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Results 1 to 12 of 12
  1. #1

    Lightbulb Dwell/Tach Meter Wire Hookup?

    I have a '89 Johnson 50hp, 2 cyl, I cannot find in my manual or on the internet instructions regarding the correct hook up for the two wires from a "testing" tach to this engine in order to get the rpm for tuning low and high end.

    I have found different opinions (i.e. red to starter or hot, blk to grnd, and so forth), but as on older cars the distributor-to-coil offered the intermintant spark. This engine does not have points or dist.

    I am also wondering how a marine handheld "tach" is designed differently. I dont want to formulize an auto tach base on 8, 6, 4, etc. The manual shows a pic of one, 2 wires.... but that is it

    Who knows ?

  2. #2
    Join Date
    Jun 2011
    Posts
    202

    Default Re: Dwell/Tach Meter Wire Hookup?

    Look up Tinytach.Your auto dwell/RPM meter wont work on outboards or any 2 stroke.There is a way to drill a hole in the plate and hook up a OHM meter to set the points.I just set reinstall the flywheel and then use the timing light,if they are off I will redo them removing the flywheel.RPMs the tinytach works great! It reads sparks traveling through the plug wires,Each spark is one revolution.
    outboard tach measures??? I always forget either stator pulses OR ?????? someone will reply
    Last edited by dew2; 09-04-2011 at 09:35 AM.

  3. #3
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default Re: Dwell/Tach Meter Wire Hookup?

    This engine does not have any points.
    There are however some ways.
    Normally the outboard tach reads the charge frequency from the alternator system (6 pulses/rev)
    If you do not have an alternator type tach, you may use a multimeter set on HZ (frequency)
    Divide by 6, multiply by 60 (use the yellow/gray signal wire from stator. If your multimeter has an induction wire, coil it around one of the primary leads (still in HZ) and multiply by 60.
    If you have a timing light with built in rev counter, set it on 2-stroke or use 4-stroke and divide by 2 and you get the reading.

  4. #4

    Default Re: Dwell/Tach Meter Wire Hookup?

    I saw the Tiny Tach, cool idea, but a guy on Utube showed one then started having trouble reading the correct rpm,,,,,
    However, I cannot believe in my manuals it shows the Tachometer/Dwell as a common tool, but in neither the Clymer or Outboard Marine Corporation Service Manual does it explain how to hook up a Dwell/Tach. The J 50 doesn't have pts, but to tweak the timing an accurate rpm is needed, especial for high rpm. I have not found any answers to what a marine tach is vs the auto,, (and there is a difference), I would rather not go thru a rigged calculation -how about using the correct tool for the job, no offense- I just want to try the designed method first, ....I did find however, a description of using the gray wire from the T. Strip, for a tach and will try hooking up a test tach to it, but all this 4 cyl 6 8 auto is not my way of dependability.......anyone using a Tach/dwell meter to test rpm for timing and tune up?

  5. #5

    Smile Re: Dwell/Tach Meter Wire Hookup?

    Well, so far I did find an instruction to hook up the lead to the coil "high tension" wire. I am not sure what "high tension" means,....wire to plug or pre side?

    As the Clymer electrical schematic shows a gray wire running in this model for a tach, I do not have a gray wire on the T-bar. But I do have a gray wire running to the alarm via the thermostat -just a note for using manuals there are variations !!!

    But in addition, I also found out that a tach will run from the Number 2 terminal on the T-bar. So I am going to go with that.

    FYI: the Clymner has wiring schematics, the Outboard Association Servie Manual does not, however, it is far better for everything else mechanically and more....... I will post again after testing and tuning,,,I also need a test prop if anyone has one to sell.....1989 50 hp, Johnson.......thanks

  6. #6

    Default Re: Dwell/Tach Meter Wire Hookup?

    Yeah, I see what you mean, I replied abaout the # 2 screw on the T-bar, which is a yellow striped wire, I will double check,,,I dont have a multimeter with HZ reader, thats what I should have,...the calculations woould be the smae to just multiply by 10. But I think I see what you're getting at: divide 6 becasue there are 6 arms on the stator, multiply by 60 b/c 60 Hz???

  7. #7
    Join Date
    Aug 2011
    Location
    Germany
    Posts
    36

    Default Re: Dwell/Tach Meter Wire Hookup?

    Because on minute equals 60 seconds

  8. #8

    Talking Re: Dwell/Tach Meter Wire Hookup?

    Well I clamped onto the #2 T-post, (yellow stripe, Manual says gray ?) and no signal in the tachometer on on the multimeter while idling.

    However, as i try to idle by hear, the advance lever does not reset as far back as I can push it. This is while the idle and idle throttle lever is at a minimum. So I have this sruff at free fall right now, is there a visual trick in knowing where to have the advance lever linkage point while idling? Is this question confusing? I tired to post a picture, but didnt go though.

    As I move the advance leverage manually, the motor sputters and misfires, I know there should be a predetermined spot.

  9. #9
    Join Date
    Apr 2006
    Location
    , Langkawi, Malaysia
    Posts
    5,750

    Default Re: Dwell/Tach Meter Wire Hookup?

    put pic on Photobucket or similar and then post the link.

  10. #10
    Join Date
    Jun 2011
    Posts
    202

    Default Re: Dwell/Tach Meter Wire Hookup?

    Is there a idle stop screw on the throttle side of that motor? it may need backing off.That advance lever is to be set with the link and sync

  11. #11

    Default Re: Dwell/Tach Meter Wire Hookup?

    well this is my 4th attempt to get a photo, the forum keeps logging me off and says login.......I cant seem to figure out how to get a photofrom pbkt into the forum, The forum says to load jpeg, gif and etc, but Im not successful yet. Yes there is the idle screw, i have it recessed for the time being, as the manual says to, ( it is one of the last things to set).
    In a pic I want to show the space that the spark advance lever can move while linkage is set to idle, cam rod back and carbs in closed position. I think that the spark advance lever(rod) does not retreive all the way back in idle position-but Im not sure. I can set the engine to idle by hear, but its in the throttle up, i start to get cough and sputtering. My clest boat repair shop is 100 miles, they told me they do use a Tach, but adjust by hear......mm i can do that for idle but not wot. I hate to run it over there for them to try and set it by sound.........mmmmm not sure where Im going with this thread now......lol

  12. #12

    Default Re: Dwell/Tach Meter Wire Hookup?


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