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How to set WOT on 1990 evinrude 100

Rhigley

Member
I'm looking into checking the WOT setting on my motor. I changed out the prop but they look to be about the same but I get a reading of over 6000 rpm when WOT is set. Other than prop and throttle is their another way to keep the motor from over reving?
 
I'm looking into checking the WOT setting on my motor. I changed out the prop but they look to be about the same but I get a reading of over 6000 rpm when WOT is set. Other than prop and throttle is their another way to keep the motor from over reving?

The important thing to keep in mind is that the "Full Spark Advance" setting must be "exactly" what your service manual states... and No, I have no idea what that should be. If it is not set properly, you will encounter "Pre-Ignition" which will result in damaged (melting) pistons.

With the above in mind... matching the propeller on the engine with whatever boat you have (hull resistance) would be the only way to keep the engine's rpm slightly below the "Top WOT Rated RPM" that the engine must not exceed.
 
Ok. the book says 28 deg. Can I set this with a timing light and grounding all 4 leads with the switch by-passed or should it be in the water running WOT ? I have not been able to check this because I need a new fuel pump because it starves after about 30 sec. on the water.
 
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Ok. the book says 28 deg. Can I set this with a timing light and grounding all 4 leads with the switch by-passed or should it be in the water running WOT ? I have not been able to check this because I need a new fuel pump because it starves after about 30 sec. on the water.

You can check or set the timing via the following method... BUT........

If that engine has the "Fast Start" feature (and I think it does), you'll need to disable that feature first. Another member will need to tell you how if you don't already know.
********************
(Timing At Cranking Speed 4°)
(J. Reeves)


NOTE: If your engine has the "Fast Start" feature", you must disconnect/eliminate that feature in order to use the following method. The "Fast Start" automatically advances the spark electronically when the engine first starts, dropping it to normal when the engine reaches a certain temperature.

The full spark advance can be adjusted at cranking speed,"without" have the engine running as follows.


To set the timing on that engine, have the s/plugs out, and have the throttle at full, set that timer base under the flywheel tight against the rubber stop on the end of the full spark timer advance stop screw (wire it against that stop if necessary).


Rig up a spark tester on the #1 cylinder plug wire. Hook up the timing light to the #1 plug wire. Crank the engine over and set the spark advance to 4° less than what the engine calls for.


It's a good idea to ground the other plug wires to avoid sparks that could ignite fuel that may shoot out of the plug holes. I've personally never grounded them out and have never encountered a problem but it could happen.


I don't know the full spark advance setting your engine calls for, but to pick a figure, say your engine calls for 28°, set the timing at 24°. The reasoning for the 4° difference is that when the engine is actually running, due to the nature of the solid state ignition components, the engine gains the extra 4°.


If you set the engine to its true setting at cranking speed, when running it will advance beyond its limit by 4° which will set up pre-ignition causing guaranteed piston damage! You don't want that to take place.


No need to be concerned about the idle timing as that will take care of itself. The main concern is the full advance setting.

A fellow member from one of the various marine forums suggested having water supplied to the water pump (flushette or barrel) simply to provide lubrication to impeller. A worthwhile suggestion I thought, and entered here.


Be sure to use your own engines spark advance settings, not the one I picked out of the air here in my notes.
 
what if I ran the motor for a bit to warm it up before I set the timing. Would that eliminate having to by pass the fast start?
 
Look at the heat sensor wires leading out of the cylinder heads. If one of them (the port bank) has two wires leading from it, it would have Fast Start.

If there is only one wire leading from both sensors = no Fast Start feature.
 
not sure I have all the info I need. Do I disconnect the remote cable from the fuel side and then place spark advance all the way foreword or do I need to bypass some electrical switch to let the starter motor to engage?
 
not sure I have all the info I need. Do I disconnect the remote cable from the fuel side and then place spark advance all the way foreword or do I need to bypass some electrical switch to let the starter motor to engage?

Mechanics use a push button start switch connecting one lead to the battery cable side of the starter solenoid, with the other lead connected to the small 3/8" nut terminal of the solenoid that engages the solenoid to energize the electric starter... or you can simply use a small jumper to do the same thing.

However... Uh-Oh..... In checking my books, that 1990 100hp model has the mechanical slotted arrangement for the full spark advance and DOES NOT have the rubber stop cap as mentioned in the setup above (reply #4). As such, it would be better to check the timing normally, under way at full throttle.
 
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