sudden loss of power

[gltriker]

Post#76

I changed the wiring of the Dyna S to get power at the black+black/brown wires just outside the coils (with an inline fuse). Still drops all power after warm up. I looked into testing the Dyna S module

https://www.mpsracing.com/instructions/ ... esting.pdf

and it says to disconnect the wires from the coils then OHM test between the backing plate and the wires. It should read open and any other reading means a damaged unit. So when I did this my reading never changed and stayed at (1) on the multimeter. So time for a new ignition module?
(I'm just double checking that I read and followed directions correctly because who knows where my brain is these days)

Immediately after the engine cold starts and continues to run, correctly, Individually probe both Dyna S leads connectors up underneath the rubber umbrella with your static timing test light. That tests the dynamic operation of the primary ignition circuit for each ignition coil. The low voltage test light bulb will flash at both test points in synchronization with their respective ignition coil discharge events.
When the still running engine exhibits a 'sudden loss of power', individually probe both plugged-in connectors under the rubber umbrella, again.
If one isn't flashing when the engine starts running poorly, you have discovered a fault in the primary ignition circuit for one of the two ignition coils does exist.
Quite likely the Dyna S module in that ignition coil's primary circuit is problematic.

Screenshot_20240618_122339_Gallery.jpg

video download

20221025_152106_1_1.mp4

*******
NOTE: After cranking the engine to demonstrate how the primary ignition system responds to my dynamic testing procedure, you will observe me momentarily bump the starter 4 consecutive times. First 3 momentary bumps end with the test light bulb turned off. The last momentary bump ends with the tester light bulb steadily illuminated. Why? The Dyna S rotor magnet is aligned with its primary ignition circuit ground path switching module. Same effect as having a breaker points' contacts open when the crankshaft stops turning. Make and break... solid state

Screenshot 2025-06-16 020237.png

Report back with testing results, please.

[sickradsean]

Thank you. I think I had just missed your previous advice amidst all of the other info offered. I HAD skipped the voltage test because it was testing the coils and wires which I had just replaced, but I can see the error in that now. I made myself a static test light (per octanes example in the how to) and checked/adjusted the timing. I’ll fire up the bike tomorrow and see how the light flashes while running and if one side cuts out when the bike starts to die.

[redglbx]

A couple of things to add, I was having a problem with my 76 where it was popping out the tail pipes at low rpm/idle once it was hot. The last time I rode it was about 2 years ago due to severe back problems and major reconstructive surgery so it’s been bugging me for a while. Anyway when I last rode it I noticed that the voltmeter was giving me some strange readings where it would intermittently show low voltages as low as 6v but bounce back to the normal 13.2-13.4v, the bike ran a little weird but seemed ok.

Anyway I got to look at things yesterday and found a dead battery. I keep things constantly on a battery tender and measuring the voltage showed 6-6.5v. I put a normal charger on it and it quickly came up to 11.5v but as soon as I pulled the charger off and tried cranking it,it would drop back to 6.5v and stay there, bad battery (7+yrs old) probably a cracked plate, no complaints. Another “good” battery in and the bike runs much better, still pops but much less.

So the next thing up I started checking the NGK plug caps which should be less than 5k ohms, which they checked good but the pin/screw that goes into the wire on one was green so I cleaned it with some electronic cleaner and I clipped about 1/4” off the wires before screwing them back in. I think I’ll replace the green cap even though it measures fine. Surprisingly no more pop ! Bike idles perfectly ! I am happy !

While I was putzing around I thought I would look at the Dyna power lead since we’ve had a lot of talk about clipping it into the black coil power feed, surprisingly I found that at some point I had already moved it to the black wire at some point. Getting old is a bitch, with the CRS thing !

I did measure the voltage at that connection and found it ran from 11.7 to 12.9v running or just sitting with the key on, the 12.8 was with it running. I was thinking of adding a relay to give the feed full battery voltage because of something S-Car Bob said that made me think that having the Dyna tied into the coil feed would not allow the ”kill” switch to kill the motor but it works fine, no relay needed.

One other thing to check is that with the Dyna installed you need to have the gasket on the points cover cap and a grommet around the wire from the Dyna coming out of the points housing. The wires can & do chafe & short against the housing, it will cause all kinds of intermittent problems including shorting the module out. One thing to remember is that the cover gasket is no longer available or the grommet, I made a new gasket from a piece of rubber that is a bit thicker to better space the cover out from the Dyna, the grommet can be made from a grommet from the auto parts store. Some liquid tape helps with all this as well.

I realize that all this is a bit long winded and am hoping it will help with some of the intermittent issues we seem to see with these bikes. So for advice I would suggest 2 things, load test your battery to insure it is good & check your plug caps so that they are less than 5k ohms and if they are clip a little off the wires to get a new & clean connection, it makes a difference even though it’s a small thing! Hope all this helps !

[Sidecar Bob]

Um.... 11.5V is close enough to fully discharged that it doesn't matter (see chart below) A fully charged battery should measure 12.7V.

FWIW, the voltmeter on Mr.H is connected right at the keyswitch and it normally reads 14.5 at RPM above idle and IIRC, about 14V or perhaps a bit less at idle. I would expect to read pretty close to that on any black wire on the bike (all there is between battery + and the black is the main fuse and the keyswitch) so if I measured less than 14V on any black wire with the engine running I'd be looking for a reason (I think I'd check the voltage across the battery and if it was low too I'd b testing the stator)

Flooded battery voltage vs charge.gif

[gltriker]

Thank you. I think I had just missed your previous advice amidst all of the other info offered. I HAD skipped the voltage test because it was testing the coils and wires which I had just replaced, but I can see the error in that now. I made myself a static test light (per octanes example in the how to) and checked/adjusted the timing. I’ll fire up the bike tomorrow and see how the light flashes while running and if one side cuts out when the bike starts to die.

[gltriker]

Post#81

Thank you. I think I had just missed your previous advice amidst all of the other info offered. I HAD skipped the voltage test because it was testing the coils and wires which I had just replaced, but I can see the error in that now. I made myself a static test light (per octanes example in the how to) and checked/adjusted the timing. I’ll fire up the bike tomorrow and see how the light flashes while running and if one side cuts out when the bike starts to die.

Sean,
I can't fault you for not fully performing the Voltage Test. Why not?
Because there are no words in that static testing procedure-with a voltmeter- to direct the Dyna S system's tester to Carefully perform the complete Voltage Test, again, when the engine and Dyna S are mechanically HOT; at Full operating temperature, when the Dyna S system seems to be most problematic.

[sickradsean]

Immediately after the engine cold starts and continues to run, correctly, Individually probe both Dyna S leads connectors up underneath the rubber umbrella with your static timing test light. That tests the dynamic operation of the primary ignition circuit for each ignition coil. The low voltage test light bulb will flash at both test points in synchronization with their respective ignition coil discharge events.

This process makes sense but when I touch the hot end of the test light to either individual coil wire connector It grounds out the coil and the bike instantly dies. I set up the light the same as when static setting the timing. Black wire to frame ground and red to whichever coil is being tested.

I'm doing it wrong?

[gltriker]

Immediately after the engine cold starts and continues to run, correctly, Individually probe both Dyna S leads connectors up underneath the rubber umbrella with your static timing test light. That tests the dynamic operation of the primary ignition circuit for each ignition coil. The low voltage test light bulb will flash at both test points in synchronization with their respective ignition coil discharge events.

This process makes sense but when I touch the hot end of the test light to either individual coil wire connector It grounds out the coil and the bike instantly dies. I set up the light the same as when static setting the timing. Black wire to frame ground and red to whichever coil is being tested.

I'm doing it wrong?

hmmmm?
I utilize a typical generic off the rack low volts probe type voltage tester. Nothing special about it.
-At the far end of its extended wire lead, the alligator clip is clamped onto the negative battery terminal.
-The sharp end probe is then inserted into the open side of the primary terminal to be tested, under the rubber umbrella.

The wattage of the bulb utilized in your Octane configuration tester may be excessive to perform dynamic primary ignition circuits' testing?

[Sidecar Bob]

What size of bulb are you using? You would need one that doesn't draw much current...

[sickradsean]

Here is what I was working with. You can see the red(+) end plugged into where the dyna connects to the harness and the black(-) end clipped to the ground wire (bulb at the top of frame). It is a standard 12v turn signal bulb.

At first I thought that I had the polarity of the bulb backwards and that was the problem, nope. Then I looked to see if I had a smaller bulb, nope. So I tried running the check again (cold engine), and again when connecting the positive side to either of the coil wires the bike would lose power (obv because the bulb is pulling voltage).

But then I thought about using this method in a reverse fashion! What if instead of looking for the bulb to glow I look for it to be a kill switch that would not show up on the bad pickup wire? I warmed up the engine (which incidentally sounds so smooth when running right) and then as soon as the idle dropped off I tested both wires. Sure enough connecting to black wire will consistently kill the engine, while connecting to the white wire does nothing! So then this tells me the pickup connected to the white wire dies when its heated and the bike is only running on two cylinders. Yes?

[gltriker]

Yes.

the Dyna S system part number is: DS1-3

[Sidecar Bob]

The filaments of incandescent bulbs don't care about polarity (they can even run on AC). The only concern about polarity is that the shell of the base is usually connected to ground but the same bulb we use in our negative ground vehicles would work fine in positive ground systems.

Bulbs (or any other electrical loads for that matter) don't "pull voltage", they draw current. Voltage is pressure and current is flow and yes, if you draw too much current it can pull the voltage down to a lower value but it is the current that does that, not the actual load. This may sound like I'm playing word games but if you learn to think in the correct technical terms it will help you to understand what is actually happening.

But that isn't the problem in your specific case. The bulb you are using is an 1156 type (or equivalent), which has a resistance of something like 6 or 8 ohms. Mike's article about coils that I linked to in an earlier post explains why some coils have different primary winding resistances and why that doesn't really matter most of the time but the specific case of connecting a bulb in parallel with the coil's primary winding is one of those rare instances where it does. If the primary winding is 3 ohms and you connect that 6 ohm bulb across it about 1/3 of the available current will flow through the bulb and there won't be enough current through the primary to create good sparks.

If you used a 3W bulb like the ones used to light the instruments its resistance would be 60 ohms or more and the current flowing through it would be something like 5% of what flows through the primary, still enough to have a measurable effect but not enough that you would be likely to notice.

Dynatec is very specific about how long they warranty their products (I believe it is 1 year on the Dyna S) but they have been known to extend that in specific cases.
When mine failed it was out of warranty a few weeks. At the time people on the forum said that Dynatc usually offered out of warranty replacements at half price so I contacted them. They had me ship them the defective one for testing and extended the warranty because it was so close and I had explained that I hadn't installed it for a couple of months after I bought it.
That was 2013 and it was still working when I drove the bike to the storage shed last fall.

[sickradsean]

Yup, it was a bad ignition pickup that shorted out when it heated up! I've installed a new ignition and everything is running smooth for the last 40mi. I'm going to check the valves and read up on advancing the timing to get everything running smoother, but she's moving down the road alright now. Thanks for all the help tracking down this problem. At least now I have a whole bunch of stuff thats replaced and won't be a problem in the future (coils, ignition, wires, fuel lines, petcock, general wiring clean up)

[gltriker]

Very good news
Not sure about advancing the ignition timing, though. No good reason to do that

Done