PLUG CAP RESISTOR REMOVAL/REPLACEMENT

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PLUG CAP RESISTOR REMOVAL/REPLACEMENT

Postby LRCXed » Sun Aug 10, 2008 6:53 pm

If you want to bypass the work below just buy a set of none resistor spark plugs from Wemoto UK(Ship International and are a trusted supplier),

http://www.wemoto.com/bikes/honda/cx_500_a/79-80/

And use NGK DR8 ES-L Resistor Spark plugs as per,

http://www.pdsrecording.site90.com/cxgl500/Plugs.htm


I have used the above for over 8 years.




Image

Picture Courtesy of Don(Blindstitch)


Note:Even one bad spark plug.One bad Plug cap or one bad HT Coil lead/Damaged or missing Air-dam or Bad coil can stop the engine under load from revving above around 5,000 Rpm/60 Mph Approx.Also see this thread,
http://globalcxglvtwins.hostingdelivere ... f=10&t=335
For cheap CDI coil replacements(not Transistor Ignition Coils)




Using a Digital Multimeter on a 20k setting a Resistor Spark plug should have a reading of around 7.5k(7,500 ohms) between the brass plug holder and the Ignition Wire screw.



On the USA based CX?GL bikes, there is a resistor inside the spark plug cap that can cause a lot of problems with the ignition system and the strength of the spark delivered to the spark plug. There is a simple cure for this. Remove all the internal components inside the cap and change out the resistor and the aluminum rod with a length of brass or aluminum rod equal to the length of the 2 parts combined. This is a good process to also just check to see if you have a lot of corrosion inside the assembly also. It can cause a high resistance in the delivery of the spark, and should be cleaned well if you do not want to change out the rods as shown below.
I have been running these brass rods for about 4 years now, and have had no issues at all. It works.

Inside the tip you will see a the brass end that clips onto the plug. It's threaded into the cap itself and will need to be removed.
Image

Make sure you use a wide flat blade screw driver that is also thick enough to make good contact in the slot so it does not slip and round off the brass slot.

Image

When you get the threaded cap out you will find the resistor, an aluminum rod, and the tension spring under it, in that order.

Image

Notice in this picture the dark colored resistor. This one came out of a cap that had a lot of corrosion inside it, and was causing a lot of heat and resistance in it. This is a good sign there was a problem with how the bike ran.

Now for the cure. The brass rod is the replacement for the resistor inside the cap. It is the total length of the 2 combined. The total length of the brass rod is 2" .170 thousandths, and the diameter is .190 thousandths. I used a section of brass welding rod I got from a welding supply shop. You can use aluminum rod also. Before you put these parts back in, make sure you clean out the inside very well. I used a long thin flat screw driver and twisted and cleaned out the contact until I could see clean metal inside it so the spring makes good contact, as well as a thin brass bottle brush to remove all the corrosion. Use a good electric contact grease or a battery anti corrosion compound found at most auto parts stores when you reassemble it.

Image

If you have a rod that is stuck inside, as a lot of them are, due to corrosion, you can drill it out if you have the right equipment. I used a 1/8" drill bit with tape built up on it so it stayed centered and drilled a hole down the center of it. Followed with a long 1/8th bit to get it all the way through until I felt it go through the end and into the spring area. Be ready to stop when you get near the end so you don't mess up the spring. Now I followed it up with a drill bit of 13/64th or a #4, .208 thousandths, to drill out the remainder of the aluminum from the inside of the cap. Make sure you keep it centered so it does not mess up the threads where the brass clip cap threads into. Be careful also, to make sure you keep it centered so it does not angle off and drill out the plastic cap. This worked very well for me while I was getting a cap ready for Blindstitch. He has been waiting patiently for a set to replace his bad caps.

Image

This is the pile left from drilling out the stuck rod from all the corrosion that had it stuck inside.

Image

Be careful and take care to clean all the components well, and you will have a good solid spark delivery to your plugs.
Hope this helps you out and cures a bit of your ignition issues.
Larry
"If I need to have someone do something for me, why shouldn't I learn to do it myself"
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Re: PLUG CAP RESISTORS

Postby kingston73 » Tue Nov 11, 2008 3:00 am

I asked this on CC site, but I'd like to ask all y'all here as well.

Like Blindstitch found, my 2 '79 coils had the 3 pieces (spring, rod, resistor) but my 2 '81 coils that I've been using have the long spring, resistor only. I cut 2 longer rods to replace the rod/resistor and 2 short, resistor sized rods to use with the long springs. Also, the end caps, the ones with the screw slots, are different. The one set has a flat end, the other set has a cupped end. Anybody know if there's any advantage of one over the other? I wonder why honda changed the makeup of them?
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Re: PLUG CAP RESISTORS

Postby Gman » Tue Nov 11, 2008 10:08 pm

kingston73 wrote:I asked this on CC site, but I'd like to ask all y'all here as well.

Like Blindstitch found, my 2 '79 coils had the 3 pieces (spring, rod, resistor) but my 2 '81 coils that I've been using have the long spring, resistor only. I cut 2 longer rods to replace the rod/resistor and 2 short, resistor sized rods to use with the long springs. Also, the end caps, the ones with the screw slots, are different. The one set has a flat end, the other set has a cupped end. Anybody know if there's any advantage of one over the other? I wonder why honda changed the makeup of them?


Sorry I can't help as they never fitted these plug caps to the UK/European models .
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Re: PLUG CAP RESISTORS

Postby H-glenn » Sun Nov 16, 2008 8:35 pm

Found a source of 3/16" solid brass rod in the US at Hobbytown hobby stores. They have a rack of round, square tubing and well as
solid round stock 1 foot long. I don't have a micrometer but the brass rod is just slightly smaller then the original
aluminum rod. Bought it for $2.09. Didnt find it online at their website so I called a nearby location.
Its what I'm going to use and I wondered about using a dab of
conducting grease at each point of contact inside the plug cap when reassembling.
That's conducting grease, like "Noalox" not dielectric grease which is a non-conductor.
MY concern is the high temp of the head area would cause the grease to seep/ flow down the plug cap
and down the plug. Any thoughts on this. :?:
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Re: PLUG CAP RESISTORS

Postby I'm going to GL » Mon Nov 17, 2008 4:01 am

Welcome aboard H-glenn,

IMO, using the proper grease shouldn't hurt anything, even if it were to melt down onto the plug. If anything, the melting scenario would seem to make the boot/plug more resistant to moisture and should make the boot easier to remove from the plug when servicing.
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Re: PLUG CAP RESISTOR REMOVAL/REPLACEMENT

Postby quicksilver » Thu Sep 03, 2009 11:47 pm

Hey guys. I was wondering if using steel rods or cut off bolts would be OK or would it cause a problem. Thanks...Ken
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Re: PLUG CAP RESISTOR REMOVAL/REPLACEMENT

Postby Gman » Fri Sep 04, 2009 8:41 am

I don't think it would give much problem but being ferrous they would be more prone to corrosion,rust.You can use the shank off a cheap brass screw from a Hardware store.
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Re: PLUG CAP RESISTOR REMOVAL/REPLACEMENT

Postby quicksilver » Fri Sep 04, 2009 9:24 am

Thanks for the reply Sheppola. I cut some steel bolts at work and will use them until I get some brass ones. I am only just in the restoration stage. I have cleaned the carbs and had it turning over. It has not fired yet. I am still working on tracking down the electrics.Thanks...Ken
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Re: PLUG CAP RESISTOR REMOVAL/REPLACEMENT

Postby Rayman » Sat Sep 05, 2009 12:35 am

Ideally if removing the resistors from the plug caps you should change to plugs with integral resistors.

reving the resistors altogether doesnt seem to have any adverse effects from what I've seen - but the reason for the resistor
is to slow down the front edge of the spark -
this cuts down the radio interference -
but you say - i dont have a radio and if it causes noise for the cages next to me - who cares ;).

BUT
the generated RF noise can find its way back into the sensor coils of the ignition system - and cause misfiring as a result.
your right cylinder firing could cause the left to go off at the wrong time etc -

There is filtering on the inputs of the CDI unit that cuts a lot of it out, not to sure one the TAI versions as its all sealed up.

something to think about - they are there for a reason -
other option is to replace with resistive leads but they are a nuisance to get to connect to the spikes properly -

Something to think about anyway.
YMMV

Regards
Rayman
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Re: PLUG CAP RESISTOR REMOVAL/REPLACEMENT

Postby Gman » Sat Sep 05, 2009 12:49 am

Some of the UK CDI Cxs didn't come fitted with the plug cap resistors(I've just bought and fitted a pair funnily enough) and use the same CDI coils and I suspect the CDI box.
I think the resistors were another import limitation placed on the American versions.
Remember also that AM radio was the main radio source in that time,then came FM which is less susceptible to Radio interference and now of course here in the UK we have DAB(Digital Audio Broadcast).

Note.The resistors have an impedance of around 7.5k (20,000 ohm meter setting).
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