compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
by Hombre sin Nombre & Kristian #562
Adrian Jowett's Excellent F650 site was the first site to mention that the Plug Caps/Coil Wires/Coils can fail.
So what does he mean by fail.? Well they generally donít suddenly stop working, they just build up resistance to the point where you spark gets weak and things donít work like they used to.
The symptoms of Plug Caps/Coil Wires/Coil failure are poor starting, some mid range lag and possibly Poor Gas Mileage. Adrian noted that this didn't distinguish between the three, but you CAN test each of them and isolate which one it is.
Note that Starting and Running Problems can also be a rectifier going bad, which is covered in the Voltage Rectifier FAQ. If your bike has problems not wanting to rev over 1500 rpm when cold, try that FAQ first.
According to the Manual, secondary coil
(plug lead to ground) resistance is 6-13k ohms. If you have one at 3k ohms, it
may be the plug cap (Check this FIRST) OR the coil is
going bad and should be replaced. They DO go bad - moisture can get in thru a
microscopic crack, etc. Eventually, if the resistance drops too low (short), it
may drain power from the good coil - if you are not having ignition problems
yet, you may soon, as the 3k coil is probably not firing. Not sure if a dead
short will damage the $300 CDI box, but you don't want to find out. If I were
traveling across Africa with no spares, I'd disconnect the bad coil input (12v)
wire (NOT the plug lead!) to make it back. I would not run with just one coil
unless forced to. You might want to see if you get any spark from that coil.
Note: Primary coil resistance (12v terminal - (Orange Wire) to ground) is supposed to be .2-.5 ohms.
Many Chain Gang Members have discovered that their Poor Starting or Low Power problem lies in the OEM Beru Plug Caps resistors going bad and have gained an instant (the most gratifying kind) fix by simply replacing the Spark Plug caps. Adrian Jowett's site mentions they should possibly be replaced after 5 years as a matter of course.
The bike will run with a bad plug, as one of the OEM Beru (1k ohm) plug caps has been tested at 50k ohms, on a running bike!
If you don't want to test it, want to take a punt on this being your problem (most unscientific) and think yours are about due for replacement anyway, you can simply purchase a New Spark Plug Cap.
The stock Beru caps can be rebuilt. Sometimes even caps that are working and don't look corroded have tarnish on both ends of the resistor and will not provide a solid 1k Ohm reading until shined up with emery paper. The corroded caps have a wasted resistor and battery terminal type corrosion on the aluminium spacer and the spring. A little water and a little salt will wreck them. If you have the stock caps it would not hurt to take them apart and check them, especially if you ride in the rain or park near an ocean. Very often the corroded cap will be the outside cap.
The OEM Beru Caps are rated at 1kohm resistance, however no aftermarket supplier makes Caps with this resistance and neither you nor your bike will notice any difference between the 1kohm resistor and the 5kohm resistor. If you want to know more about why, see the Detailed Technical Explanation Section below. 5Kohms is supposed to be as good for the application, with better noise suppression (for e.g. for bike to bike radios). Note that the specified limit (with an OEM cap of only 1kohms) that you would expect to measure was 6-13kohms, but you have just installed a 5kohm spark plug cap, adding an additional resistance of 4kohms, so you should expect to find something more like 10-18kohms if measuring the coil circuit with the new cap installed.
NGK make a Cap (ref. # NGK XD05F, 102 degree, 5k ohm) which fits perfectly, is long enough to go down the Spark Plug Wells and has a nice shallow bend at the top, so the cable doesn't get any sharp kinks in it.
NGK also make a Cap ref. # NGK XD10F, 102 degree, 10k ohm version of the above which will work, but the 5kohm is highly recommended over the 5kohm cap. NGK also make short 90 degree bend 5kohm caps, which will also work, at a pinch, but don't fit very well in the Plug Wells at all. NGK also make Long Straight Caps (ref. # NGK SD05F), however these don't leave much room for the Plug Coil Wires under the tank and they have to be bent at a bit of an angle to fit, which is not recommended.
As noted below, repairing the OEM Beru Caps by replacing the 1 kohm resistor or replacing the OEM Beru Caps entirely appears to give better results than using aftermarket caps with higher resistances.
For more Technical Details about the Plug Caps, see the section below.
Which Spark Plug Lead goes where?
Q. While I had the bike in bits I did some other maintenance and now have a really silly question. Which spark plug wire goes to which plug on the Classic? And what happens if you get it wrong? I
A1. Any!. And what happens if you get it wrong? Nothing ! If you get them on the correct plug they "sit" better that's all. Why not. They both fire at the same time!. It's single cylinder, silly. Mal
A2. Mal is correct, but actually the short one is closest to the RHS. Think Right-Right, Left-Left. These were my replacement NGK leads. NGK Plug Leads.
Replacing the Spark Plug Caps:
Repairing the Old Plug Caps:
Rebuild#1 Replacing the Resistor
Note that if the problem lies in one of your Coil Wires, or the Coil itself, then of course just replacing the Plug Cap won't fix your problem.
UPDATE - Sources of the Resistors:
1. Canadian Tire
here in Canada has 1kohm Resistor Caps, they are the NGK LB01EP (says 1Kohm on
the Side) - Cut them open with a hacksaw. The reason I so brutally
hack-sawed them is because they are a 90 degree cap and the resistor is behind
the 'wood screw' end, not at the spark plug end where you can just undo the
brass cap. There is no way to get to the resistor without destroying the cap.
Thanks to RacerRoo. Note the FAQ describes how you can work the "wood screw"
out quite easily. Just pops right out if you work it a few times with a
2. http://www.800-airstar.com/ign.htm also shows 1kohm Caps are available. Thanks to Mason #631
If you actually want to test your existing caps you will need a resistance tester, commonly called an Ohmmeter, or VOM (Voltage/Ohmmeter), sometimes a DVM (Digital Voltmeter). Almost any common cheap VOM will work for this, as long as it has a suitable (resistance) Ohms scale. You can spend $20-$50 dollars for something perfectly suitable for general use, or $100's of dollars for something fancy. See Testing - Oooh Electrical Stuff, I don't know anything about that.
Beru Spark Plug
Cap Rebuild: #2 Bypassing the Resistor
by Pete in Oz
As promised, here are the detailed instructions
for a rebuild of the Beru caps. It's a little late because after a week and a
half the bike wasn't running quite as well. After metering one of the plug-caps
to ground I had one open circuit. When I pulled everything apart, I found I had
two problems, first the Beru cap was open circuit internally somewhere in the
top end (I gave up on it and threw it out at that point), second, I'd nicked
(small cut) the HT lead which had broken near the coil end. Rebuilding with an
NGK cap and the bike runs well again.
This should only be of interest to owners of older bikes, plug cap problems seem reasonably common after a few years and make the bike run badly rather than not at all. The performance difference is pretty dramatic, but that's mainly just from fixing the HT problems rather than some magic associated with how I did it.
One thing you do need is a screwdriver with the right sized blade to unscrew the old Beru cap.
You also need a hobby knife and some small scissors, and I'd recommend some neutral cure silicone sealer. There's some assembly required.
Inductive leads. Apart from having inductive written on them, the leads are fairly easy to identify, there's an outer (black plastic) sheath, fibreglass braid (string) under that, an inner Teflon insulator (white) then a ferrite core (black, hard & brittle) with very fine wire wound around it. Note: The Bosch inductive lead I used is about 5kohm/m, so the 12 length used is around 2k which makes up for the missing cap resistor. Eventually I'll track down a 0 ohm plug cap and replace the NGK.
The bad news is: The inductive leads I got were fatter than the originals, that meant that while they screw into the cap end, you have to trim off the outer sheath and braid to get them to screw into the coil. That's fairly tough to do, if you nick the inner sheath, it'll split when you try to screw it into the cap or coil.
You need some brass rod. I got mine from the local hardware store, it was actually threaded brass 1/4 rod intended for making up odd length brass screws. (~$4.50AU). Cutting down a 2x1/4 brass machine screw will work as well. (See below for how to get the length right). So will heavy (1/4) copper wire. You could even use a nail, problem is a nail will probably rust. If you bypass the resistor, you should replace your leads with inductive (resistor) wire leads. Or you can run a resistor plug. There's supposed to be an additional 1k (or maybe 5k) ohms somewhere between the coil and the plug. The OEM resistor dimensions are: 1. Measured with a ruler---about 1 3/16" long and 3/16 inch in diameter. 2. Measured with a dial caliper (if I am reading it correctly) 1.185 inch long and .175 inch in diameter. Colorado Bob
Note the following: If the coil is supposed to be within the range of 6-13k ohms and the cap is 1k ohm, and the coil is actually 9k ohms, and you jumper the cap as in this method, you get 9k ohms. If you add a 1k ohm cap, it's all now 10k ohms. Both rebuilds #1 & #2 are within specs, but the resistor is in the wire lead to prevent electromagnetic feedback into the CDI unit. It's not just the total resistance of the coil that counts - the resistor (cap or wire or plug) is in the output end of the coil for a reason - suppression of voltage spikes and feedback. HsN
Rebuilding the Beru cap:
Spray some WD-40 down the Beru cap, leave it alone for an hour.
Unscrew the inside of the cap, you DO need the right size flat bladed screwdriver. The thing you are unscrewing is brass and quite soft.
Once you've unwound it as much as you can, tap the cap on a hard surface to get the internal brass threaded do-hicky out.
are lucky, you'll also have the high voltage resistor, a stainless steel
spring and a lump of something fall out as well. If they don't, keep on
tapping. There are 4 bits in there. Mine were very corroded. The Blob is a
This picture is from an NGK Cap, but this is about what it all should look like:
blob spring resistor threaded cap (Screw)
You need all the bits.
Lay the blob and resistor end to end. That's the length of brass rod you need. The measurements are: 5-7mm diameter stock, either steel, brass, aluminium or some other conductive material. (quarter inch for you American Luddites), 37-40mm in length (inch and a half). Pop it in and it'll work. (from Shank).
Cut it to the right length. (I'd suggest having enough of whatever to make several attempts if necessary).
Next, get something, a long nail or a long small bladed screwdriver and try to scrape all the corroded crap out of the bottom of the plug cap. Give it a spray of WD-40 then mop it out with a Q-tip.
Make sure one end of your rod fits inside the threaded cap. You may need to file it down a little and also clean up the ends if your hack-sawing was as ugly as mine.
Clean up the spring, drop it back into the cap, drop the brass rod in, then put the cap back in. Tighten down. If you got it right, you'll feel the rod move a little against the spring if you push something down through the centre of the threaded cap.
Next, clean up the screw at the other end of the cap (where it goes into the lead). You can try metering it now (good luck), it SHOULD read 0 ohms, if it doesn't, the cap is probably totalled.
Preparing the leads:
The leads are 12 long, DON'T cut them to length yet. If you can, get an inductive lead long enough for several bike leads.
Take the tank off the bike, remove one of the coils. (You cannot do this in place). Unplug the cap, unscrew either the plug or coil end of the ignition lead and remove everything.
Stretch the old lead out, and make sure I was right on the length.
at one end of the new lead. If it has a cap on it from when you purchased it,
cut it off now. Move the coil end boot from the old lead to the new one.
(Assembly is one shot only). See if you got lucky, does the lead screw right
into the coil ?. If so, great, tighten it up, slip the boot on.
If not: get the hobby knife and roll it around the lead about half an inch from the end. You want to just cut through the outer sheath, nick the inner and it'll break off when you try to screw it into the coil. That's why you still have one long length of cable, you may need a couple of attempts at this.!
Trim off the braid with scissors, screw the cable into the coil, before you get to the end run silicone into the gap. It's HARD to screw in.
Push the rubber boot over.
Now, replace the coil on the frame, run the cable through the wire guide.
Also: Make SURE you put the electrical connector to the coil back on at this point. It's easy to forget.
Next, cut the lead to about 13, slip the cap end boot over, screw into the plug cap. You may need to do the trim thing here again, you may not. The extra inch doesn't make any real difference to fit, but gives you two shots at trimming it if you nick the core.
Slip the boot back over the Beru plug, plug onto the spark plug.
There should be enough fuel in the carbs for the bike to start. It's worth checking at this point.
If you are doing both leads, repeat the above. As before, make sure the bike still runs.
Replace tank/fairing fuel lead, tank vent hose.
Go for a ride- preferably starting in a direction that's uphill from your house :-). Go round the block a few times. Get enough courage to go for a decent ride in the hills.
Look down at the rev counter while pulling out of a tight uphill corner and note that you are pulling away smoothly from 2500RPM when you used to have to be a gear lower and above 3500rpm or you'd stutter.
NOTE: I would not install a jumper and operate the cap at less than 1k (nominal) resistance unless I were operating under emergency conditions. IMO, you put your CDI ignition computer at risk. YMMV. I do not suggest anyone run without any resistor unless they have resistor wires. You might run fine for years, and you might not. Don't be surprised if you eventually have CDI problems. Only time will tell. I sure hope you guys are right in omitting any resistance in the ground. I guess we'll know in a year or so. I may be wrong but the way I look at it is that installing resistance wire or a new cap is an easy repair for less than $5 . The CDI box costs about $200-$300 and can be difficult to diagnose (especially in intermittent operation), and is not repairable, nor returnable. It's your call. Todd #389.
Now about steel corroding faster than brass, I can't find brass stock. Corrosion with steel in cap. The problem is electrolytic effects, you have a tiny battery in there with the steel & brass. When I tried it the steel went pretty quickly and ate holes in the brass of the cap as well. 1/4 inch brass screws work just fine. Just cut the head off. WRT to the resistor/no resistor argument. The total resistance is spec'd at 6k-13k. Removing the resistor puts you at about 8.5k which is within the spec'd range. You may annoy people with CB's more :), but it shouldn't cause the CDI to fail. Of course, it's your $, and I'll admit I tracked down some "inductive" leads (Bosch car leads) which run to about 2k/foot to avoid any possibility of problems. That's a better fix for a number of reasons than a lot easier than trying to source those 1k resistors. I'd also agree with other comments: Dropping in NGK's caps works, but it isn't as good as removing the resistor. (You can remove the resistor from the NGK caps as well...). Pete
For now I put the bolt in and it works fine. Did this on the left plug only; the other one was OK. I even was able to turn the idle down from 1700-1800 to 1400-1500 like it is supposed to be, without it stalling. The ohm readings are perfectly centered. However, I pretty much believe the people who said it isn't good to run a jumper. To me that seems like putting a penny in an old home fuse box so the fuses don't keep blowing. Eventually the wires heat up and the house burns down. If I don't come up with a better solution fairly soon or if I don't hear back from "rakaD", I will get the NGK 4 or 5 ohm plug cap and see what happens. Colorado Bob.
Testing - Ouch Electrical Stuff, I don't know anything about that:
The old-fashioned way
The new-fangled way
Q. Electricity baffles me. I read the FAQs & I'm still confused. I measured the Ohms between the cap and the coil. Gangers have said it should be between 6 and 13 ohms with the stock caps. So, I assume that if it is lower than 6 then it is OK? One cap is 4.5 and the other is 5.5 ohms.
Q. I took my one plug cap apart that was reading too low a resistance. When measuring the resistance of the ceramic cartridge resistor, I got a reading of "0", as in zero. Is that bad? I couldn't tell from the FAQs, but assume it is bad. On Monday I am going to an electronics store that may have the resistor we need. Do I ask for a 1k ohm resistor? If I put it on my meter while in the store is it supposed to read about 1k ohm?
If you were to measure most types of 1k ohm resistors, it should show around 1k ohm (1000 ohms) or thereabouts on your meter, hopefully between 850 and 1150 ohms. 0 ohms is the same as the test leads shorted together, no resistance (except on the most lowest, most sensitive scale, where you are actually measuring the test leads). Overload (Old) should be when the leads are held apart, infinite resistance. Resistors for noise suppression usually run at 5k ohms and higher. Todd #389
The resistance in the plug is mainly to reduce radio interference, unless BMW has some diagnostic, (which would be a bit tricky), it shouldn't be a problem. However, no resistance is a sign that something is wrong with the cap and you might not have a secure connection. If you choose to put in a resistor you should know that it's not enough just to find a 1K resistor that fits. With the pulsating high voltages involved, many resistor types will be useless, some will break and on others the resistance will decrease with an increased voltage. You should ask for a suitable type. RakaD
1. Remove the Gas Tank.
2. The Coil will be exposed. Pull the red wire off the Spade Connector at the back of the Coil.
3. Remove the Two Bolts at the Coil and free the unit and wires from the Bike.
4. Peel back the Rubber Cap at the Coil. Both ends of my OEM coil wire were glued in with some sort of (dried) black adhesive sealer, similar to Yamabond/ThreeBond 1209, making an almost permanent connection. It was very difficult to get the wire to break loose. While dielectric grease is OK when replacing the Rubber, in the case of such a critical wire that might break loose when handling the spark plug caps, I prefer the permanency of the Yamabond/ThreeBond 1209 glue/sealant. It's also there to keep water out.
5. Now, grip the wire right next to the Coil, either by hand if you have a strong grip, or with a pair of pliers (NOT ViseGrips and don't hold too tightly), and unscrew the Coil from the wire. It easier to do this than undoing the wire from the Coil.
6. If you have new wires and Caps all moulded together, put the OLD rubber boot over the wire, with the wide end facing the end of the wire. Pull it up and peel it back so about 1-1 1/2 of Coil Wire are exposed.
7. Inserting the point of the Coil Screw in the centre of the new Coil Wire, and holding the Coil Wire firmly (it should NOT be allowed to twist excessively) screw the Coil onto the on the new Wire until you feel the Wire butt up to the end of the Blind Hole in the Cap. (The Wire will start to turn with the Coil, at which point you should stop immediately - Do NOT try to overtighten.)
8. Finally pull the rubber boot down the wire toward the Cap, until you can pull the boot over the new Cap. Repeat for the other Cap. That's it. You MIGHT like to test it before you start. See above for the testing procedure.
Technical Details about the Plug Caps:
While NGK Inductive Resistor Spark Plugs cost more than standard resistor plugs, they provide major benefits in late-model marine outboard applications.
Note that SOME MODIFIERS of the Plug Caps have had success with 5kohm caps. Maybe if the leads are REALLY fragged, 5k caps will be an improvement. But since 1k is more desirable, the 5k might not function as well as that alternative. Note that 1 kohm is advisable as it is closer to the OEM resistance e.g. Trawl one out of a BMW 2002 or find an NGK source (See above). Some modifiers have had worse performance with 1 Good BERU Cap than 2# 5kohm NGKs.
I actually replaced leads/caps simultaneously with NGK 5 kohm Caps and it worked fine. No noticeable mileage change Kristian #562
Corrosion: About the corrosion - when I looked into the cap (using a flashlight) I could see some greenish color. Opening the caps made me see a lot of corrosion, but Cleaning the parts didn't help. I would strongly suggest to people (specially you who are driving in humid conditions) to take the cap apart once in a while (10,000KM service perhaps) and clean it (it's a 5 minutes job). Spakur #1117
So, I rebuilt my wasted Beru cap by cannibalizing a resistor from a BMW 2002 plug cap (Beru 1Kohm as well, smashed the ceramic insulator with a hammer). This resistor along with the spring from an NGK plug cap did the trick. The resistor was a little shorter. When I first tried the NGK caps at right around 4100 RPM in fourth the bike would run very roughly. So bad that I almost thought something mechanical was wrong. I put the one good Beru cap back on and it ran much better and now that I have finally rebuilt the last cap it runs even smoother. Somehow water got in the cap, probably because I accidentally washed the bike, and corroded the heck out of the parts in it. Some electrolysis's?) occurred. I have no idea why some bikes might be different in regards to the 5Kohm plug caps, but my bike ran better with only one working 1Kohm versus the two working 5Kohm caps. Go figure. Chris in Santa Cruz, CA #782
I don't know about Chris's, but it certainly fixed mine. A week plus now and my bike is like silk and getting 15% better fuel economy as well. I have about 1000 more rpm usable at the bottom of the rev range and it's smooth all the way through. (i.e. gears 1-3 it'll pull away smoothly without stuttering from 2k5, with some roughness (but no stalling) from about 2k, gears 4 & 5 it's 3k/2k5.). Feels like riding a multi, the only vibration now is a slight buzz through the pegs. Amazing difference to rideability and the concentration level needed to ride the bike. (Reducing the number of gear changes needed on the daily commute makes a big difference) I did my rebuild differently from Chris, shorted out the cap with brass rod and used inductive leads, but the end result is probably similar. Increasing the plug resistance generally just increases the voltage rise time across the plug (and drops the voltage a little). That makes for a slightly weaker spark, and less RFI. Coil damage is pretty unlikely. (The plugs themselves change resistance from M ohms to milli Ohms in normal operation). I suspect the leads will unscrew from the coils. (Same system as the plug leads). If you can get them, inductive rather than resistive leads SHOULD perform a little better. Replacing those plug caps after THREE !!! unsuccessful trips to bike shops was the cheapest tune-up I've ever done. Pete
I am running NGK caps and they work fine for me. I did seal the wire around the boot though. Steve#417(IN,USA)
I have recently switched to the NGK 5ohm caps and think the bike is running rougher than before, mileage has definitely dropped. Gregor (Raceroo)
Checked plug cap terminals to ground with ohm meter; one was 3k ohms, other was 10k ohms, spec 6-13k ohms. Replaced plug caps with NGK XD05F from Dennis Kirk catalogue @ $3.20 each ($26 from BMW). Now one reads 13.89k and other reads 14.44k ohms, spec 6-13k. Readings on old caps after removing were 1.164K ohms for one, and the one that read low when on the bike now read 1.1M ohms (that's an M as in milli), then finally zero. Old caps stated they were rated 1K ohm. By the way, the stock plug wire is stranded copper. Seems the diagnosis was right and now all is well. Piece of cake job, cheap parts, bike runs noticeably better. And I no longer worry about my plug caps contributing to the death of the $300 regulator. Gary in Ohio.
If you find a 1 kohm resistor that works in the Beru plug cap on the F650, let us all know. It'd sure be cheaper to replace that resistor than the entire cap (I used a 5kohm resistor from an NGK cap when one of mine stock resistors went bad -- seems to work fine). Bob#550 (Olympia WA) (1 kohm ones are now available. See above ed)
In discussions with Mark403, I thought some mid range lag might have been due to my snorkle circumcision. More likely it is due to the above, and the fact that one of my OEM Beru (1k ohm) plug caps has tested at 50k ohms. Taking it apart, contrary to previous discussions, I'd like to report that the coil wire actually IS replaceable. It's metallic wire (non-resistive), not carbon, and can be carefully removed and replaced. The coil can be tested as an individual item, without the wire. So if you think you have a bad ($110) coil this is a $2 repair option that is worth exploring! Along those lines, our $38 plug cap can be taken apart (unscrewed from inside) without removing it from the bike. The probable failure is an easily removable ceramic cartridge resistor, similar to an automobile fuse. If we could find a source(?) of these resistors, cap repair could be a 5 minute, $2 job, keeping the OEM cap, as opposed to using a $5 NGK cap (which will probably last forever). As weird as it sounds, I like the idea of re-buildable caps. Might anybody have a source for Beru parts? Todd #389.
I measured my secondary coil resistance (the resistance between the plug cap and the coil core). The inner cap measured 32 MegaOhms, the outer cap measured 12.3 Kohms. Then I measured the secondary coil resistance AT the coil itself (measuring resistance between the HT output of the coil (where the big wire goes) and the core), it was 9.6 Kohms, right smack dab in the middle of the range (6-13Kohms). So I rebuilt my Beru caps by taking out the rusty resistor and spacer and just putting a solid piece of round steel stock in there. I did it, no discernable difference in engine characteristics but at least I can sleep better at night knowing my secondary coil resistance is within it's acceptable range. Shank NYC.
If your about to change the plug caps....use OEM. I changed to NGK and then 2 months (or so) later I changed to OEM. The performance was significantly better with OEM. The price was US$20 for OEM instead of US$8 per cap. Spakur in Sweden #1117, '95F
Why Beru Caps 1kOhm caps are better than NGK 5kohms ones. About the 25% loss. Ohms law U=R*I The resistance is (measured on my bike '95F): The Coil ~9K, The Lead 0K, The Cap 1K or 5K, Total resistance with Beru 10K, Total resistance with NGK 14K. The Voltage (U) is constant meaning that if the Resistance (R) is lowered than the current (I) has to compensate for that. So if you raise your Resistance (R) with 4/10 = 40% then the current (I) will drop with 28.5%. Spakur in Sweden #1117, '95F
My '99 does not have carbon core leads, it has metallic leads. I'd certainly prefer to replace the 1k resistor with another 1k resistor, if I could find one, but I was unable to. If you can find a replacement, as Chris has, good for you! Inductive / resistance HT wiring is a fine substitute, but it can be a little more delicate, sometimes more sensitive to aging than plain metallic wiring. (But it certainly can't be any worse than the crappy Beru resistors!) Obviously any new wiring and caps that are in the 1k range are better than old failing wiring or caps in the 50k range! Maybe we'll get enough feedback from Inmates to get some good data, just don't anyone compare old failing leads/caps with new replacements. Todd #389.
When I measured my plug caps, the resistance was WAY over the the range (32 MegaOhms for one cap). When I measured with a piece of metal stock in there, the resistance between plug cap and coil ground was 9.3Kohms, right smack dab in the middle of the range. So that's what's in my plug caps, and with it the test (plug cap to ground should be between 6K and 13K ohms) as it's mentioned in the manual checks out. Haven't had any problems yet. Shank NYC USA.
Non starter Ed UK My bike started to lose power under 4000rpm, then stalled. It would start up a couple of times after but finally died. Won't start at all now, just turns over, backfires and nothing. I put new plugs in. One of the idle mix screws was impossible to adjust and couldn't be drilled, so I replaced the carbs, properly set up. But still nothing. There is a spark and fuel but no starting. With the back firing I thought it might be the timing so I've just tried with a different black box, but no luck. Any ideas would be much appreciated. Well it seems to have been the plug caps. I changed them over and started the bike up. The HT leads did seem to be a bit loose so this could have contributed to the problem, but the new caps are on and they are staying. Ed UKEd Oxley #1262, Hebden Bridge, UK, '95 F650, R1100R, Moto Guzzi V50 III.
Faltering power. The last month I've been riding two up everyday since my wife started study v. close by me. Two up, plus laptops, and a heap of books - poor wee thumper! In that time the bike has steadily been loosing power? Hard to say how much - but it just does not seem to have "get up and go" any more. Also a puzzling thing is that at idle or low revs (under 3000) the engine seems to falter every few seconds - like it would with a fuel block, but only for a second, and on a regular interval. The bike is a 96 classic, 13k on the clock, and good condition. New plugs certainly helped, especially at idle - but didn't totally resolve things. I then tried replacing the leads and caps - worked a treat! Faltering power now completely smooth, bike back to normal. Cheers, Wazza
This FAQ was compiled & edited by Kristian #562, non-electrical person extraordinaire. Special Thanks to the Nameless one and to Todd for his patience.Thanks to Shank for the extras)