Spark plugs & caps

[Giblet]

Changed plugs in my GS1100GK last night to try to correct a very, very slight miss w/o a test run after. Have some minor oil fouling (smooth black, not fluffy) on 1 & 2. Installed an old set (NGK B8ES) I had cleaned & re-gapped earlier. Bike misses and cuts out on acceleration now. How often can plugs be cleaned & reused? Also wondering about the "caps" that go on the wires to the plugs. Is there a test for those & do thay ever go bad? Assuming they perform a resistor function since the plugs are the non-resistor type? Will re-install the set I removed last night first to see if it goes back to the same running condition as yesterday.Getting a new set of plugs tonight & will reterminate the caps if the problem persists. Coils are less than 2 years old. Bike is just shy of 30K miles.

[IanFrancisco]

As far as I know the only reason resistor plugs were ever invented was to reduce the static in AM car radios caused by the ignition. About as useful as mammaries on a bull on our bikes, maybe if we rode two-wheel Cadillacs like an ST1300... The caps perform no resistor function that I know of.

Test for spark the usual way by holding a plug (by the cap!) to the motor to ground it and crank. A fat blue spark indicates healthy coils/ignitor. If you see weak spark or get shocked, time to go over the harness/coil/ignitor connections and clean/solder/ensure good connections.

[redliner1973]

The caps are 5K resisitors used to supress RFI. they can be measured by untwisting them from tehe wires and using an Ohm meter. any more than 5-6k, chuck them and replace them. they are cheap, and readily available at most bike shops.

AS for plugs, it depends on how you cleaned them. If you used a wire brush, this can create tiny 'scratches' on the porcelon, and create carbon tracks that will drown out a spark, as it tries to use the tracks as a quicker path to ground.

My bet is that your caps are old and exceed the max ohms.

[IanFrancisco]

Guess I was wrong... Sorry for any misinfo!

[Giblet]

Guess we don't want to annoy the cagers!

OK, this is too funny to not tell. Went ahead and bought new plugs on the way home. First plug I pulled was one of the old ones, fouled and dropped on the electrode so there was almost no gap . Must have picked it up by mistake :roll: . Maybe dad was right, I would absolutely amazing if I just paid attention. Will check those caps this weekend. They are 23 years old after all. Any idea how long they shoud last? Like I said, the bike is just shy of 30K miles? No problem on the info. I thought I had been told they were resistors at some point but . . . . . "If, I only had a brain".

[Redman]

Hello Steve,

Yah, those caps can go bad. They can increase in resistance (well above the 5K) over time and miles and cause ignition problems. My experince is that they are the most likley item in the ignition system to fail/degrade over time (well, other than the plugs themselves). Sounds like you know that they are about $5 a piece, easy to replace, and 1&4 are differernt shape than 2&3.

Some people will recommend to always cut off a small length of the wire to get to new conductors when reconnecting the caps, but if you did that 3 - 4 times over the course of 10-15 years they would be too short, so I just inspect the conductors, maybe trim off 1/4th inch only if looks suspect.

So, hows it going now?

[Giblet]

Buddy!

Hey Dave! How's it goin in the "frozen waste lands of the north"? Hopefully the snow is all gone now. Forgot to mention the GK is running like a scalded cat 8O again with the new plugs. I'm going to call a M/C parts & service shop tomorrow and see what caps cost. New ones can't hurt. Looks like they are about $15 on Bikebandit. I'm my own worst enemy when it comes to the bike. I just need to pay attention.

Drive train, charging system, carbs, ALL good. Added some LED's Leon gave me and I think I'm ready for the 3's this time. Will PM you with further info.

[focus frenzy]

there is a resister in the cap, in the plug end of the cap you can unscrew the plug clip and it and the resistor will come out.
I just finished (at 2AM this morning!) installing Dyna coils and the instructions stated that resistor caps (or you could use resistor plugs) are needed for electronic ignitions as the RF energy can interfere with the electronic ignition control box.

I picked up Accel 8.8mm RF suppression wire set.

[SqDancerLynn1]

with the stock wires Use NGK plug caps VB05F & XB05F

[Giblet]

there is a resister in the cap, in the plug end of the cap you can unscrew the plug clip and it and the resistor will come out.
I just finished (at 2AM this morning!) installing Dyna coils and the instructions stated that resistor caps (or you could use resistor plugs) are needed for electronic ignitions as the RF energy can interfere with the electronic ignition control box.

I picked up Accel 8.8mm RF suppression wire set.

Wondered what those slots were for. May have 5-7K resistors here at work. Will go bug my electrical counter parts. Is it a standard ceramic/thru hole resistor or a surface mout package? Since I bought stock coils they came with wires attached. Used my old caps. Thanks SqDancerLynn1. I'll call around and see if I can locate them.

[SqDancerLynn1]

there is a resister in the cap, in the plug end of the cap you can unscrew the plug clip and it and the resistor will come out.
I just finished (at 2AM this morning!) installing Dyna coils and the instructions stated that resistor caps (or you could use resistor plugs) are needed for electronic ignitions as the RF energy can interfere with the electronic ignition control box.

I picked up Accel 8.8mm RF suppression wire set.

You use the resistor caps ONLY if you are using the stock solid core wire
If you are using aftermarket suppression wires you use a standard non resistor plug cap-- reg auto plugs

[Anonymous]

I think it's what you call a "thru-hole." I heard it called "monolithic" - it's just a little cylinder, no wires on it or anything, and it just gets squeezed on the ends by the plug apparatus.

On my 82 GS1100GK, I just had the same problem. I did a bunch of work on the coils and wires, and while things got better when I lost the resistors (did some ugly but effective splicing of graphite plug wires), the real problem was in the connectors for the coil primaries.

If you already know, skip this: There are two coils in each coil, a primary and secondary. The primary is where the current goes first, and the secondary is where it goes, well, second. The primary gets charged, and creates a standing field. The ignitor box grounds out the primary, causing the flux to collapse, which generates voltage in the secondary (which is coiled around the primary). Thus, 12V, through many windings, is converted to 20kV.

My bike had been missing consistently, but after the boot/wire work, it only missed when leaning to the left (yeah I know, it sounds ridiculous but it's true). Somewhere in the back of my mind was the voice of one of those old, wizened men on this forum who would always say, "Check all your connectors," and of course I'd never listen. But after a blown stator, a shot regulator, and then an engine misfire that turned out to be just a dirty, loose connector on the coil primary, I finally listened.

My suggestion to you is to check all the connectors, at least on the ignition circuit.

[Giblet]

I squeezed the connectors on the coil to tighten them up when I changed the coils about a year ago. Planning to run new & 1 ga larger wires in that circuit shortly. Gradually getting to everything on it. This bike sat up for several years before I got it so I have been chasing gremlins for a while. The end is near I'm sure. All is well now. This time it was the mechanics fault. Hopefully someone will read this thread and get some useful info out of it. Flying ta San Antonio to pick up an 04 Intruder (1400) tonight that I will have use of for several months. Hopefully progress will get faster. 8) Thanks guys!

[Redman]

I recall the caps being 5-6 bucks apiece, but that was a gew years ago, and my memory is not that reliable. But sounds like you found the problem to be other than the caps in this case.

Snow up here was gone about 3 weeks after the Texas Hill Country ride. BUt I still have the pictures ready to show anybody that asks about the T-Shirt.

So you get the GK running like it should, and now you are getting a fairly NEW cruiser bike. You said you "have use of it" for a few months. Sounds interesting.

Catch you guys later, I'll be gone for a week long bike trip (although in this case "bike" means bicycle.)

[Giblet]

Actually I'll have it more like 3 to 5 years but who's counting 8) ? May just buy it in the spring. Nice bike but the GK beats it hands down (more comfortable) for long distance trips. Had 415 miles on it when I left New Braunfels this AM. Just shy of 700 now. Yep, I'd say thats fairly new. Have a great time Dave & BE SAFE. I remember Michigan being beautiful this time of year. Still gonna look at the caps though.