Small Engine RPM?

[cwarrix]

Hi, I was wondering if anybody could tell me an easy way to figure out what the 1/2, 3/4, and full throttle RPM's would be for this engine? It is off of an old Craftsman lawn tractor which is now being used as a power unit for a log splitter. I have no idea what the RPM range is, but would like to know so I can guess the pump output, and so I don't run the pump too fast.

I'll attach a picture, but it is hard to read, it says 18HP B&S, twin cylinder, electronic ignition, cast iron bore.

 

[cwarrix]

Another picture of the whole unit...

 

[SkyPup]

You need to attach a small tachometer to monitor the engine rpms.

I put one on our logsplitter too to save gas and monitor the hours of operation for oi change outs.

 

[JerryG]

The model number of that Sears tractor is 917.255919

 

[cwarrix]

Thanks SkyPup, do you remember where you got it?

 

[SkyPup]

I got them from Northern Tool

<a href="http://
northerntool.com" target="_blank">
northerntool.com</a>

Just search for tachometer and you will see it.

It is a digital hour meter and tachometer. All you do is wrap the lead around the spark plug cable, super simple. /forums/images/graemlins/wink.gif

 

[cwarrix]

Thanks for the info SkyPup, here is a link to the two that I found at Northern.

Tach 1

Tach 2

 

[cwarrix]

Thanks for the model number JerryG, might come in handy if I need parts.

 

[SkyPup]

The one we purchased is the first one.

 

[1962]

you can go to just about any local lawn & garden, or mower repair shop and get one over the counter for about the same price. mine is made by SEN DEC. look on thier web site for more info. i have 7 of these on various toys and they are great. show hours,engine speed, and some models have a user programable oil change reminder./forums/images/graemlins/smirk.gif

 

[GreenQuality]

Looks to be 180deg opposed twin cylinder from briggs i/c

 

[Boog]

I have a B&S 18 HP v-twin (1999) and I have one of those SenDEC small tachometers on it. WFO is around 3000rpm. I find that 24-2500 is what I like to mow at. The tach was very helpful in setting the idle which I knew was way to high before - I now have it set at around 1100rpm.

 

[cwarrix]

Thanks for the info all, I will most likely try to find a tach this weekend someplace locally. If I can't find one locally, I'll order online. I'm not in a big hurry as I have all of my wood split for this year. I just wanted to do some work on the log splitter as a Winter project. Since it is home made and I don't know a lot about it, I thought it would be good to know the RPM range of the engine, pump output, etc. so I can run it at the best speed and not cause any damage ny running too fast.

I ordered a new 10 gal hydraulic reservoir since the one that is on it is only about 2gal max. not big enough. Still trying to find the pump GPM and pressure ratings. Plan to add a pressure gauge and a filter as well. I'll probably have about $500 and a little time in it when I'm done.

 

[ZackaryMac]

One thing to remember about air-cooled engines, especially stationary ones, is that they are designed to run at their designed rpm, not only for max HP, but to cool properly.
If the engine is a 10HP and that is at 3600rpm for example (common rpm for singles), it should be run at that speed so the fan on the flywheel can blow enough air across the head/cylinder to cool it properly. Heavy work at lower RPM, such as mowing heavy grass, will cause the motor to run hot.
Also, they don't idle down low like a car. They idle high to keep cool, and splash lube models need to splash enough to lube properly. Many of these engines are quite simple, and are designed to operate in a short operating rpm range.

Not trying to be smart, just something to think about.

 

[cwarrix]

</font><font color="blue" class="small">( One thing to remember about air-cooled engines, especially stationary ones, is that they are designed to run at their designed rpm, not only for max HP, but to cool properly.
)</font>

Hi ZackaryMac, I had actually wondered about that. I had an old riding mower that would actually shut down when it got hot. I think the heat caused the coil/magneto to break down. Once it cooled down it was ok again. I started looking at the engine and found some mice had made a home between the metal covers that cover the engine. Once I cleaned all that junk out, it worked much better

Any ideas on how to keep this engine cool. Should I remove the tractor hood, since I really don't need it, except to keep the weather off the engine. How about adding an electric cooling fan?

Thanks!

 

[cwarrix]

Got my Tiny Tach today. Looks like a well built unit, just what the doctor ordered for this application. Thanks for all of the input on this!

 

[1962]

looks good now your set. /forums/images/graemlins/smile.gif the battery is those last a real long time. the one on my outboard motor for the fishing boat is 11 years old and still going.

 

[OSA]

I think the name of the unit is Digitech or Digitron???
It is a small electric gauge used in racing go karts. The RPM sensor is zip-tied the spark plug wire. The heat sensor is a ring that is sandwitched between the head and the spark plug. You should be able to pickup a used unit at a good kart shop or Ebay.

Dan

 

[cwarrix]

Thanks for the info OSA, I found one online the other day and ordered it. This one is called Tiny Tach, looks like it will do the trick.