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.

Hi there.  The MTC department of my plant uses them to verify screw speeds on our extruders.  They work fairly well.  I haven't heard too many complaints and their readings usually agree with the encoders.

Just wondering why you wouldn't use an electronic digital tachometer.  They're around $25.00 to $50.00 and are very simple to use.  It usually has just one wire that you wrap around the spark plug wire.  That's it. 

 http://redingtoncounters.thomasnet.com/item/all-categories/del-51-electronic-lcd-hour-meter-maintenance-meter/5140-0311?&plpver=10&assetid=g2

Max rpm is 3600.  Min rpm will be between 1500 to 1700 depending on how well your engine likes to idle.  I have an ohv B&S engine.  The lowest I can get it to idle is 1650 rpm but that might be due to the throttle setting from the factory.. 

Hi Borat,

The laser tachometer is also not expensive (http://www.amazon.com/Digital-Laser-Photo-Tachometer-Non-Contact/dp/B000EUT9ZS).

This tachometer can be used on any rotating machine, as long as you have access to a rotating part where you can stick the reflective tape.

It works with gas engine, diesel, and with electric motors.

briggs and stratton makes a tach that has a thin wire that slides out of a base plate and disc .you place it firmly by hand and hold it in place why you slowly rotate the disc which advances the wire out of it. the wire oscilates back and forth and when it reaches it's widest vibration position it has an index between the plate and disc that tells you the rpm's.you can use it on anything you can place it on that has a rotating shaft.they use them for blower speed indexing on furnaces also. it is suprisingly accurate.

A pocket size RPM meter that is compact, competent and inexpensive. It will tell you the RPM of any piece of revolving machinery by transforming vibrations into revolutions per minute on a gauge that is simplicity itself.

NEW Genuine Tachometer This is a NEW in the box Briggs & Stratton tachometer. Works on most types of engines such as Tecumseh, Kohler and many others. Range: 800 - 50,000 RPM 14 - 750 Cycles Directions Included. 19200 Works on most types of engines such as Tecumseh, Kohler and many others. Range: 800 - 50,000 RPM 14 - 750 Cycles Directions Included. 19200 Works on most types of engines such as Tecumseh, Kohler and many others. Range: 800 - 50,000 RPM 14 - 750 Cycles Directions Included. 19200

I have one of those wire type tachs.  Mine's made by a German outfit Treysit.  I have a diesel power plant at my camp and I'm totally impressed with the way that thing works.  I set my power plant at 1800 rpm by that thing.  I think I'll get one of those hand held laser units though.  Being a power plant, a steady 1800 rpm is essential.  I know the Treysit unit shows 1800 rpm but reading the scale it could be off by 100 rpm or so and I wouldn't know it.  The laser unit will give me a definitive reading.    

Borat:

    The 51 tach looks good and does not require a battery if I have that right.  It picks up energy to run from spark.  I'm looking a tach to put on various machines to check stability and RPM sag under various loads.  That would require a lot of install and removal and tax the sensor wire.  Do you think it would stand up to that?  Have you seen any better since you bought yours for the same ballpark price?  

   The Tiny-Tach looks ok and the bat go for several years so probably ok also.  Not sure about that pickup either.  If anyone has one please post what you think about the robustness of the pickup.

   If anyone has a suggestion of something better or more functional please post.

I picked up one of these a couple months ago.  It seems decent, but I have not used it much.

http://www.amazon.com/gp/product/B002Z32OHW/

trouts2 wrote:
Trouts:

Is this what you're looking at? 

http://www.contractorstools.com/redington.html

I have one of these (Readington model 5140-0311) as well as a Tiny Tach.  Both devices are quite ruggedly built.  The Readington unit reads higher rpms than  the Tiny tach does and it also has a slot in the back of the unit where the impulse wire is placed while taking a reading.  That make is easier to move around.  For my purposes, I just put a piece of suitably sized wire on each machine I want to monitor and just move the tach from machine to machine without having to take the wire off of the spark plug lead.  Another nice feature of the  Readington tach that I have is that it reads up to 20000 vs 9999 of the Mini Tach.   I don't like the idea of batteries either.  If you can get one that's powered by electrical impulse, that's the way I'd go. 

Yes, 5140-0311, Inductive Model- Surface Mount, Inductive, Hours with 1:1Tach

I looked at that tach because of your reply in post #2. 

The Tiny-Tach goes to 1,9999 and the 0311 to 7000.

Both have batteries in potted cases so not replaceable. 

The 0311 is 15 year, the Tiny 5 year but prior posting on Abbys say the Tiny's battery lasts much longer.  I'll snoop around for one without a bat.

The 0311 literature on hookup wire they call "Lead wire" only shows one end.  That looks like a plain wire which wrappes around the plugwire a few times and has an allegator clip end to clip onto back onto the lead wire.  The other end is not shown.  Can any wire be used?  What is required on the other end?  Do you have to have something connected to the wire or do you just connect bare wire to something?  Is there a hole you stick the wire into?

The Tiny talks about coax wire for the pickup.  Maybe they have a length of coax and a short wire for a setup like the above soldered to the end of the coax.  What about the other end of the coax?  How is it connected to the device?

Can both use a plain wire on both ends?   I have coax I can strip if there is no elaborat connectors requires on the ends.

The model 51 uses any wire that can be squeezed into the slot on the back. 

The Tiny tach that I have uses two normal pieces of wire that are permanent parts of the instrument.  One wire goes to the spark plug lead and the second wire is a ground.  I prefer the single wire unit.

Can't tell you any more because these are the only two units I own.  I don't know anything about units that use coax.   For me, my preferences would be:  a) no battery, b) single wire), c) removable wire.