tach on a '94 2 stroke 15 hp

[baja power]

When it comes to O/B's, i'm not the guy to go to (big power, high displacement I/O are another story...) However I just picked up a RIB to use as a tender for the larger boat. Love it to death. The 15hp Johnson 2 stroke pushes it right along. Although there is no instrumentation, i wish to put a tach on it so i know what i’m turning in order to do some prop testing and get this thing dialed in. My question is can you put a tach on this motor? And if so how would you go about it? Would i need a special tach since its 2 stroke or only 2 cyl?

 

[jtexas]

Re: tach on a '94 2 stroke 15 hp

check out http://www.tinytach.com

 

[baja power]

Re: tach on a '94 2 stroke 15 hp

i was really holding out for an analog gauge..:/ but its good to know that is a second option.

 

[jtexas]

Re: tach on a '94 2 stroke 15 hp

understood...in that case you'll need to know whether it has an alternator and/or rectifier...if it's electric start it almost certainly does in which case just about any marine tach would work.

if unsure, post the model number we can look it up.

 

[baja power]

Re: tach on a '94 2 stroke 15 hp

MOD NO.: J15RETB


Its a pull start so im sure theres no alternator or the like. I just dont like the idea of the tiny tach updating every 2.5 seconds.. seems awfully slow to me.. id perfer raw real time data.

 

[jtexas]

Re: tach on a '94 2 stroke 15 hp

1993 model, no tach sender wire. Would work with the stator & rectifier from the electric start model but that's a lot of trouble.

Alternative is an inductive tach.

That 2.5 sec delay is what's kept me from getting tinytach, too. The commercial version is 2x per second but 2x the price.

Surprised nobody else has jumped in on this yet...if you post the question in the "Electrics, Electronics and Trolling Motors" forum it'll get more exposure, not everybody reads the Johnnyrude repair forum.

 

[byacey]

Re: tach on a '94 2 stroke 15 hp

If you know someone with some electronics experience, Do a search on this forum for:
Tachometer black box for magnetos, Attn byacey, lark2004 (DONE?!?) Posted: 6:10pm 6 Sept '05

 

[Snowdrggn]

Re: tach on a '94 2 stroke 15 hp

Just a note,
The commercial Tiny Tach requires an external, constant voltage source. The oiginal one does not (built in battery).

I have a Tiny Tach mounted on my 15hp Evinrude, although the update is a bit slow, it is more than usable for setup prop testing, and keeping control of WOT rpm when running a pitched down prop. I run a small inflatable and regularily tow a kneeboard with it.

Cheers,
Snow

 

[byacey]

Re: tach on a '94 2 stroke 15 hp

I have been using an analog tach all summer based on a modified version of the magneto black box mentioned above. It works well, and was easy to build.