Speedo question

[cryin'wolf]

I talked to a Honda service mechanic, manager, and underwriter (what ever that is) at my local dealer, then a Honda representitve at their customer support line at 1-866-784-1870 said that the info I'm looking for is propietary. What I'm looking to find out is the pulse rate of the speedo sending unit that is attached to the front hub on the SS750. I believe it is a voltage pulse signal that is sent X# of times per mile. Does anyone know?

[AirportFF]

You might be better off trying to contact the manufacturer of the speedo sending unit (Honda more than likely subcontracts those out). Or maybe a company like autometer can point you in the right direction.

I think on the mechanical speedos it's 4450:1 or 2. Don't waste your time call Drag Specialties...you'll just get a "we make parts for Harleys" attitude

[RustyJake]

Couldn't you hook up a voltage meter to it and go for a drive, taking notes of the intervals?
I may be off-base with my thinking, the pulses could be too quick to monitor.

[AirportFF]

Along those lines. Instead of going for a ride, lift the front wheel and spin the tire a full revolution. Might work??

[cryin'wolf]

I could try it, if I can remeber to bring my damn multimeter home from work....

[croach1]

don't they tell you its propietary when the person you are talking to doesn't know the answer?

[fegs]

don't they tell you its propietary when the person you are talking to doesn't know the answer?


Croach, I think you are right. I never thought about it thinking that it was cable driven. Why dont you:
1. mark the ft. tire/wheel and lift the bike
2. Spin the tire and read the meter per wheel revolution

For the most part, the faster the wheel goes, the more voltage it will produde, much like a speed sensor for your ABS system on your car (if you have abs). The same for the speedo on your car.....

What is the purpose of your asking?

[fegs]

I talked to a Honda service mechanic, manager, and underwriter (what ever that is) at my local dealer, then a Honda representitve at their customer support line at 1-866-784-1870 said that the info I'm looking for is propietary. What I'm looking to find out is the pulse rate of the speedo sending unit that is attached to the front hub on the SS750. I believe it is a voltage pulse signal that is sent X# of times per mile. Does anyone know?


Re-reading your original post, I dont think the signal is produced by mile but by wheel revolution. Btw, it should be A/C voltage just in case your thinking of using a voltmeter.

[cryin'wolf]

Croach, I think you are right. I never thought about it thinking that it was cable driven. Why dont you:
1. mark the ft. tire/wheel and lift the bike
2. Spin the tire and read the meter per wheel revolution

For the most part, the faster the wheel goes, the more voltage it will produde, much like a speed sensor for your ABS system on your car (if you have abs). The same for the speedo on your car.....

What is the purpose of your asking?

I've contacted http://www.classicinstruments.net about making up a new multi guage with a tach for my bike but, they need the speedo info inorder to install the correct parts or calibrate it to the sending unit.

[Machinehead]

The company should have given you the name of the device's manufacturer...hitachi...yamaguchi or whatever,

BAD call on them....Are there any numbers visible on this device?



Not having any experience with your exact sitaution I could only try to best describe what is happening with a blind eye.

The pick-up/receiver is sending "pulses" at a certain frequency. The faster the frequency the more accurate the reading displayed on the OD.
The faster the rate the more accurate the display is with respect to the tach's accuracy.

In my mind this should happen with the engine running...sending out many "pulses" looking for the magnet or whatever else is embedded in the wheel that triggers the signal when the machine is moving.

So

The signal received from the sensor in the rotating wheel may be irrelevant as the signal used only displays the revolutions of the wheel NOT the actual characteristics of the pick-up. The pick-up should have a standard "pulses-per-minute" (I think this is what you're after).

...and using a DMM may only confuse you UNLESS you have a nice one that can read frequency...and you may need an ocsilloscope to get an accurate reading. As to whether how the scope leads are placed I would need a schematic, but my best guess is parallel....across the terminals.


Again...are any visible numbers or manufacturer data on this device....can you even see it..lol?

[cryin'wolf]

I spoke with Zac at Classicinstuments.com again. He told me they'd do all the leg work in getting the tech info they need. I'll get it from him ASAP, and post it incase anyone wants or needs it later.

Thanks,

[AirportFF]

That's a great idea. Post it up here so we can all have it. Thanks :happy:

I guess the meter and spinning the tire theory didn't work? :tired:

[cryin'wolf]

Okay, Here's what I got so far.... No help from Classic Instruments, the sensor is a Nippon Seiki, says so right on the thing. It has three wires going into it, which attach to a PCB Printed Circuit Board, which has a pick up coil and Frequency to Voltage converter. The hub turns a PM Permanent Magnet creating the pulse.

...So now here's the big question, how do I find the pulse per rev. if it's been converted?

[AirportFF]

Try conacting Autometer, they might be able to help with that.

Or you could call an electrical engineer :undecided

[Machinehead]

II'm no engineer, but I'd think that you're not on the right track with concerns about "pulses-per-rev" ..... even if you are able to read this output you will not get the info you're looking for....you will get the same data that is sent to the speedo.

The receiver is emitting a pulse at the freq. you are looking for > unknown-per-minute. Once the magnet makes contact the signal is interrupted and converted to a signal the speedo can use.

You are looking for the "characteristics" of this module....providing only a name is going to be tuff since this company prolly makes them all....numbers would be better. Something like ME9-000-000.

I wouldn't think that there is a common ground used for the 'outgoing signal' and the 'incoming signal' which is why I'd need a pinout or the characteristics of this device.....but....there may be a common ground....

Is the schematic you posted for your machine?

[cryin'wolf]

M-Head, yes the diagram is of the the SS750, and after discussing this with some of the avionic and electrical tech's at work, they came up with a solution to detirmine the pulse, which I will setup for in the morning. I'm going to reconnect all the stuff I've pulled apart, jack the front of the bike up and set the tire against a bench grinder with a buffing wheel on it, inorder to turn the wheel at a fixed RPM. Once I have a base line RPM of the wheel, I will pull the BL/Y wire pin out of the connector and connect it to the + side of a low voltage lightbulb with the other side to ground, and turn the wheel again for 1 minute and count how many times the light bulb flashes. Then it will become just another math problem. :no:

Say the base RPM is 100 and the bulb flashes 1600 times then the pulse is 16ppr. According to a Nippon Seiki product info site I saw earlier I know they only make 2, 4, 8, 16 ppr units, so at least that helps narrow things down. :Ghost_ani

[AirportFF]

Just wondering....how the hell do you intend to count 1600 times in one minute??? :happy:


Sounds good in theory, are you going to account for the buffing wheel slipping on the tire a little?

[cryin'wolf]

Really good questions AFF.... I'll pull the caliper off the rotor to reduce the drag on the wheel, I thought the buffing wheel would be better for my tires well being than a stone one. And as far as counting 1800 X in a minute..... I'll pray the unit is a 2ppr one or figure a way to slow the damn wheel down.... :stunned:
I'm fixin' to get started on that all now.

[cryin'wolf]

Okay, I'm totally stumped, I jacked the front up got the wheel rotating at a steady 58 RPM about 3 MPH. I had all the wiring connected in factory configuration, except for the black and yellow wire. I pulled the pins out of both connectors. I connected a low voltage test light to the end coming up from the unit and the - post of the battery. No light. No flashing. I put the light across the battery post to verify the bulb worked, it does. I checked the Speedo with the B/Y wire still disconnected, and it was registering 3 MPH. So I reconected the light through the B/Y terminals and there was still nothing. I reconected the B/Y wires and reppeated the same process with the G/B wire, and got the same exact results.

I'm stumped, by this because in my limited understanding of an interrupt circuit, there are 3 wires a source, a primary ground, and secondary ground, like a breaker point ignition system, there is one wire connecting the + Bat. to the coil + side, then one connecting the - coil side one side of the points, making the secondary ground, then the wire between the other side of the points to ground. When the points are connected, closed, the current takes the path of least resistance and goes to ground through the points, but when the points open the circuit is interupted and the current is forced to flow through the higher resistance of the coil to ground through the spark plug.

If this is correct I should be able to pick up a pulse through either the B/Y wire which according to the diagram is clearly the discharge lead (of the interupt circuit as I understand them), or the G/B primary ground that is being interupted.

Now that I've written all this out I'm thinking I'll disconnect B/Y and run the light between the G/B.

That didn't work either.... I quit! :furious2:

[AirportFF]

So your finally going to admit defeat on this huh? :wink_2:

[Machinehead]

"If you desire a cetain modification with enuff desire it can happen"

Author - me :)

Apologies CW for the late reply....and as I have read over the posts it seems that I have confused myself and thought that this was a tachometer issue and not a speedo issue which would explain my "confusing" post.


At any rate, do not follow my post in this thread except for the freq. parts.


Not having the schematic and trying the suggested test you're going to have to first determine if introducing more resistance into the circuit (ie ...the bulb) would affect any output signal.

Many times the voltage is reduced at or before some components and by introducing another element may....(for the lack of a better word) fuck'em up.


In retrospect you'll get a better reading using an oscilloscope or actually having the components characteristics.....



I see you've done the work....can you find the actual manufacturer's part number?

[Machinehead]

I want to add that in case you are unaware the electronic circuits are much more sensetive than the electrical ones.....many times....an electrical mishap will only blow the fuse where as an electronic fubar can fudge the device.

[cryin'wolf]

M- Head I think you are correct, in that the bulb offers to much resistence to the circuit, as it appears to opperate in the milivolt range, luckily I haven't screwed anything up yet. I'd just like to thank all who had any input on this, then let everyone know I quit trying to figure this out, and am contemplating using one of Classic Instruments sending units, which would likely require me to modify the front hub or rotor. However, I'm not sure I want to do that. :happy:

[RustyJake]

Don't they sell one with a magnetic pick up? That would seem the easiest solution without having to mod too much other then a bracket for the pick up. Not sure on what they use to generate their data to the unit itself. A few guys over at TSW run the Dakota Digital stuff, I think T-Rob even has that installed now. It may not be the look you are going for but he may be able to help with how he mounted their stuff.

[HSGear]

But really, who uses a speedo anyway? I'm much more of a trunks guy...