960s when they were first created, the "CDI" systems were the giant spark machines (12" square by 8" tall) that raked in [literally] millions of $$ for extremely overpriced units, some of which could consume up to 50 amps of 12 volt power to make...a spark or two, or 3, or even 5 or 6. The trend then became to call them either "multi-spark CDI" or just "CDI" systems.

The CB650's circuit schematic (which is also the same device used on other later bikes) discharges a capacitor into a low-ohms coil for a spark. That is the definition of Capacitive Discharge Ignition as it was first invented. The others should normally be called "multispark systems", but often are not.

Mighty interesting. None of it really changes how I'll go about working on or riding mine, but I suppose I can now refer to it as a CDI ignition instead of TCI or TDI or whatever other acronym I was used to using.

[Deltarider]

[...]
I use projected tip plugs because they seem to work at least as well as the older D7ES/D7EA and D8ES/D8EA  that were specified as new.  Projected tips were not in common use when the bikes were designed, but they are pretty much standard on all bikes now. [...]

I have thought about this. The reason I didn't do it, is because of the story I heard about an owner of IIRC a Suzuki GSX400F. He was racing down the German Autobahn, forgot to switch the petcock to reserve in time and ended up with 4 holes in his piston crowns.
Now in the past, I myself have been cruising on German Autobahns at 140 km/h, just to keep up with local traffic and quite a few times, I also was late, because of the increased fuel consumption, switching to reserve. I can understand an even further projected tip can be good, but I never dared to go there.

[rotortiller]

I found that NGK makes the exact same plugs except with a smaller 16mm hex socket size, DCPR7E and DCPR8E.  Now 2mm smaller may not sound like much, but it makes a world of difference when installing them, the socket now rattling around.

That seems like a good reason.

Re the CDI thing, it's different from a pointless transistor system as it typically discharges a large capacitor into the coil, typically over 200 volts. Also uses different coils for this. It is available in both a DC and AC version, one needs a battery while the other does not. The latter AC type is sometimes termed a magneto CDI being an electrically self-contained independent ignition system. Examples would be 2T dirtbikes and Kawasaki H2s. The main advantage is more energy or a very bright hot spark which puts an end to fouled plugs under normal conditions. They can be very reliable, lasting over 50 years. Don't be fooled as many electronic ignition systems use the CDI term incorrectly, remember even a points system has a capacitor lol.

[Deltarider]

[...] or a very bright hot spark which puts an end to fouled plugs under normal conditions. [...]

I wouldn't make the conclusion it 'puts an end to fouled plugs'. It may help, but it's not one follows the other.

[Little_Phil]

Non R DCP7E type:
https://www.sparkplugs.co.uk/ngk-spark-plug-dcp7e-2363-2
I have D7EA:
https://www.sparkplugs.co.uk/ngk-spark-plug-d7ea-7912-2
Spot the differences.

[rotortiller]

I wouldn't make the conclusion it 'puts an end to fouled plugs'. It may help, but it's not one follows the other

I would not make any conclusion if I were you as I doubt you even have a two stroke let alone ride one on a regular basis. And please do not take me out of context with your cherry picking. I said it puts an end to fouled plugs under normal conditions, anything can be fouled, even a four stroke in the wrong hands with unsuitable parts and/or settings.

[Deltarider]

[...] And please do not take me out of context with your cherry picking. I said it puts an end to fouled plugs under normal conditions, anything can be fouled, even a four stroke in the wrong hands with unsuitable parts and/or settings.

No cherry picking. For the record. I've quoted your original contribution correctly in reply #13. I have noticed just now that you have reedited your original reply... And just now in your last reply (#15) you have added: anything can be fouled, even a four stroke in the wrong hands with unsuitable parts and/or settings.
Moreover, please note that whenever I leave something out of a quote, because it's less or not relevant, I indicate this with [...] and [...]. so readers that are nonetheless curious of what else was said in between that [...] and [...], are invited to go to the original post. May I put it to you that so far I'm the only member here that practises this courtesy? 

[rotortiller]

Yea I added or edited in  'electrically' to 'self contained' since it often has more than one component in different locals. Tried to make the post dick proof. I did this because I know guys like you are available in wait.

[Deltarider]

Yea I added or edited in  'electrically' to 'self contained' since it often has more than one component in different locals. Tried to make the post dick proof. I did this because I know guys like you are available in wait.

Well, good I'm here.

[rotortiller]