Tach setting?

[pokman]

Anyone know what the proper setting for tach would be? I have a 94 125 outboard. It's set a 6 right now just want to double check thats right. Thanks

[scooper77515]

6 is correct if it is a 6 cylinder engine. 4 if a 4 cylinder, etc.

[Chris1956]

No, the tachs work off the alternator. They do not care how many cylinders the motor has, unlike a car. Most Mercs use a setting of 6.

[scooper77515]

But then arent most mercs 6 cylinder?

I may be thinking of the wrong settings. Mine has a switch that i can change depending on if it is hooked to a 4 cyl, 6, 8, or 12 cyl engine.

[pokman]

Mine has 4 options 4, 6, 10 and 12 it was pointing at 12 which I thought was wrong. I figured 6 or 4. It is a 4cyl.

[scooper77515]

Just for sake of argument...flip it to 4 and see how it works.

My simple logic says flip it to the number that corresponds to the number of cylinders you have.

Worked for me. Mine has 6 cyls but was set at 8. Said it idled at 450 and maxed out at 3900. Flipped switch to 6 to match cylinders and now idles at 600 (where it is supposed to) and redlines at 4800 (where it is supposed to).

[pokman]

I actually already winterized it so I can't take it out. But I talked to a merc service guy today and he said it should be set a 12, so I guess it was right anyway. I was just wondering because with a 21p prop on my boat wot is at like 5400 and it my range is 4800-5200, so I don't know why with a prop with that much pitch I'm going over?

[Chris1956]

Hey Scooper, your logic is incorrect. Merc makes 2,3,4 and 6 cylinder motors. They share tachs and several models share tach settings. This is possible since the tachs count the number of pulses from the stator, to determine RPM. 4 and 6 cylinder motors for example, share charging coils in their stators, so they use the same settings.

[scooper77515]

My experience is from automotive tachs, and the one in my boat looks just like them. Glastron 2003 model.

It has a switch at the back that corresponds with the number of cylinders in the engine, just like the ones in my cars.

[bhile]

The one in your Glastron would look like an auto tach. You have an I/O and he has an outboard. The tachs work differently like Chris said. The most common setting for an outboard is 6P (pulses) which comes from a 12 pole stator.

[scooper77515]

oh. Sorry if I confused anybody. But at least my inaccuracy led to learning something new