Trying to calibrate new tach

[DestinII]

Hi Folks, I have a 1982 Fisherman 204 that I just purchased this year with a 2000 Johnson 130. The engine "seems" to be idling normal around 700 rpm but a brand new Teleflex tachometer is registering between 1300 to 1400 rpm. The unit has an adjustment screw for "fine tuning". I have a very good automotive type engine analyzer that I could use. Question is can I connect the engine analyzer to the gray tachometer wire and have both give a reading?

Thanks in advance for your comments.

Destin II

 

[seasick]

Hi Folks, I have a 1982 Fisherman 204 that I just purchased this year with a 2000 Johnson 130. The engine "seems" to be idling normal around 700 rpm but a brand new Teleflex tachometer is registering between 1300 to 1400 rpm. The unit has an adjustment screw for "fine tuning". I have a very good automotive type engine analyzer that I could use. Question is can I connect the engine analyzer to the gray tachometer wire and have both give a reading?

Thanks in advance for your comments.

Destin II

Sounds like the tack may be set for a four stroke and not a 2 stroke. If so it will read twice the actual revs.

I also suspect that the analyzer if it is one that clips onto the spark wire can be attached at the same time but even if it cant, use it without the tack to measure the revs and then swap the tool for the tach and compare.
I would not touch the adjustment screw for now.

 

[DestinII]

Thank you Seasick. Good advice, I am pretty sure I set it for 6 pulses but I will double check that. As far as the engine analyzer it is not the spark plug clamp type (it is older) has the 2 alligator clips for the coil. I know I can not connect to the coils on a 2 stroke but I think the post in the back of the tachometer where the gray wire is might do it.

Again thank you.

 

[seasick]

Thank you Seasick. Good advice, I am pretty sure I set it for 6 pulses but I will double check that. As far as the engine analyzer it is not the spark plug clamp type (it is older) has the 2 alligator clips for the coil. I know I can not connect to the coils on a 2 stroke but I think the post in the back of the tachometer where the gray wire is might do it.

Again thank you.

One doc I looked up says that Johnson motors over 75HP have 12 poles. That would explain the 2x reading

 

[DestinII]

That is correct but it is 12 poles - 6 positive and 6 negative. That is why the largest setting is 6P. Anyhow, I tested it tonight and the analyzer said 680 rpm at idle which is fine while the boat tach was at 1400 rpm
I hope that adjustment has a lot of play in it. But first I need to find out what is draining my battery. Oh well that will be a different post.

Again thank you.

 

[Parthery]

Are you on 6P or 3P / 6C? Should be 6P for that motor.

 

[Curmudgeon]

and the analyzer said 680 rpm at idle which is fine while the boat tach was at 1400 rpm

:hmm And you don't find anything strange about an almost 100% difference? Just coincidental?

 

[seasick]

It just occurred to me. Is there an option for 2 stroke vs 4 stroke?

 

[DestinII]

I will verify that it is set for 6 P tomorrow, been getting home late to see under the console. Do not think this tack has a setting for 2 or 4 stroke.
And yes, I do find it strange that it is 2x and that is why I asked.
Thanks all, I will let you know what I find.

 

[DestinII]

Well I checked and it is set for 6P. There are definitely no options for 4 stroke versus 2 stroke but, there is a "4cyl-2P" position. The pamphlet that came with it says for this engine it should be set at 6P but
What would happen if I try the other option for a 4Cyl.
Can I screw anything up? other than the already screwed up tach.
What do you think?

Thank you

 

[Parthery]

At this point you know what your idle speed is....I'd put the boat in the water and while you are tied up at the dock with the motor idling turn the screw. One of the settings will get the idle RPM as displayed down to the correct number.

 

[seasick]

Well I checked and it is set for 6P. There are definitely no options for 4 stroke versus 2 stroke but, there is a "4cyl-2P" position. The pamphlet that came with it says for this engine it should be set at 6P but
What would happen if I try the other option for a 4Cyl.
Can I screw anything up? other than the already screwed up tach.
What do you think?

Thank you

Without the docs for the tach, I can't say for sure but trying different switch settings can't hurt. I highly doubt that the factory adjustment would be off by 2x .Most of the OEM tachs I am aware of have an option for 2 vs 4 cycle.
Have you tried contacting the manufacturer?