I have 71 Triumph that had similar symptoms- 2 cylinders-2 coils- no spark one side- switch wires- no spark other side- new coil, spark 2 sides, you're on the right track
On 6/8/09, Dennis <[email protected]> wrote: > > > Jean-Pierre, > > Quite a lot has happened since I wrote the message you responded to. In > the > end, I simply swapped the two coils and the problem moved from the 1 & 4 > plgs to the 2 & 3 plugs. I believe that this proved that one of my two > coils was bad. I have another one on it way to me now so in a day or two, > I will know if this theory is correct. > > Thanks for your thoughts. > > Dennis G. > - Seattle > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: 08 June, 2009 01:56 > To: [email protected] > Subject: [Nighthawk Lovers] Re: My CB700SC and the CDI unit > > > > Hello > > At that point, I would make a harness to connect the pulse generator to the > cdi unit, allowing to measure the signals of the pulse generator on an > oscilloscope. Simple to do with faston clips. Making the same type of > harness on the output of the cdi to the coils would allow to monitor the > output signals. Seing both pulse generator signals on the scope would allow > to check for integrity (up to the harness). Monitoring on each pair of > cylinders the input/output of the cdi would allow to check for it's > integrity. And if you get two good signals to the coils and still no spark, > the problem comes from the coils / their ground connection / the wires / > the spark plugs. If you don't have an oscilloscope, ask somebody in > electronics business : lot of people have old ones at home. You can even > find now, on ebay or else, cheap multichannel scopes which are just > peripheral of computers. > > By the way, I would not rule out so fast the fact that different cdi units > could loose preferably one channel, always the same : could be normal with > lost of capacity of electrolytic capacitors, given such or such design. > Like getting too low water pressure feeding a a washing machine would > always make the same type of apparent defect. I discussed this week end > with a friend, amateur of cars of the end of the seventies / beginning of > the eighties. Had the same problems with one of his cars cdi... ended up in > changing the electrolytic capacitors. I was on the way to make this type of > diagnostic on my 650 CBX, when abruptly, this week end, it failed : no more > sparks at all. Had to go and take it with the car and trailer, fortunately > close from home. Will see later what happened. > > Regards > JPD > > > At 19:46 05/06/2009 -0700, you wrote: > > >Well, my new Ignitor unit came and I installed it and my bike still has > >the same symptoms. That is, cylinders 1 and 4 are not getting any spark. > > > >I sat down and had a longer look at the schematic and I can see some > >possible scenarios that might be consistant with the facts on hand. > > > >Those facts are: > > > >- I've measured the resistances of both my primary and secondary coils > >and > >my pulse generator coils and they all show continuity and resitances that > >are within spec. > > > >- I've tried two different Ignitor units (my original and the new one) > >and > >the system fails the same way with either (no spark on 1 & 4). > > > >Scenario # 1 is that the new ignitor unit is bad in the same way that the > >old one is, i.e. failing on the cylinder 1 & 4 side. I don't think much > >of this idea however - seems like too big a coincidence. > > > >Scenario #2: that even though the pulse generators both measure good > >on > >continuity and resistance, the one that sends the signal for 1 & 4 may, > >somehow, be out of place relative to the central shaft that spins with > >a magnet on it to generate the pulses. I'll be able to see this, I > >think, by cranking the bike and looking for voltage pulses coming up the > >cable from the pulse generators. If both sides have similar pulses, then > >I think this won't be the issue. If one pulse is low or mssing, then I'll > >open the pulse generator cover and see what's what in there. > > > >Scenario #3: one of the connectors linking the pulse generator cable to > >the Ignitor may be corroded and not passing signal. Frankly, this seems > >remote to me. The surfaces seem clean and I've plugged and unplugged > >them several times. > > > >Scenario #4: The wire that carries the 1 & 4 signal from the ignitor > >to > >the 1 & 4 coil may be open. I can run a simple continuity test to demo > >this. I know the ground wire and the 2 &3 wire from the ignitor to the > >coils has to be good as I've got spark on 2 & 3. > > > >Scenario #5: The wire on the coils that carries the ground from the 2 & > >3 > >side to the 1 & 4 side may be open. > > > >Scenario #6: The connection where the 1 & 4 signal from the ignitor > >connects to the 1 & 4 coil may be corroded and not passing the > >signal. I've had this disconnected and reconnected and it seems unlikely > >to me like in #3. > > > >Dennis H., are you reading this? I'm looking at page 19-0 in my CB700SC > >manual and I'm wondering if I'm missing some other scenarios? > > > >Dennis > >- samadhi<soft|coda|muse>.com > > > > > > > > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en -~----------~----~----~----~------~----~------~--~---
