C40PLRU tach settimg 3P or 2P

[drewread]

Title says it all:

Should I set my Sierra Marine Eclipse Tachometer (Sierra Marine Eclipse Tach) to 3P or 2P setting for a 1996 Yamaha C40PLRU 2-stroke engine? I thought it should have been 3P, but the readings were very low... I switched it to 2P and I think they are closer to correct.. but am not sure.

Thanks for any advice you can provide!

[99yam40]

Did you not get instructions with your tach?

3 cylinder Yamaha C40 should be 6 pole
2 cylinder C40 should be 4 pole

At least that is what I see on here
http://faria-instruments.com/site_manuals/IS0086t.pdf

[drewread]

Sure,it came with instructions - which I read - and they suggested 3P for a 40hp Yamaha.. and made no mention of the cylinders.

You linked to Faria instructions (I don't have a Faria tach) and even they are unclear. They make mention of a C25 - 55 which may cover the C40 at 4 pole, but they also show a C/P/E 30-70 at 6 pole... image attached - see, clear as mud.

[boscoe99]

A 1996 C40 uses a 4 pole set of magnets to create electricity.

Number of cylinders used do not enter into the equation.

[boscoe99]

Sure,it came with instructions - which I read - and they suggested 3P for a 40hp Yamaha.. and made no mention of the cylinders.

You linked to Faria instructions (I don't have a Faria tach) and even they are unclear. They make mention of a C25 - 55 which may cover the C40 at 4 pole, but they also show a C/P/E 30-70 at 6 pole... image attached - see, clear as mud.

C25 - 55 is denoting a range of models. A C40 fits within that range.

[drewread]

A 1996 C40 uses a 4 pole set of magnets to create electricity.

Number of cylinders used do not enter into the equation.

Thanks Boscoe, that confirms that I chose the correct option.. What document did that come out of?

[boscoe99]

Top document came from a Yamaha tune up specifications book.

Bottom document was a snippet from the document that 99Yam linked us too.

[99yam40]

If you notice in the fiara link the C25- C55 2 cylinder motors are listed as 4 pole

The C30 - C70 3 cylinder motors are 6 pole

I have no idea how many cylinders your motor has, so that is why I posted what I did

[drewread]

Yes, I noticed that, in fact I pointed that out shortly after the link to the Faria manual was posted and mentioned that the whole thing was clear as mud.

[99yam40]

Seems you are having a hard time deciding how many cylinders your motor has or I am miss reading what you write

[drewread]

Seems you are having a hard time deciding how many cylinders your motor has or I am miss reading what you write

The number of cylinders don't have anything to do with the number of poles, otherwise the C30 would be a 4-pole and not a 6-pole... no?

I'm going with the information from the service manual regardless...

[99yam40]

OK I looked it up and your 1996 C40 motor has 2 cylinders

And the chart I posted shows that a 1984 and newer C40 with just 2 cylinders is a 4 pole

A 1984 and newer C40 with 3 cylinders has 6 poles

I do not see where the problem is with the chart

Now I could understand where the confusion would be when you have to decide between the 2 and 3 settings you listed