Electronic Tach

[wirespokes]

The electronic tachs are known to be failure prone. I've 'killed' a couple and want something a little more robust.

I've thought of replacing the movement with another - but the ones on ebay tend to be for cars with 4, 6 or 8 cylinders. It would be nice to keep the original face to keep the look.

The ones that will work on two cylinders tend to run in the couple hundred range up to three hundred.

I'm thinking I'll need a tach able to read a one cylinder engine - considering it will hook up only to one coil. Am I thinking this through correctly?

So, I got a bright idea - why not get a Harley tach? Is there any reason that wouldn't work? They're pretty cheap on ebay. But I don't know how the Harley ignition works.

What do you think?  Will it work? Problems?

[Dr. Enzo Toma]

What specifically are you installing it on?

Harley tachs vary. Older carbed Harleys mostly have a dual-fire/wasted-spark ignition (the po-ta-to sound 🥔) while newer EFI Harleys are single-fire.

[faffi]

Good quality electronic tachos last "forever". There are far more parts to wear and fail in a mechanical tacho. If you buy a 10-dollar instrument from China, there is a risk it will fail prematurely. Especially if it is made for use in a car, since it will not be water-resistant. An electronic Harley tacho will be of good quality, but with a single coil firing twice per revolution I expect it will not perform correctly on a Guzzi.

[paulbricey]

Harley ones may be specific to Harley spark patterns (probably that they just configure them for Harleys), but I know the market generics are completely configurable for different cylinder/spark combos https://www.smiths-instruments.co.uk/app/uploads/2023/05/pil60a-cai-mcycle-tacho-356.pdf  I still have an eye (sadly not a wallet) on a pair of Smith clocks for V50 if oem ones ever fail although 150 mph top end is a stretch on V50.

[snobear]

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I installed speedhut gauges, electronic tach and GPS speedo and they are working fine.  The tach hooks to one coil only.  I installed the Speedhut units in the old cans

[Kiwi_Roy]

I also like SpeedHut electronic gauges, they will allow you to design your own colours, font etc and will even do a Guzzi eagle graphic.
They come with a pushbutton to configure them, get the one that plugs into the back not the one mounted in the glass as it's not waterproof.
www.speedhut.com

[PeteS]

This is what I used in my EV. It was calibrated for one pulse per revolution so I hooked it up to the coil primary which also gets the wasted pulse from the other side. Made a new dash to accommodate the larger gauge.





Pete

[wirespokes]

I wouldn't have thought of that, Pete. Thanks for the tip!

[dguzzi]

    Love to see how you went about making that new mount, Mine are both still working but I keep expecting to have to change them.
 I like the look of the Autometer white face.

[PeteS]

    Love to see how you went about making that new mount, Mine are both still working but I keep expecting to have to change them.
 I like the look of the Autometer white face.

I just took some aluminum plate, 3/32”, 1/8” ?? Been a few years. Then just used the original and scribed around it making the section for the gauges a bit larger. Cut it out with a band saw and hole saw and then used a heavy sheet metal brake that I had at work to make the bend. Both gauge holes were cut for the larger gauge and ring made to support the stock gauge thinking eventually I would have to get a new speedo. I think I bead blasted it and then coated with clear to prevent tarnishing.

Pete

[Turin]

Speedhut is the way to go. they are good for everything from singles to 12 cyl. I got a little fancy with mine.
https://www.youtube.com/watch?v=RmflHQ0B9og

[dguzzi]

   Thank you Pete!
  The Speedhut ones are great too.
  That would be a good project for in case I run low on projects!