Homebrew revcounter for tohatsu 18 2 stroke ?

[ruddles]

Hello guys
Anyone made a lashup / homebrew rev counter for a tohatsu 18 ?.
I dont want it fixed, just for testing occasionaly. Is there a simple design you have seen using cheap parts ?
Cheers
Ruds

[doggypaddle]

just use a cheap DMM which has a frequency function. connect it to one of the alternator coils and ground. the alternator output frequency is directly proportional to engine rpm,
and the number of cycles per rev is the number of poles the alternator has. or alternatively connect to the primary in the coil pack and use that frequency the dmm will register 1 cycle for every firing stroke on that coil.
ie on a 2 stroke 50HZ = 3000rpm.
never tried it on an outboard but it works for everything else.

[9D280]

Alternatively any boat jumble / ouboard dealer will probably have an old Tacho for a few quid. Most have a selector on the back to choose the number of poles on the alternator.

Connection pretty much as described above.

[ruddles]

Great replies, seems logical !.
WIll try the DVM with freq approach..

Cheers n much beers

Ruds.

[Andy JC]

Or you could try one of these: http://www.tinytachuk.com/

I went for the comercial version which can be used on any engine type, 2 or 4 stroke, 1 to 8 cylinders. It costs £45 inc del.vat - £10 more than the standard version.

Ordered one myself last week and the guy sent one out with an invoice. You can then send him a cheque as payment. I've attached mine using cable ties, has it's own power supply so only took 5 mins and easily removeable - Seems to work well

*I have no connection with the company, just impressed with the service*

[ian parkes]

Originally Posted by Andy JC

Or you could try one of these: http://www.tinytachuk.com/

I went for the comercial version which can be used on any engine type, 2 or 4 stroke, 1 to 8 cylinders. It costs £45 inc del.vat - £10 more than the standard version.

Ordered one myself last week and the guy sent one out with an invoice. You can then send him a cheque as payment. I've attached mine using cable ties, has it's own power supply so only took 5 mins and easily removeable - Seems to work well

*I have no connection with the company, just impressed with the service*

me too tie wraps and all , great little bit of kit , and glad i had it for running in a new motor and counting the hours

[Andy JC]

will also come in handy when making engine/gearing mods to my DRZ400 thumper (single cyl, 4stk) which also has no rev counter