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Discussion Starter #1
I'm considering two Martek coils on ebay. They are listed as 3 ohm coils. From what I have found searching this and other forums, 3 ohm coils are for breakerless ignition and 5 ohm coils are for the points and condenser ignition (which I plan to keep for the time being). Could someone please either confirm this or let me know if these coils would work with my stock ignition?

Thank you.

RVC
 

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Discussion Starter #3
My bike is a 74 Z1. I don't have a problem. I'm just considering replacing the stock coils with a set of aftermarket coils.

RVC
 

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I ran a 3 ohm Accel coil on my 750 twin with points, and continued running it after upgrading to electronic ignition.

You don't want to leave the key on with the bike not running though, you'll let the magic smoke out of the coil.

You can run 3 ohm coils in place of 5 ohm coils by using a ballast resister.
 

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If you run 3 ohm coils with breaker points, you can expect the points to pit much quicker - but you will get a slightly better spark doing this.

If you plan on switching to an electronic ignition in the future, then go 3 ohm coils. If you plan on keeping points, then I would recommend 4 or 5 ohm coils.

We (and others) sell a good selection of new coils for the Z1. These include 4 ohm OEM style coils, and Dynatek 3 ohm and 5 ohm coils - prices range from $70 for a pair to $125 for a pair.

Martek was a good name 20+ years ago, but they are going to be very old coils - it's been a long time since I've seen new Martek coils... and assuming they are used, you may or may not get a good set.
 

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Discussion Starter #7
Thanks Steell and Jeff. Good info there, and I think I'll just stick with the stock coils for now. I'm trying to bring my old Z1 back to life after it has been in storage for 16 years. I'll come back to a hotter ignition later after I see if the old girl will actually run again.

RVC
 

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Obsessed by Z1's
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One important thing to check is the voltage at the coils.

With a fully charged battery in the bike, you should see 12.5v or slightly better when you check the voltage across the battery terminals. If you check the voltage at the coils (yellow/red is the switched power) back to the battery, you need at least 11v - ideally 11.5v or better. On many of the old Z1's, you can see voltage as low as 9v - and when you put so little juice into the coils, you will get a very weak spark...

Cleaning all the electrical contacts may help get it back within range, but if not, there's a fairly simple relay installation that will guarantee good voltage to the coils.
 

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Discussion Starter #9
Thanks for this. A battery will go in soon and I'm at the stage now where I'm checking the wiring and connections. Desired voltage range is a good thing to know. I'm familiar with the "wiredgeorge" relay approach, if that is what you are referring to, and I plan you use it.

RVC
 

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Martek old school

I had an old 750 K model that had the old Martek electronic conversion on it. Bought the 3ohm (green) and the Dyna S for my new old 76 KZ900, did the coil relay thing and man with the electronic it has a super strong spark. Now if I had the head back I could go riding.
 

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One important thing to check is the voltage at the coils.

With a fully charged battery in the bike, you should see 12.5v or slightly better when you check the voltage across the battery terminals. If you check the voltage at the coils (yellow/red is the switched power) back to the battery, you need at least 11v - ideally 11.5v or better. On many of the old Z1's, you can see voltage as low as 9v - and when you put so little juice into the coils, you will get a very weak spark...

Cleaning all the electrical contacts may help get it back within range, but if not, there's a fairly simple relay installation that will guarantee good voltage to the coils.

if i try the coils power.. i realized that I put a tip of the tester to the wire yellow / red, but the mass where it is better that I take? anywhere on the chassis frame?

sorry for english :oops:
 

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Discussion Starter #12
No need to apologize for the English there Cucco. You're doing a lot better than I could with Italian.

If I understand your question correctly you are looking for where you should touch the negative probe on your multimeter. Probably the best place would be the negative terminal on the battery. Any place on the chassis should work assuming you have good contact with metal there and the connection between the battery and the chassis is good.

All the best.

RVC
 

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If you want to get a "true" reading of the power at the coil, disconnect the + wire from the coil then use the the ends of the + and - wires as your test point. There could also be some voltage loss from the ground side just like the + side.
 

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Discussion Starter #15
If you want to get a "true" reading of the power at the coil, disconnect the + wire from the coil then use the the ends of the + and - wires as your test point. There could also be some voltage loss from the ground side just like the + side.
The only problem with this is the coil ground goes through the points. If the points are open there will be no reading as the circuit will be open. Unless I am missing something...

RVC
 

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If the points are open there will be no reading as the circuit will be open. Unless I am missing something...

RVC
That is a big "if" considering the amount of time the points are open during the rotation of the engine but in your case you have a kick starter so it's an if that is easily corrected.
 
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