Tachometer interference
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Stellar HDF Member
Joined: Jan 2015
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From: ct
Tachometer interference
What would cause the needle to jump a little on my new tach, not a loose wire, not the tach cuz my old one did the same thing. 86 wide glide, Dyna S ignition. It's stable as can be at 3,000 rpm but below that is speratic. Something is is not right, size of the wire? Thinking outside the box.
Tourer
Joined: Dec 2014
Posts: 268
Likes: 69
From: Edgerton Wisconsin
Is it a factory tach or an aftermarket one? The aftermarket tach I put on my bike does the exact same thing. Its accurate from idle to 1500 but then just bounces all over until it gets north of 3k. I always just assumed it was a poor quality part?
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Joined: Dec 2005
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From: NC USA
I'm not saying this is definitely the cause - every time I've seen or heard of exactly that (1/2 dozen times maybe) the coil was going out. Happened to my '87, replaced the coil and no more issue. So I know it's a possibility but nothing is a given when it comes to electrical.
Is this a single or dual fire version of DynaS and if dual, are you using the original coil?
Is this a single or dual fire version of DynaS and if dual, are you using the original coil?
Tourer
Joined: Dec 2014
Posts: 268
Likes: 69
From: Edgerton Wisconsin
Ill be following along and I hope you get to the bottom of it. Hopefully it might shed some light on my same problem.
is your tach hooked directly to the coil or does your ignition have a tach sender wire?
is your tach hooked directly to the coil or does your ignition have a tach sender wire?
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Stellar HDF Member
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From: ct
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From: Poolville
Believe it or not I've seen poor stator output cause this issue as well doing AC test on your stator at idle should be around 13 to 16 volts AC and then do it at 2000 RPM should be 30 to 33 volts AC.. if that tests good check your voltage regulator..
But always check the coil as well 2.6 to 2.9 ohms on the primary side.. 10000 to 12,000 ohms on the secondary
But always check the coil as well 2.6 to 2.9 ohms on the primary side.. 10000 to 12,000 ohms on the secondary
Last edited by 98hotrodfatboy; Jun 2, 2023 at 11:28 AM.
HDF Community Team
Joined: Dec 2005
Posts: 5,374
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From: NC USA
I'm not saying this is definitely the cause - every time I've seen or heard of exactly that (1/2 dozen times maybe) the coil was going out. Happened to my '87, replaced the coil and no more issue. So I know it's a possibility but nothing is a given when it comes to electrical.
Is this a single or dual fire version of DynaS and if dual, are you using the original coil?
Is this a single or dual fire version of DynaS and if dual, are you using the original coil?
