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Thread: Condenser failing?

  1. #1
    Atomic City Boxer 154048's Avatar
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    Condenser failing?

    My 1980 R100 has been misbehavin' recently...Running along just fine, then the GEN light flashes brightly on and the engine begins to sputter...similar to running out of fuel. When the GEN light goes out, the engine smooths right up.

    What is weird is that it can run for several hours with no issues, then I get a series of these electrical 'surges'...then it goes away and the engine runs beautifully. I have the stock ignition setup.(points in the can). This doesn't seem to be a charging issue...more that something is stealing the fire from my plugs..

    ? When a condenser is failing, might it show these symptoms? Or does it just quit entirely?

    ? If I might have a wire shorting out on an unfused circuit, could it draw enough power to pull the ignition spark down? (I have checked all the wiring under the front cover and under the tank and find no damaged wire. I have a Thunderchild diode board and all wiring is fine there?

    Thanks in advance.

    Steve
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  2. #2
    Administrator 20774's Avatar
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    Check battery grounds and cables.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Atomic City Boxer 154048's Avatar
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    Howdy Kurt,
    All is well with battery connections....I wonder if points themselves ever short out? Whatever it is really takes the life from the engine.
    I had to pull off the road this afternoon because the engine just wasn't running, then just before I rolled to a stop, it fired back up and off we went.
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

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    Condenser failure conjectures

    This may or may not be helpful.

    On my older /2, the condenser went bad, and the way it showed up was after an hour or so of riding, it apparently would get too hot. The engine just quit. I remember walking (pushing) my bike home (I wouldn't have dared leaving it where it stopped and picking up later and this was before cell phones) about 3 miles of uphill, and coasted downhill.

    I purchased a new condenser, cleaned the points, and it never quit again.

    There are others who may know more perfectly than I, but a condenser is a mini-capacitor. It stores up "small" electricity over a period of time and when circuit is broken (points break) it surges all that stored electricity in one large flash to the coils which in turn, produce the spark.

    I am wondering if there isn't some sort of ignition short or arcing (either in or around the coils causing the charging system to "see" a surge in electrical usage (causing the charging light to flicker or come on) and the short causes intermittent spark misfiring. I also saw something similar in my son't Volkswagon Golf. It had a slit in one of the spark plug wires. It would idle and run fine until under load (heavier acceleration) which would then cause the electricity to "find" an easier path of resistance. I can imagine if this were bad enough on a 4-cyl. engine (1 in 4 ratio) it would show up much worse on a 2 cyl. engine where 1/2 the power would be interupted.

    I recently purchased a 78 R100/7, and it has DYNA 3 spark system on it. Seems to work perfectly, though I almost always distrust electronic anything on a transportation vehicle.

  5. #5
    Macrunch MCrenshaw's Avatar
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    Suggest that you inspect the coil. They will go bad after this time. Inspect carefully for hairline cracks.

  6. #6
    Atomic City Boxer 154048's Avatar
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    I have a spare condenser and will put it on. In my case also, the problem happens after I have been riding quite a while...today it shorted after 2 1/2 hours riding...and when it began to act up, I barely got it home.

    Next, I will check the coil for cracks...are these visible to the unaided eye?
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

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    I have had two similar issues with my /5 both on longer road trips. While heading to Laguna last summer for the GP races, (awesome trip but that's another story), my rock-solid never-miss-a-beat airhead started missing, it would run fine for an hour then without warning sputter a few times, run fine, then another series of misfires, very disconcerting when you're 500 miles from home. That evening at a hotel parking lot I checked everything in the ignition system over carefully and systematically. Points were a little worn but gap was OK, wires and all connections were tight and clean, nothing seemed wrong. Out of desperation I put in a new condenser and it hasn't skipped a beat in the last 8000 miles since (how's that for a jinx!?). I can't say conclusively that the condenser was at fault, of course it's possible that during my inspection I inadvertently wiggled some other connection and fixed the problem but what the heck, I'm going with the condenser.

    More recently my bike developed a symptom even more similar to your description, on the road for an hour or so the bike lost power and I noticed the gen light on for a second or two, then it quickly returned to normal running, a mile later same thing but the light stayed on, I touched the ignition switch (pushed the key down) and all was well, I ended up riding the last few miles home with one hand holding the key down just to keep it running. I found that the key contacts were pitted and making a poor connection, I used a points file to clean them up and replaced the key since the little detent grooves were worn and I'm not sure if they were holding it in well enough. (I know your later bike has a different switch set-up than my artifact but I'm suggesting that the switch might still be a thing to check out, wiggle the key or whatever and see if it effects the issue).

    I've found with a lot of electrical problems, whether in switches or contact points, as the surfaces corrode or wear the resistance increases, this leads to further burning and heat, these things seem to take a few miles or a few hours to develop and can be very frustrating to diagnose. Good luck with yours!

  8. #8
    ABC,AMA(LIFE),MOA,RA,IBMW MANICMECHANIC's Avatar
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    I was at a tech day recently and observed something similar. The Airhead who investigated and found the problem was baffled for a long while, but discovered that the pivot pin on the advance mechanism on one side would occasionally contact the wire connector on the points. Bending the connector over just a bit solved the problem. Problem went away. Just something else to consider.
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  9. #9
    Atomic City Boxer 154048's Avatar
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    Thanks for the tips, Gents. I will report back as to what I find..
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  10. #10
    MOA #24991 Pauls1150's Avatar
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    +1 Yes to ALL of the above, plus: Look closely at both surfaces of the points. If one side has a buildup (possibly somewhat conical) and the other side is pitted, that's often a sign of condenser failure.

  11. #11
    Unfunded content provider tommcgee's Avatar
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    Look for cracks in the coil in the dark. They light up.

    I will refrain from using the word short, it does have an exact electrical meaning, but you seldom see anyone get it right.
    Salty Fog Rally 2007, 2009, 2011, 2012, AND LOOKING FORWARD TO 2014!

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  12. #12
    Curmudgeon nrpetersen's Avatar
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    All good ideas - except why does the GEN light come on? Suppose it could be an intermittent short-to-ground of the lead into the points can?

    Good luck finding it!
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

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    Key switch

    Wow - a great plethora of ideas and every one of them seems plausible.

    I really appreciate the one about the key switch. That one sounds very likely as it would account easily for both the missing AND the gen light issue.

    This is why I love these forums. Even though I don't have this problem now, I hope I remember all of these when I DO have the problem!

  14. #14
    Atomic City Boxer 154048's Avatar
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    Greetings Gents,

    Well I replaced the condenser and took several multi hour rides. No reoccurance of the initial problem (engine missing), but when I rode it this morning, occasionally the GEN light would come on (say, at a traffic light)...at the same time the Tach would bounce up a thousand RPM or so...with no increase in actual engine speed. These intermittant electrical quirks are quite the number...

    I will continue my search for corroded or loose connections...
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

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