Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Hi all,

I need to adjust the RPM of my Tecumseh L-Head (9 HP / 318 cc) engine that I bought in 2007.

For that purpose, I plan to purchase "digital photo (laser) tachometer".

From my understanding this tool works by sticking a piece of reflective tape on a rotating part of the engine (such at the shaft near the pulley where the belts are located). The tool then counts the number of time this piece of tape passes in front of the laser beam in one second and multiplies by 60 to display the RPM.

Did anyone ever used such a tachometer? If yes how are you satisfied with this tool?

Also, I need to know the RPM values that this engine should be adjusted to at: full throttle and also when idling. Do anyone know these RPM values.

  It might be that what I read was about a newer model.  It mentions the coax. 

Strange language "transmits" versus carries.  There is no transmitting going on. 

I doubt the "winds around" refers to coax but since coax is used and so few wires involved coax is probably in there.  Probably most of the length of the pickup wire is coax and then some flexable wires going to the center wire and a grounding clip on the coax jacket.  ?? No pictures no explination. 

So your's has two wires running directly into the unit and not able to connect and disconnect.  I guess if something breaks it's ok as long as it's not too close to the device body. 

New Standard TT2A - TINY TACH™
RPM reading adjustable from 1 spark per 2 revolutions to 8 sparks per revolution. One TINY-TACH™ now works for most gas engines.
RPM display from 1 to 19,000.
RPM update time 1/2 second.
Hour meter records total actual running time on your engine.
Job timer can be reset to record run time for record keeping.
Coax cable transmits signal without EMF interference.
1 Antenna cable winds around your spark plug wire to give you the RPM reading – clean and simple to attach. Signal strength can be controlled by the antenna wire.
Standard cable length is 6 feet. Additional length can be added at the factory for $10. If not standard, please specify total length needed in the "comments" section at the end of the order page.
TINY-TACH™ unit is potted to prevent damage from moisture and vibration. Lithium battery life 5+ years, not replaceable.

I think you mentioned having one at a camp which I assume is unheated.  So they take cold ok at least -30F?

I found one in China, no bat, cheap - $18 includes shipping, tach and hour.  Probalby clones of.....

Never had a problem with cold temps.  I had the Readi-alert on my snow blower for a while.  It always worked regardless of temp.

$18.00 is  good price.   You can buy 2.5 of those for the price of the one I bought. 

In using the laser tach, there must be an unobstructed view of

the piece of tape. If the tach gets interupted in "seeing" the tape,

the readings will be inaccurate. BTDT

T.J.

Can any reflective tape be used?  There's fake chrome tape.  Will that work?  I'm thinking of using it to meter rakes and impellers.  Not sure if tape on am impeller would reflect back in the right way.  I think you would have to have the tape on a surface square to the meter.  That might be tough to do on an impeller.  For a rake it would be easy.

The laser ones usually come with some tape.  I have heard of people cutting the tape into strips, but not peeling the backing off then using scotch clear tape so they can reuse them instead of buying more tape.

trouts2 wrote:
I have read that people using  the shinny duct tape works perfect. I believe any shiny material will work.

To check the impeller rpm with a laser tach.  I'm guessing you would probably have to take the reading looking down the chute, or take the chute off.  Either that or I think you could get an unobstructed view shooting in right above the auger gear case.

Amazon has a number of them for sale. With reviews

   I just ordered a $15 lazer tach and an $18 small inductive tach.  I doubt it will come with tape.  I have a roll of very shiny silver back tape which I hope works.  Bottom fishing and hoping for the best. 

  A small pack of tape costs $41. 

I installed a TinyTach to adjust RPM and accumulate hours. The inductive connection couldn't have been easier. One thing I didn't expect was the RPM drop under just light loads. Full throttle no load is 3700 RPM. Under a little load it drops to 3500-3550. Under really heavy load it's down to 3000. It seems as though it dials in more throttle the farther it gets away from it's unloaded RPM. But even though it's down to 3500, it should have plenty of power to pick back up to 3600. It doesn't sound like it's at full throttle even when it's running at 3500 rpm and minimal load. Thoughts?