Tachometer Calibration

[BigNiner19]

So I hooked up a tachometer, because running a 2 stroke without one just doesn't make much sense to me. I got a nice Tachometer from a boat I bought, and decided to use it for a different boat of mine. The gauge is a TuroTest RPM Gauge. Pretty nice gauge really.

When I hooked it up to the boat, it was pinned at about 2100 RPM's at nuetral idle position, on my boat. No shot that my motor is idling that fast. At best my motor MAY be idling 1000 RPM's. The gauge was previously used on a 115 2 stroke Yamaha, and I'm trying to use it for a 60HP 2 stroke Johnson. Is there some kind of calibration, or adjustment that I would need to do to make it work? I dont see much to adjust on the back of the tach.

Cory

 

[guy74]

Re: Tachometer Calibration

Hi Cory,
There should be a dail on the back of the tach. You need to set yours for a 12 pole altenator. The setting on my teleflex tach is 6p (pulses) for a 12 pole alt.
Have a good day,
Brian

 

[HighTrim]

Re: Tachometer Calibration

More info for you

http://ww2.tflx.com/PDF/99320.pdf

 

[BigNiner19]

Re: Tachometer Calibration

Hi Cory,
There should be a dail on the back of the tach. You need to set yours for a 12 pole altenator. The setting on my teleflex tach is 6p (pulses) for a 12 pole alt.
Have a good day,
Brian

Man I wish they had a some kind of setting like that on this gauge here is a picture of the guage. Let me know what you think. There is a hole just above where the 12V wire connects, but I can't really see what is down in there.

Cory

 

[HighTrim]

Re: Tachometer Calibration

Tachometers read off the alternating pulses from the stator. Any of the leads from the stator charging portion can be used for the signal. The designated tach signal wire is merely attached to one of those. Tachs have rotary switches on the back that set it to different numbers of coils in the charging circuit, times two because there is a positive and negative pulse for each coil for each cycle. Tachs measure pulses. That being said, you need a tach that has the setting that you need designated on the rotary switch.

The BRP tach of the right model comes with a harness that you can plug and play. The Teleflex tachometers offer the harness as well.

http://www.iboats.com/Teleflex_Tacho...-view_id.40245

Or you can easily wire most tachs, that have the correct settings on the rotary dial of course, by either going directly to the ignition switch or by cutting into the main harness.

That being said, I do not believe that you can use that tach for your outboard.

 

[BigNiner19]

Re: Tachometer Calibration

Tachometers read off the alternating pulses from the stator. Any of the leads from the stator charging portion can be used for the signal. The designated tach signal wire is merely attached to one of those. Tachs have rotary switches on the back that set it to different numbers of coils in the charging circuit, times two because there is a positive and negative pulse for each coil for each cycle. Tachs measure pulses. That being said, you need a tach that has the setting that you need designated on the rotary switch.

The BRP tach of the right model comes with a harness that you can plug and play. The Teleflex tachometers offer the harness as well.

http://www.iboats.com/Teleflex_Tacho...-view_id.40245

Or you can easily wire most tachs, that have the correct settings on the rotary dial of course, by either going directly to the ignition switch or by cutting into the main harness.

That being said, I do not believe that you can use that tach for your outboard.

Thats how I wired it up. It had a plug, but i took the plug off and wired it directly together using butt connectors. When I moved the throttle to move the RPM's up some the Guage seemed to respond like it should, it just would only idle at 2100 RPMS. I really can't see my motor idling that fast. It would have blown up by now with all the idling I do.

So I guess this gauge was just meant for a yamaha 2 stroke like it came from or what? I figured any aftermarket gauge would work. Weird that it does work a little, but says my idle is so high.

Cory

Cory

 

[guy74]

Re: Tachometer Calibration

Have you looked up TuroTest gauges on the internet? I looked in their online catalog, couldn't find an altenator driven marine tach, just tachs that used a magnetic sender. I'm stumped, not much info on their website.

 

[Randyg123]

Re: Tachometer Calibration

I don't know the Yamaha engine numbers but if you look at this site

http://faria-instruments.com/downloads.php

On the bottom of the last page, they show the Yamaha engines and how many poles their alternators have (4,6,12). It looks like your Yamaha engine should be a 12-pole. I may have missed something on your Johnson engine but I didn't see a year, just that it was a 60HP. From the Faria catalog you can see that the 60HP three cylinder is a 12-pole. But the older 60HPs that are two cylinders, are 10-pole alternators. The Faria chart says 1985 and newer three cylinders, but I think the 1985 was still a two-cylinder or maybe a crossover year (not sure).

I couldn't find your tach on Turo's website but it appears they have two types of tachs. An alternator style (uses pulses from the alternator) or one that uses a sending unit. On top of that your tach does not appear to be adjustable. So if this is an alternator-style tachometer from Turotest and it was a twelve-pole type working on your Yamaha, then it should work on a 12-pole Johnson. You have to look on Faria's chart to see what pole alternators each of your motors (Yamaha and Johnson) have. Then see if the tach is even compatible.

If both engines have the same number of alternator poles and assuming the Yamaha was reading correctly, then the RPMs should have read correctly on the Johnson. Otherwise you have a problem with your tach signal on the Johnson and should go through the rectifier troubleshooting posts under "Engine FAQs" found on this site.

If the two engines do not have the same-pole alternators, then the Turo meter would be useless on the Johnson.

If it is a sender-type tach, I have no idea what to do.

Hope any of the above info helps.

 

[BigNiner19]

Re: Tachometer Calibration

Thanks for the help. Looks like I can't use this tach with my Johnson.

My Johnson is a 1991 60HP by the way.

Cory