Topic: Speedhut gauge tach signal

[Scott S]

 Here are the instructions that came with the gauge: http://www.speedhut.com/instructions/gps_dual_tach.pdf

 I have it wired up and I made a "Y" splitter and took the tach signal from the yellow wire from one coil. It seems to work, but doesn't seem to be getting the best signal. I tried 1 pulse per revolution but didn't like the response. I then tried 2 pulses and that didn't seem much better. It seems a little "sticky" and doesn't do much at all under 2,000 RPM.

 There was a resistor in the package, but I called Speedhut tech support and he said that was mainly used for ECU's. He said that if I had too much "noise", i.e., a jumpy signal, they have a suppressor or something. His reccomendation was to wire it up straight, which is what I have done. I don't think it's too "noisy", as it isn't swinging around all over the place. To me, it isn't responding enough.

 What would be the proper pulse per revolution for a digital tach taking signal from one coil on an SOHC4 engine?

[Nic]

I have speedhut gauges on mine, I made a splitter with vintage connections and hooked it up to the yellow coil wire, one pulse per rev is the correct setting on the tacho. Mine works perfectly. Maybe a dodgy ground connection?

[Scott S]

 Thanks. I'll check around. That's exactly how I have mine wired to the tach signal.
 One thing....I noticed that they said the antenna MUST be hooked up to scroll through the menu. Mine isn't hooked up yet (I'm going to mount it on the rear fender, just behind the seat) but I was still able to get to that menu.
 I don't really see how the GPS antenna should effect the tach operation, but maybe I should plug it in and see what happens?

 Might be a short while. I'm waiting for the fender to get back from chrome and I have to pull the carbs to check floats/needle valves to cure an overflow issue.

[Nic]

No the speedo doesn't effect the tach. They are totally independent. The antenna, I don't remember exactly but I do know the trip meter won't show until the satellite had been acquired and pretty sure the rest of the menu as well. Only the mileage shows without the antenna or before satellite is acquired. If you were able to access the menu without the satellite then I'll be forked? Maybe they've changed since I got mine a couple of years ago?

[Scott S]

 The headlight and tail light weren't even plugged in at the time. This is a '73 and has the single fuse.
 I didn't test charging in the brief time I had it running, but I did ohm out the alternator on the bench and it tested good.

[greenjeans]

I have those on mine.  It's an early 1 fuse harness.  Plugged straight into the coil (with a splitter)    The speedo should have absolutely no effect on the tach & vice versa.  It's just the one wire to the coils, a ground, and a hot for the gauge lights.   

I have the sender for my speedo under the gauges on the steering neck.  The long antenna wire routes back along the main harness and back up front - just to keep it from being a big bundle.  I did not wire the speedo to be "hot".   It easily finds the satellite signal in about 10 seconds.

Overall, I am VERY satisfied with them.  I've ridden in the rain (on accident) as well.  Before I installed them, I made sure that the rings holding everything together were tight.  From the factory, mine were loose and after a windy spring day outside, the gauges somehow had some pollen in them.

[Scott S]

 Speedhut added some silicone to mine since it's going on a motorcycle. I also had them shorten the lead for the antenna. I'll check my wires and ground.
 I'll be pulling the carbs soon to go through them again, so it might be a minute before I can test it again.

[Scott S]

 OK, so why do I have this lag? I emailed the video to Speedhut this morning. A friend said it's possible that it's picking up a 12V signal from something nearby and causing interference. I *DO* have it with the small bundle of wires right up by the tank rubber. The other coil wiring, horn, the key switch is nearby.  Think moving it away a little bit would help? Is there a way to "insulate" the wires from noise?

[greenjeans]

My connection for my tach is right by the coils and ignition switch, and is bundled together with the other coil wires, horn, and front brake wiring.  Plenty of things to make "noise".  i don't think that will be an issue so long as the insulation on your wiring is in good shape.  Any chance you could have a crack or bare wire in the bunch ?    Also, what shape are your spark plug wires in ?   Those, I think, would be more of a problem than the smaller wires.  If they are 40 years old, you could definitely have some cracking of the insulation right at the coils - that could bleed out some noise.   What kind of voltage are you getting when idling ?

[Scott S]

 Coils and wires ARE originals. They tested good and work fine, so I used them. I'll check for cracks, etc. Caps and plugs are new. The main wiring harness is new. Key switch and horn wires are original, but in good shape.
 Is that what it looks like to you? Signal "bleed through"? I have not checked voltage when idling yet. It seems a little "sticky" when revving, too.

[greenjeans]

To me it almost looks like something is cutting out toward the tach.  They should be rock solid (tach needle) - mine doesn't jump at all.  The wires speedhut provides are pretty thin.  Any chance you have a connector that is loose or ?  Double check your ground connections too

[Scott S]

 I can't find anything loose. I soldered the connections and then shrink wrapped them. Idle voltage is 12.7-12.9 and up to 13.5-13.7 at revs.
 Moving the wires aside didn't change anything.

[Scott S]

[Johnny5]

Scott,

Do you have the gauge 'hot wired' as well? If it isn't it'll take up to 5 minutes each time you turn on the ignition to find a signal. I have the tach/speedo installed on my bike. And it's pretty rock solid. On my CB350f, it's set at 1 pulse. The yellow wire for the tach splices right with the yellow or blue coil wire. Just one.

Sorry, didn't read all the thread if I added more info than is needed.

[TwoTired]

Plenty of things to make "noise".  i don't think that will be an issue so long as the insulation on your wiring is in good shape.  Any chance you could have a crack or bare wire in the bunch ? 

FYI: plastic or vinyl insulation is transparent for radiated emissions.  It there for contact insulation only.  Cracks won't let radiated the signals "leak out" anymore than the intact insulation.

Cracks in the HV leads can allow arcing, of course.  But, that is primarily a run issue.  Radiated emissions need a metal or conductive shield for effective blocking.

Just so you know.


Also, GPS receivers need time to find satellites and make correlations for positioning.  A delay in tracking is expected at power up.

Cheers,

[Scott S]

 I do have it hotwired. That's just for the GPS, though. At least that's my understanding. The signal for the tach comes straight from the coil and should have nothing to do with the GPS.

 Here's the reply I got from Speedhut:
 "Scott,
It looks like it may be getting a noisy ignition signal. What coils and wires are you using?"

 To which I replied: Stock coils and wires, new caps and plugs.

  Here's how I have it wired up. I am using a double female connector with a single make on the other end. The YELLOW wire from the main harness goes in, as well as the wire from the Speedhut tach. The other (male) end is plugged into the coil. All connections are soldered and shrink wrapped. Plugs are tight. The YELLOW wire with BLACK male plug is from the gauge.

[Johnny5]

Your yellow tach wire doesn't go to the black/white hot wire on the coil. Should splice in with the negative side. Cant tell by the picture if that's how it's wired.

I do have it hotwired. That's just for the GPS, though. At least that's my understanding. The signal for the tach comes straight from the coil and should have nothing to do with the GPS.

 Here's the reply I got from Speedhut:
 "Scott,
It looks like it may be getting a noisy ignition signal. What coils and wires are you using?"

 To which I replied: Stock coils and wires, new caps and plugs.

  Here's how I have it wired up. I am using a double female connector with a single make on the other end. The YELLOW wire from the main harness goes in, as well as the wire from the Speedhut tach. The other (male) end is plugged into the coil. All connections are soldered and shrink wrapped. Plugs are tight. The YELLOW wire with BLACK male plug is from the gauge.

[Johnny5]

Another thing to check for the tach, the lead from the gauge to the coil has a white connector in between. This is still connected tight?

[Scott S]

 No, it's on the yellow wire of the left coil.

[Scott S]

Another thing to check for the tach, the lead from the gauge to the coil has a white connector in between. This is still connected tight?

Yes.

[greenjeans]

Just for giggles...   Have you tried loosening the ring that holds everything together ?   Mine came loose.  When installed and riding, the face plate rotated just a hair.  I thought my clamp was loose and the whole thing was moving.  Those face plates do not have anything that locates them to stay in place.  The friction from the lock ring holds them.  Since you have 2 needles, that in effect, locates the plate, but there will still be some play.  Is there a chance that the plate has moved a tiny bit and is causing some binding on that needle ?
The wiring on the tach is sooo simple, it's hard to think it could be much else.

[Scott S]

 I called and spoke to William at Speedhut Tech Support today. I had sent him a video and some pics and went over again what all I've tried. He agrees that it's noise from somewhere and is sending me a tach filter. I'll get that wired up and see what happens.
 I have to say, Speedhut has been a pleasure to deal with, from the asking qustions phase, to building my gauge, to making the order and afterwards. Excellent customer service.

[Johnny5]

Totally agree on the customer service. William helped me with my GPS antenna. Top notch company top to bottom. Ill be buying all my gauges from them.

Hope you get your tach sorted soon. You'll love how smooth they are when it's up and running.

[greenjeans]

Still, double check the lock ring and plate.  If it rotated, even an amount that it's unnoticeabe, it could rub on that needle.

[Scott S]

Still, double check the lock ring and plate.  If it rotated, even an amount that it's unnoticeabe, it could rub on that needle.

 I checked....if you're talking about the ring that sandwiches it between the gauge holder. I didn't have mine that tight to begin with.

[Johnny5]

Yeah, mine worked with that ring being tight and loose.

Still, double check the lock ring and plate.  If it rotated, even an amount that it's unnoticeabe, it could rub on that needle.

 I checked....if you're talking about the ring that sandwiches it between the gauge holder. I didn't have mine that tight to begin with.

[Nic]

After 6 months or maybe a year, i don't remember but I wanted to change the faces on mine because the first lot I got had red numbering on black background and it was hard to see them so I wanted to get new faces with white numbers, they charged me for shipping only, no charge for the new faces. The needles being rock steady makes all the difference, not to mention that you know what speed you're really doing.