1989 25HP Mariner -- how does the ignition trigger work?

[SteveVT]

What does the ignition trigger head read? I know it doesn't read the outer flywheel magnets. It faces inwards.

So it must be reading something on the inner (shiny) part of the hub -- my question is: does anybody know what is in that band -- some kind of embedded magnetic spot (or spots) for the trigger to sense?

Thanks!

Steve

 

[flyingscott]

Pretty sure it does face outwards. The only magnets on that flywheel are on the outer ring

 

[flyingscott]

Sorry about that. It does face inwards and there is a magnet in the inside ring.

 

[SteveVT]

Thanks flyingscott, I appreciate your help. This is why I'm confused:

This is the inner hub - actually it is magnetic, it can hold a bolt pretty strongly upright Also it has a polished SS inner surface. Behind that, maybe you can see what might be a circular ceramic magnet. Then the rusty cast iron of the flywheel. That's a guess. I could definitely be wrong, and that's why I was asking.




Here is the inner face of the trigger housing. I think I see a silver looking pickup head in there.





Here is the outside face of the trigger housing. No pickup showing. Also the shape isn't curved like the stator or lighting coils faces. Wouldn't the cable on the left rub against the outer magnets if it were close to them? This is why I am confused re. the outer magnets activating the trigger.

 

[SteveVT]

Oops, missed your second reply -- so, okay that answers it.

My main reason for asking is because the outer magnets came loose, and I want to epoxy them back on. But I didn't know how critical their position was. I've looked at a lot of other flywheels to try to figure that out, and it finally ocurred to me that maybe the spark timing was set by the inner ring, not the outer magnets.

 

[flyingscott]

All the magnets are critical as far as placement goes. Where are you located

 

[SteveVT]

I'm in Vermont, flyingscott. I have found two photographs of magnet positions from the same year (1989) 25hp Mariner/Mercs. They seem to agree fairly closely (though not exactly) about magnet positions relative to the keyway and the flywheel ring gear bolt positions. I was going to use these as a guide. (More pics would be helpful.) Here they are:

 

[SteveVT]

Here's what I get for magnet locations from the first photo. 0.199" from the flywheel bolt hole location, measured along the inside face of the rim. And that should be 40 degrees from the center of the keyway.

 

[Faztbullet]

The inner hub is actually 2 magnets laid in a N-S S-N configuration that is the split you see in hub magnet.

 

[SteveVT]

Thanks faztbullet! I was thinking it was something like that, because as i moved the bolt around the hub there was a momentary change at the split.

Hmmmm. now things are getting confusing again. If that split is a trigger firing spot (which seems logical) then why is it in a very different location on the first flywheel photo than the second flywheel photo? (relative to the keyway)

The split on my flywheel is located in the same place as the flywheel #2, not flywheel #1. Both of these flywheels have the same part number. And that's the same part number as mine.

 

[SteveVT]

Would love to see any more pics of this kind of flywheel (magnet side) if anybody has any -- just to confirm where he split and magnets are. Maybe somebody moved them on one of these ebay pic examples. It's puzzling.......

 

[flyingscott]

Those flywheels fit a lot of years on that motor. Almost 20 yrs worth.

 

[SteveVT]

This morning I've found many more pics of flywheels of this type on Ebay. And even one of exactly the same year, and serial number series (0Cxxxxxx) as mine. They all have the inner magnet split in different places -- so that's not signifigant to timing.. They also may have bolt-holes for the flywheel ring gear in 2 different patterns locations, relative to the keyway: seems the olive green flywheels (earlier models) have them in one location, and the red flywheels (like mine) in another. One thing that seems the same in all of them is the position of the outer magnets, relative to the keyway. And that's what I needed to know in order to glue mine back in place with some confidence. I'll use the picture of the flywheel of the same year and serial # as mine as a guide for placing the magnets. Timing is adjustable by lengthening or shortening the ball ended rod that ties to the trigger sensor ring. The outer magnets should be within 16th inch or better using the photos, and I'll make sure they are equidistant apart. That's the best I can do.

 

[flyingscott]

I would just replace the flywheel they should be cheap as they are common. My 89 has a gray flywheel and the ring gear pattern is the same on all of them.