Dyna S causes 3V drop at coils?

[Coady]

Recently replaced my points ignition with a dyna S. My bike has appeared to be running rich since - bit of black smoke and dark plugs and also down on power. Initially I thought this was carbs/jetting as I added 850 pistons around the same time as the dyna S. Then I noticed a slight miss at higher revs and thought stuff it I'll get green 3 ohm dyna coils too and 8mm suppression leads.

So I've replaced the coils and still running average.

Now just before I replaced the points, voltage at the coils was around 12.25 with engine off and I hadn't checked it again since before adding dyna S as I assumed it would have been the same.

So I add my pretty new green coils and check voltage & it's dropped to 9.5 V??? So I figure rapid corrosion somewhere along the line... So I start checking connections with my voltmeter and find no significant drop and then I disconnect the red power wire from the dyna S (even though its after the coils) and measure 12.25V from the wire that splices into the orange/white wire that powers the coils. So I check the coils and sure enough they're 12.25V as well. Plug back in the dyna S and voltage back to 9.5V.

So the dyna S is causing an almost 3 volt drop. This can't be normal. Any ideas?

Thanks

[SqDancerLynn1]

What is the battery voltage when this happens ?? Could be bad battery. Have you checked the voltage on both sides of the ign Switch. Check the difference between the battery voltage and the voltage on the orange fuse block wire.. What happens to battery voltage when you turn the lights on ?

[Steve]

Going along with what Lynn says.

Another way to check: connect your bike to another battery (lawn tractor, car, truck, whatever), but be sure the donor is NOT running.

Do your same voltage checks and report the results.

My guess is that your battery is starting to go. Actually, it appears to be well on its way.

By the way, do you have resistor caps on your suppressor wires? That could be too much resistance and contribute to your miss at high revs.

.

[Coady]

Thanks for the reply but battery is good 3 mth old motobatt and charging system good. Turns over and starts straight up. lights on, engine off, slowly bring battery down to 12 volts then lights off and it rises back up to over 12.5.

And when the engines running the coil voltage is still only 9.7 V with the dyna S attached (obviously). With the old points coil voltage was always over 12.2 V running.

Surely the dyna S should barely draw any power normally?

And no I don't have resistor caps on suppressor wires. Thanks

[salty_monk]

I had this on an 80 1000G. I was using the 12v switched from the old ignitor plug to power it.... when I put the switched live elsewhere the problem went away.

Why don't you put in a relay to switch both the coils & the Dyna S direct from the battery, that would cure it....

[Steve]

Thanks for the reply but battery is good 3 mth old motobatt and charging system good. Turns over and starts straight up. lights on, engine off, slowly bring battery down to 12 volts then lights off and it rises back up to over 12.5.

It might do all that, but please try a check using a high load:
- Connect your voltmeter to the battery, record the voltage.
- Turn the key ON, record the voltage, note if it is dropping, and how quickly.
- Start the bike, note the voltage while it is cranking (and record it).

I have had three cases of bad batteries in the past year. The first one, I got a new AGM battery for one of my 850s. My son took the bike to Flori-duh for the winter, the battery failed in about a month. He got a replacement AGM battery of the same manufacturer, because that's what I had put in it. It also failed in about a month, but this time, I was down there to help him. We learned that both of them were part of a bad batch of batteries that had been distributed by Batteries Plus, and got free replacements. We (I) paid a little extra to get their premium battery instead, and have had no further problems.

The third battery was in my van, which I had recently acquired. Never had any problems starting it, running it or anything else, but noticed that the interior lights were not very bright when the engine was not running. Voltage at the battery was only 10.1 when the engine was off, but 14+ when it was running. I measured voltage from cell to cell and found that there was one dead cell. In spite of having a totally dead cell, it still seemed to work quite well.

Motorcycle batteries don't have the reserve that a car battery does, so please do a quick check of your battery under load.

.

[Coady]

Motorcycle batteries don't have the reserve that a car battery does, so please do a quick check of your battery under load.

.

Fair enough. I'll test the battery more thoroughly when I can get to the bike later today and see what I come up with. I'll give it a good charge too. Thanks for the suggestion.

It just seems odd that the voltage drops instantly to 9.5 with the dyna S connected - do they normally draw a lot of power? I wonder what else could cause this?

[SqDancerLynn1]

YOU HAVE a charging problem !! When you are checking it while running ? you should have around 14-14.5 volts

[Coady]

YOU HAVE a charging problem !! When you are checking it while running ? you should have around 14-14.5 volts

OK. I was previously referring to the voltage at the coils when running, not at the battery and the point I was making was that they were always over 12 volts with the points system not around 9.5 . From memory there was a 0.5 Volt drop between battery & coil. And the voltage was atleast 13.5 volts at the battery when running. However I haven't checked the charging system for a couple of months and I'm certainly no expert on this stuff. And since you guys are all hammering on about it I'll go over battery and charging system first and see what pops up.

Appreciate the help.

[posplayr]

OK. I was previously referring to the voltage at the coils when running, not at the battery and the point I was making was that they were always over 12 volts with the points system not around 9.5 . From memory there was a 0.5 Volt drop between battery & coil. And the voltage was atleast 13.5 volts at the battery when running. However I haven't checked the charging system for a couple of months and I'm certainly no expert on this stuff. And since you guys are all hammering on about it I'll go over battery and charging system first and see what pops up.

Appreciate the help.

This is a quick test to see if the charging system is working.

Want to just get a feel for how the charging is working? Do a Quick_Test

[Coady]

This is a quick test to see if the charging system is working.

Want to just get a feel for how the charging is working? Do a Quick_Test

Thanks for the link, I've posted it below with my results in bold:


Quick Test Steps:

1.) key off................Normal 12.7 volts-12.9 volts : MY RESTING VOLTAGE 12.5 (BATTERY HASN'T BEEN ON CHARGER AT ALL)

2.) key on (but not cranking with lights for 10 sec).....Normal 12.2-12.5 volts : WENT DOWN AND STOPPED AT 11.95 AFTER 30 SECONDS OR SO WITH LIGHTS ON AND KILL SWITCH ON.

3.) at idle (1500 rpm).....12.6volts - 13.2volts : 12.8 VOLTS

4.) at 2500 rpm 13.5 -14.0 volts : HOVERED AT AROUND 13.4 VOLTS

5.) at 5000 rpm.....14.0 -15.0 volts : VOLTAGE STARTED DROPPING OVER 3000 RPM, NEVER GOT HIGHER THAN 13.4.

6.) key off.....slightly higher than measurements # 1 (12.8-13.0 v) : YES SLIGHTLY HIGHER, NOW ON CHARGER.


So from your diagnosis summary it looks like my main problem is bad connections from test #5. I reckon the battery is probably fine and is just undercharged because of this. But I'll do this quick test a gain with a full charge to be sure.

Thanks again for the link Posplayr. I'm gonna hit the stator pages again too now and get this charging system better.

Which brings me back to the dyna S...???

[posplayr]

Thanks for the link, I've posted it below with my results in bold:


Quick Test Steps:

1.) key off................Normal 12.7 volts-12.9 volts : MY RESTING VOLTAGE 12.5 (BATTERY HASN'T BEEN ON CHARGER AT ALL)

2.) key on (but not cranking with lights for 10 sec).....Normal 12.2-12.5 volts : WENT DOWN AND STOPPED AT 11.95 AFTER 30 SECONDS OR SO WITH LIGHTS ON AND KILL SWITCH ON.

3.) at idle (1500 rpm).....12.6volts - 13.2volts : 12.8 VOLTS

4.) at 2500 rpm 13.5 -14.0 volts : HOVERED AT AROUND 13.4 VOLTS

5.) at 5000 rpm.....14.0 -15.0 volts : VOLTAGE STARTED DROPPING OVER 3000 RPM, NEVER GOT HIGHER THAN 13.4.

6.) key off.....slightly higher than measurements # 1 (12.8-13.0 v) : YES SLIGHTLY HIGHER, NOW ON CHARGER.


So from your diagnosis summary it looks like my main problem is bad connections from test #5. I reckon the battery is probably fine and is just undercharged because of this. But I'll do this quick test a gain with a full charge to be sure.

Thanks again for the link Posplayr. I'm gonna hit the stator pages again too now and get this charging system better.

Which brings me back to the dyna S...???

When you go to the revised stator pages


Revised PHASE 1 of Stator Pages

In the Phase A part of teh test Step #2 you will probably find a high voltage drop between R/R (+) and the battery (+). High drops on the plus side come from the fuse box or the "T" connection where the R/R(+) and the Battery (+) come together in the harness. Also check the minus side.

I use a little acid 9Navel Jelly) and then flow some solder into the crimps to keep out corrosion.

The voltage drop to the coils is likely mostly due to the low battery. Charging at 13.4V is not much better than a trickle charger which will hardly recharge a low battery at all.

BTW, based on your measurements I know you are thinking the Dyna is causing the voltage drop as if there is something wrong with the Dyna. However there is probably nothing wrong with it. I suspect that you have resistance in your ignition switch/fuse box that you are noticing more now with the lower resistance coils.

[Coady]

The voltage drop to the coils is likely mostly due to the low battery. Charging at 13.4V is not much better than a trickle charger which will hardly recharge a low battery at all.

BTW, based on your measurements I know you are thinking the Dyna is causing the voltage drop as if there is something wrong with the Dyna. However there is probably nothing wrong with it. I suspect that you have resistance in your ignition switch/fuse box that you are noticing more now with the lower resistance coils.

Yeah I certainly was suspecting the dyna Ha .

Just did a couple more tests and it seems that voltage at the coils moved proportionally with rpm to the battery so it sat at around 11V at 2500rpm, about 2.5 V less than the battery.

I then ran a wire direct from the battery to the coil and there was only 1 volt difference. So I guess your coil relay mod is in order too!

I'll try and sort all this out on the weekend.

Thanks a lot for the help.

[posplayr]

Yeah I certainly was suspecting the dyna Ha .

Just did a couple more tests and it seems that voltage at the coils moved proportionally with rpm to the battery so it sat at around 11V at 2500rpm, about 2.5 V less than the battery.

I then ran a wire direct from the battery to the coil and there was only 1 volt difference. So I guess your coil relay mod is in order too!

I'll try and sort all this out on the weekend.

Thanks a lot for the help.

You mean this one?

http://www.thegsresources.com/_forum/showthread.php?t=141055&highlight=relay

[Coady]

You mean this one?

http://www.thegsresources.com/_forum/showthread.php?t=141055&highlight=relay

Yeah that's the one I came across earlier. Thanks for the detailed right up.

I was pretty irritated that new coils made it run worse . But it's all starting to make sense now! I'm so sick off looking at black plugs and scratching my head.