1976 GL1000 Switching to GL1500 coils and using points setup

[flyin900]

I am looking at switching out a very old set of Dyna coils that I feel are no longer performing well (1970's vintage Dyna's). This setup is using the original OEM points and a 1.5 ohm ballast resistor in the circuit.
I have a set of GL1500 coils and would like to wire these into the bike while still retaining the original points set up, yet I plan to remove the ballast resistor and run the coils like a more modern Honda CDI ignition.

Any experience using these GL1500 coils with an original points set up and no ballast resistor?

[ericheath]

Just looked at the manual and one page says the coils are 3ohm and two pages later it says the ballast resister is 3ohms also.

Randall has a good write up on them. My memory is telling me the 1000 coils were two ohms. But it’s a bit fuzzy.

[ericheath]

Just checked his site, coils are two ohm, ballasts are 3ohm.

http://www.randakksblog.com/?s=+Coil+testing

So gl1500 are about 3ohm. Using a 1.85ohm Chrysler ballast resister would make them similar.

[flyin900]

I have an old 3 ohm Dyna coil set on there and a 1.5 ohm ballast resistor (non stock). I am also running the Hondaman points box which is a switching device that turns the points into triggers for the box. The benefit is the points see no electrical feedback like normal, so they last much longer without the arcing issues.
My desire is to get rid of the reduced voltage to the coils under the run condition where the stock ballast resistor reduces the voltage to about 9 VDC to the coils. The original Honda coils are designed to operate at these 9V voltages correctly, yet the GL1500 coils may not produce proper output with reduced voltage.
I will keep the Hondaman box in place, so the points will be protected from electrical feedback from the system.
I find the current setup on the GL1000 is producing a weaker spark than the GL1100 I am presently restoring. The spark is noticeably weaker when I have compared the two spark plug outputs.
The GL1000 is harder starting now than when I first built it, especially after I have let the bike sit for a week, or when I stop for gas and do a restart after the fill up.

[Track T 2411]

IIRC, Mike Nixon advocates removing the ballast resistor and running the stock coils at full voltage. You'll find the discussion in his Wing Tip #6...

[flyin900]

Thanks Track,

I am reading through some of the other posts related to this subject and Mike is high on my list of trusted "experts" on these bikes. I will check out his post and I am doing some further tests as suggested to see what the voltage is at the coils under run conditions with the current set up.
The bike still runs well overall, yet I am not satisfied with the start issues and idle set up, which maybe not ignition related. So one thing at a time and ignition is the current project to verify. Then on to tuning the idle mixture and carb resync.

[flyin900]

OK I didn't end up changing the coils, as I did a lot of testing of the original setup and found a couple of issues. One of the NGK spark plug caps was flakey with intermittent resistance readings. These were brand new a few years back, so something gave out on the setup. The aftermarket ballast resistor on one end the connector wasn't solid and broke off when touched.
After correcting these issues with a new NGK cap and soldiering a new terminal on the ballast resistor I proceeded to check out the specs and voltages per Randakk's checklist.

With the headlight disconnected from the electrical system and the bike not running I was reading 11.9V on the input side of the ballast resistor and 9.8V on the output side. The coils were 3.2 ohms on the primary side without the ballast resistor in the mix and 19.7 K ohms on the secondary side with the NGK spark plug caps in the measurement. So 10K ohms of the measurement would be from the resistor NGK caps and 9.7K ohms the secondary windings of the Dyna coils.

The bike actually started quite quickly from the winter layup without any fuss. So with the bike running test I was getting 14.4 V on the input side of the ballast resistor and 12.5 V on the output side of the ballast resistor at approximately 1200 RPM at idle. The spark at the plugs looked pretty healthy overall, so I am going to give this a go and see how it performs over the start of the riding season.

I did previously reset the valve lash to .006 per Mike Nixon's recommendation. I also adjusted the air mixture screws on the carbs to 3 turns out from the factory 1.5 turns. I did a carb sync today which was already pretty close overall, just some minor fine tuning was all that was needed there.

YAY.