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General Category => General Discussion => Topic started by: guzziownr on April 18, 2025, 03:46:50 PM

Title: 1972 Eldo Tach with twin coils
Post by: guzziownr on April 18, 2025, 03:46:50 PM

 I put a 1989 engine into a 1972 Moto Guzzi bike. Everything works except the Tachometer because it was designed for a twin cylinder single coil bike and my engine is a twin cylinder dual coil model.

Basically the tach wants to see two pulses from the coil for each revolution and is seeing only one. I tried hooking up both coils with a diode inline to keep them from interfering with each other but I went from half-working to not working.

There are aftermarket solutions to this problem from the hot-rod world but I was wondering if there was something simple and cheap to fix this.

TIA, Guzziownr

Title: Re: 1972 Eldo Tach with twin coils
Post by: guzziownr on April 18, 2025, 07:15:05 PM

How about this?


(https://i.ibb.co/0gzcBXv/Tach-Adapter-1.webp) (https://ibb.co/0gzcBXv)

Title: Re: 1972 Eldo Tach with twin coils
Post by: Cam3512 on April 19, 2025, 04:17:17 PM

I thought Charlie would be here by now….

Title: Re: 1972 Eldo Tach with twin coils
Post by: Antietam Classic Cycle on April 19, 2025, 05:08:36 PM

Quote from: Cam3512 on April 19, 2025, 04:17:17 PM

I thought Charlie would be here by now….

I've never done it, so nothing to offer. Plus, it's already been discussed on the Loopframe FB group that I run.

Title: Re: 1972 Eldo Tach with twin coils
Post by: skippy on April 19, 2025, 05:42:44 PM

Quote from: guzziownr on April 18, 2025, 07:15:05 PM

How about this?


(https://i.ibb.co/0gzcBXv/Tach-Adapter-1.webp) (https://ibb.co/0gzcBXv)

Gawd, I miss having a Radio Shack around the corner.

Title: Re: 1972 Eldo Tach with twin coils
Post by: guzziownr on April 21, 2025, 05:29:06 PM

Quote from: Cam3512 on April 19, 2025, 04:17:17 PM

I thought Charlie would be here by now….

These are uncharted waters...