Dying Coil on a GS1100E

[TomE]

So I am looking for a coil, or given the age of the bike, two coils. Any advice on good deals, used parts, and so forth? And should I really replace both, on the theory that if one is going, the other must be close?

I have put details below for those of you who are interested.

Thanks!

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I have been resurrecting a garage find GS1100E that I bought from a friend of mine. He has owned it since new. For a bike that has sat for the last 20 years, it's in pretty good shape.

I thought I had it running this morning and set out to ride it to California. That did not work out so well. Within 30 miles of home I was dropping power so much that I was in the right lane looking for an exit. I got it home and later, after a cooling off period (me, not the bike!) I took a look to see what was happening.

I have high impedance on the right side coil, across the two plugs. About 150K Ohms on my old Ohm meter, although wiggling things can adjust the reading a bit. The other coil measures 35k Ohms, which is more like it. Both coils measure 5 Ohms across the input leads. Also, if I disconnect the low voltage side of the right coil, the bike actually runs smoother. No stumbling, but it is running on 2 cylinders, not four.

Finally, at idle, I put my DC voltmeter across the input to each coil. Both read 4 volts. Given that the signal is pulsed, and a DC voltmeter will average the pulse, that means that both igniters are working. The voltmeter is working sort of like a dwell meter in this application.

I wondered if I had a flaky connection to the plug sockets, so I took that joint apart and cut a half inch off the end of the plug wires and reattached the plug sockets. No joy.

Looks like I need a coil.

 

[terrylee]

Go to Basscliff's site on here, and it will tell you how to test most of this and what your results should be. It maybe something as simple as bad, loose or corroded connection on the bike's wiring. Clean up all connections and do the tests. terrylee

 

[rapidray]

Keep in mind you have a 30 year old bike. Yes, change the coils & plug wires & with the Dynatek 3.0 ohm green coils & new wires the bike will run better. I am a dealer for them if you need parts. Ray.

 

[TomE]

Yes, the bike is 30 years old, like you say. And the more parts that are new, the more reliable it is likely to be.

Dyna? I would like to go Dyna, but that 3 Ohm primary worries me. I measured 4.7 Ohms on the primary of my stock coils. I would not want to put a coil on there that drew too much current and fried my igniters. Those igniters are not cheap either!

Will the Dyna 3.0 Ohm coils work with the igniters, in your experience? Or should I get a couple of 1.7 Ohm ballast resistors to put in series with the Dyna primaries?

 

[rapidray]

The green 3.0 ohm coils are the ones Dyna recommends for the 1100s. At least for the 16 valve 1100s. Is yours 16 valve or 8? Ray.

 

[mike_of_bbg]

Maybe a dumb question, but have you checked your plug caps? The resistors inside of them can go bad and jack up the secondary impedance. I just tossed one that was about 150k on its own.

 

[TomE]

Hi Mike,

Not a dumb question at all. My '75 wing has those pesky resistors, but I had forgotton that the GS might have them.

And to make matters more interesting, the resistor, contacts, and the spring were all corroded. So that's the problem.

I don't need a coil at all!

So thanks for the dumb question, you fixed a dumb problem on my end!

This is why the board is so great!

 

[TomE]

So my 16 valve GS1100EX takes the NGK XB05FP spark plug cap. That's a $4 cap instead of the OEM cap, which is in the $14 to $19 range. And the OEM cap is likely also NGK.

Not bad. I was looking at a couple of coils and more than $300. With a few ideas and Google, it's down to under $30.

Nice. Thanks guys!

 

[mike_of_bbg]

It's always nice when it's something simple (and cheap)

I thought one pair was XB05F and the other was VB05F (see http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A02 ).

Now let's just make sure it fixes your problem when you replace them. Don't forget to trim off 1/4" or so of the wire so you get some fresh copper to screw the new plug caps into.