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Thread: r50 no spark

  1. #1
    vlambert
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    r50 no spark

    So today I removed my advance unit for inspection. I cleaned it and replaced it, and now I have no spark. The advance unit is properly seated, the magneto is properly timed, and the static timing is spot on. No spark at all. The bike has a Benchmarkworks 12 volt alternator conversion (which shouldn't matter I think), and a conversion points plate. I replaced the points and condenser...nada. Any recommendations as to what (and how) to troubleshoot next? I'm totally perplexed...

  2. #2
    Liaison 20774's Avatar
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    Recheck the wire for the condensor. I'm thinking that you have it connected wrong and that it is not isolated correctly. When that happens, the points open-closing won't create a spark like it should.

    Also, the wire that goes to the magneto is critical as well. Both of these wires must be properly connected. Actually, to set the timing with the magneto, you have to disconnect the magneto ground, otherwise the points don't work. So, likely there's something wrong there.
    Kurt -- Forum Liaison ---> 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
    The terminal where the coil and condenser attach to the points has a small, insulating washer with a shoulder that keeps the coil, condenser, and points arm from contacting ground. You are either missing that part or, as commonly happens, the part has shifted allowing a path to ground.

    Turn the engine until the points are open then put the key in the ignition. Measure from the mounting screw where the coil and condensor meet the points to ground. It should read OPEN. Edit: that is incorrect. It should read about 1/2 ohm. That's the resistance of the primary winding of the coil. If it reads closed (0 ohms) take the connection apart and make sure that insulation washer is in place and that the parts are connected properly.

    It's in the parts book as 12 11 8 004 136 but the diagram doesn't help much with its proper placement. At least I think that's the proper part number for the needed insulator -- might be wrong.
    Last edited by marchyman; 03-06-2011 at 07:37 PM.

  4. #4
    vlambert
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    Here's what I checked: with both the magneto (coil?) wire and condenser wire attached to points, points open and ignition on, I get connection to ground. With both wires removed from points, no connection to ground. With condenser wire attached to points no connection to ground. Then I checked the magneto wire by itself, and found that it had a connection to ground with the ignition on. I'm thinking this isn't right from what you guys said. I also removed the magneto grounding wire from #2 on the ignition switch just to rule that out, and then from the magneto itself in case there was a short in the wire somewhere; still no spark, still reads connection to ground from the magneto.
    Last edited by vlambert; 03-06-2011 at 12:54 PM.

  5. #5
    Liaison 20774's Avatar
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    I always have trouble remembering this, but IIRC the action of pulling the key from the headlight actually grounds the magneto and kills the engine. So that means, for the bike to get spark, the magneto must be ungrounded. If your wiring always grounds the magneto, then it won't run.

    As has been said, you need the wires connected properly at the small screw on top of the points.

    Test this out. Hook things up the way you have been...the engine doesn't spark as you said. Put one lead of your ohm meter on the points right where these wires attach and the other lead on the engine case. Set the meter to ohms or for the buzz to show cotinuity. If the points are grounded, you should show 0 ohms or hear the buzz going off. Rotate the engine. Does the ohm meter ever show infinite ohms or stop buzzing? Probably not. Then unhook the wire to the magneto. Repeat rotating the engine. Most likley, at some point in the rotation, the ohm meter will show infinity or stop buzzing, meaning that the points have opened. When the points open, the ignition system is supposed to spark.

    That might tell you that you can get a spark if you can get the magneto wire attached properly.
    Last edited by 20774; 03-06-2011 at 12:58 PM.
    Kurt -- Forum Liaison ---> 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!

  6. #6
    vlambert
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    I've removed the two high tension wires from the magneto as well as the ground wire from ignition switch #2 (at the magneto); the wire that goes to the points from the magneto (unconnected) still reads connection to ground. Am I looking at a new coil, or ? Pull the magneto rotor first, and check it out?

  7. #7
    vlambert
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    I guess I'm getting ahead of you, but I did do as you said, and when the points are open and the magneto wire disconnected, there's no connection to ground through the points. HOWEVER, the wire from the magneto ALWAYS shows a connection to ground, even with everything disconnected from the magneto. I'm thinking the coil might be shorted? Any way to test this?

  8. #8
    Liaison 20774's Avatar
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    Quote Originally Posted by vlambert View Post
    I've removed the two high tension wires from the magneto as well as the ground wire from ignition switch #2 (at the magneto); the wire that goes to the points from the magneto (unconnected) still reads connection to ground.
    I don't understand what you're measuring. "The wire that goes to the points from the magneto...reads to ground". If you connected the ohm meter to the end of this magneto wire and then the other end to the engine case, seems to me that you would show continuity. That is, that wire IS connected to ground.

    As for testing a coil, you can check the secondary resistance across the two high tension lead connections on the coil. It should be around 17K ohms. You may have coil failure. Often times, a weak coil exhibits difficulty in starting when hot, as the interior wiring separates, reducing the amount of energy the coil can store. For starting, you need everything you can everything you can get out of the ignition speed to start the bike at kicking speed.

    There's a replacement coil available called the Emerald Isle coil. Solid state...fits very nicely.
    Kurt -- Forum Liaison ---> 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!

  9. #9
    vlambert
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    After rereading your post #5, I think I misunderstood. I thought you were saying that WITH the magneto wire connected to the points, you should be able to read infinity when the points are open. But if that wire always has a circuit to ground, I see that that's not the case. I've disassembled the whole works (except the magneto rotor) and have found that; my coil has a reading of about 17k ohms between the two high tension leads, so I guess it's not shorted. There is really only one place and way to attach the wire from the magneto to the points and the points to the condenser, this is a pentacomm points plate with GM points, and I definitely had it attached right. Hmmm, don't really know where to go from here.

  10. #10
    Liaison 20774's Avatar
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    So this is what you have?

    http://www.flickr.com/photos/roundel...in/set-355734/

    This isn't a great picture, but this is the connection on my R69S. You can see the black wire coming from under the coil and connects to the very top of the bolt along with the condensor wire. Note the tan colored isoloaters. These have to be there as well.



    Not sure what to say other than to relook at everything and hook things back up again. You said you removed/replaced the advance unit...shouldn't have affected things. But you also said you replaced the points and condensor. That must be where the issue is...they didn't get back together the right way.
    Kurt -- Forum Liaison ---> 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!

  11. #11
    Quote Originally Posted by vlambert View Post
    After rereading your post #5, I think I misunderstood. I thought you were saying that WITH the magneto wire connected to the points, you should be able to read infinity when the points are open.
    My error... I stated that and it is incorrect. I edited my original post to highlight my error. You will measure the very low resistance of the primary circuit. If you are using a continuity tester it will likely read as shorted. You'll need to get a good ohmmeter and put it on the lowest scale. The primary circuit resistance on a stock coil will be around 1/2 ohm.

  12. #12
    vlambert
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    Measuring the resitance across the primaries with a good digital multimeter, I get 0.0 ohms. So maybe the coil IS bad? Would this mean the windings have fused?

  13. #13
    Liaison 20774's Avatar
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    Well, Marc said that it was going to be low, and 0.0 is low!! It's in the right range for the reading, so no, I don't think you have a coil problem.

    Since the only thing (that I can tell) that you did that could affect this was change the configuration of the magneto and condensor wires. Pulling the advance unit off shouldn't have affected anything. Unless in putting it back, you accidentally stretched the points spring to the point that it's "sprung". Are you physically seeing the points open and close? If the points don't actually open, then you don't get the collapsing field in the coil to get the spark. If the points never close, then you don't get current to flow through the coil to saturate it.
    Kurt -- Forum Liaison ---> 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!

  14. #14
    Quote Originally Posted by vlambert View Post
    Measuring the resitance across the primaries with a good digital multimeter, I get 0.0 ohms. So maybe the coil IS bad? Would this mean the windings have fused?
    Measured when connected to the points or not? Measured with the key in or not? To take the key and the headlight bucket switch out of the picture I'd remove the brown wire going to the coil, then remove the coil from the points, and finally measure from the lead normally connected to the points to ground.

    I got .5~.6 ohms with a high impedance DMM. I got the same reading on my 25 year old analog Radio Shack meter once I remembered I had to zero the meter *after* switching resistance scales.

    Of course, that is a sample of one and perhaps the coil I'm checking against has an anomalous value.

    I'd suspect mis placement of the spring lead from the points as the source of your non start issue, but only because I've had that problem myself when switching points.

  15. #15
    vlambert
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    Quote Originally Posted by marchyman View Post
    Measured when connected to the points or not? Measured with the key in or not? To take the key and the headlight bucket switch out of the picture I'd remove the brown wire going to the coil, then remove the coil from the points, and finally measure from the lead normally connected to the points to ground.
    With everything disassembled (for the fourth time) and on the bench by itself, the coil measures less than 0.1 ohms across the primary leads. After reassembling everything again, I got the inspiration to turn the lights out while I kicked it over and saw that I did have spark, albeit very weak. So I pulled the magneto rotor and reset it using the Barrington guide's recommendation of having it timed at the points plate mark when the magneto body is centered (so the Abrisz point is correct?), reassembled everything, and it started first kick! The spark is still very weak though.

    A little background: the bike is new to me, so I don't know it that well yet. The magneto was timed properly, just not with the magneto body centered. The points are GM points, so I don't need to worry about the isolation washers (they're built in); there's really no way that I can see to mess the connections up (although this wouldn't be the first time!). I haven't run the bike long enough to see if it starts hard after it's warm yet even, but I'm a little worried about the weak spark.

    Thanks for all your help guys, I probably did have something wrong on retrospect, but what do you think about the weak spark?

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