How do I set engine RPM

[bizzo15 52]

Hey guys,

 

my 312-8 with the Kohler Command doesn't seem to be in it's "sweet spot" when at full throttle.  How can I confirm this? Is there a way to check the RPM's?  If in fact it is running slower than what it should be what's the procedure to adjust the RPM.  Thanks a bunch guys.

[305 380]

you can check your RPM's  with a hand held tachometer ,  like the one Stewart Warner sells.  anyone who messes with small engines should have one.  they are a bit over $100 new , but can be found used on Ebay for a lot less

 

[Save Old Iron 1,563]

these work well and offer a user settable maintenance alert after so many hours

 

http://www.ebay.com/itm/331086473062?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Edited June 3, 2014 by Save Old Iron

[Save Old Iron 1,563]

a laser version that reads off the flywheel screen or PTO is also available

 

http://www.ebay.com/itm/New-Digital-Laser-Photo-Tachometer-Non-Contact-RPM-Tach-High-Resolution-DZ88-/131162619130?pt=LH_DefaultDomain_0&hash=item1e89e6bcfa

[Jim_M 178]

You set the rpms by moving the throttle stop on the side of the block.

[doc724 924]

What Jim M said must be correct.  I had the same problem with my 314 with the Command engine.  I could tell the RPMs were low because the M14 in another tractor sounded different.  However, I could not find the adjustment and the Kohler service manual was not helpful.   Maybe I did not look hard enough!  Anyway, I had to pay someone (groan) to adjust the RPM's.  It now runs the way it should. 

[bizzo15 52]

Thanks for the responses, my mechanical ability is fairly decent as i've worked on auto's and 2 stroke snowmobiles, but other than general maintenance and carb cleaning I don't know jack about small engines.  Where would I hook up this RPM gauge.  I see the laser one runs off flywheel but where would a normal one tap into?

[Save Old Iron 1,563]

if you are referring to the maintenance meter, the wire attached to the meter is wrapped 3 or 4 times around the spark plug wire.

 

The wire picks up the spark energy and the meter counts the spark plug "firings" to indicate engine speed and also tallies how long the engine runs.

 

 copy of the user manual can be found here

 

http://www.avtechtrading.info/uploads/AUTHOU03%20Tacho%20&%20Hour%20Meter.pdf

[Road-Track 39]

I ordered two of these digital Tach/Hour Meters last week, Thanks for the back up recommendation SOI!

[pacer 3,160]

The laser type is dead simple - and cheap ($30+-) it comes with a roll of reflective tape and you snip off about a half inch and stick it to any rotating part - flywheel, PTO, etc - and pull the trigger, aim it at the rotating part where the tape is .... and voila!

[Save Old Iron 1,563]

and if you have a  multimeter which measures frequency 

 

                                                                                                                                                                                                                                                              

[bizzo15 52]

The laser type is dead simple - and cheap ($30+-) it comes with a roll of reflective tape and you snip off about a half inch and stick it to any rotating part - flywheel, PTO, etc - and pull the trigger, aim it at the rotating part where the tape is .... and voila!

Wow that does sound dead simple may have to give it a whirl.  Only question is how accurate is it?  Probably enough for my purposes of setting engine speed.

[pacer 3,160]

I have checked mine against several elec motors - 1800 & 3600 rpm- and it is very accurate. I generally ck every engine I work on to see if any adj are needed. As you said it will surely get close enough to use on these engines.

 

I was just looking on ebay and found the price has come down even more, saw one for $14 with free ship!!  Search 'digital laser tachometer'

[bizzo15 52]

I have checked mine against several elec motors - 1800 & 3600 rpm- and it is very accurate. I generally ck every engine I work on to see if any adj are needed. As you said it will surely get close enough to use on these engines.

 

I was just looking on ebay and found the price has come down even more, saw one for $14 with free ship!!  Search 'digital laser tachometer'

 Just bought one on Amazon that had good reviews for $20 shipped.

[can whlvr 991]

heres the relector style rpm gauge,works great and very handy when you have several egines to set

[smoreau 658]

How to Set the Governor Adjustment - Top of page

If your engine revs with no closing of the throttle shaft, or surges, then the governor is probably out of adjustment. To set the governor on a Kohler (or virtually any engine)...

1. Install all the throttle linkages, governor parts, etc., in their respective places.
2. Loosen the bolt that clamps the lever to the governor cross-shaft that protrudes out of the engine block.
3. With the throttle plate blocked in the wide open position, rotate the cross-shaft counterclockwise until it stops. Now tighten the bolt.
4. That's all that's to it! But if this doesn't fix the problem, then perhaps a governor part inside the engine is damaged or the screws came out of the throttle plate, where it fastens to the throttle shaft.
5. And it doesn't matter how long or short the link is because the governor is adjusted by the clamp on the cross shaft. Actually, I don't know why Kohler made the link adjustable. It serves no purpose to lengthen or shorten it.
6. You can also go here for further details and pictures: http://cubfaq.com/govadjust.html.

And to set the high rpm governored speed, place one end of the governor spring in the middle to lower hole in the "L" shaped governor lever, and place the other end of the spring in either the top or second hole from the top in the short lever that's located under the carburetor or on the flywheel shroud. It's best to use a [Dixson] small engine tachometer to determine the exact rpm to prevent over-revving of the engine, which could cause the connecting rod to break. (Double the reading on the [Dixson] tachometer on engines with camshaft-operated ignition points.) The high speed governor limit for a stock engine is set at 3,600 rpm. For a stock pulling engine, set it at 4,000 rpm, or whatever sanctioning rules require.

Do not mistakenly rotate the cross shaft clockwise (opposite rotation than what it shows in the drawing above) until it stops, tighten the clamp and then run the engine! Doing this could cause the lever (see below) to jam into the governor flyweights, breaking off the lever and/or possibly destroying the governor gear assembly.

If the governor cross-shaft (the shaft that protrudes from the block) gets bent due to rough handling of the engine, and if it's not bent too bad, just use a hammer to straighten it. It's made of mild steel. But if it's bent severely and breaks off, it must be replaced. If this happens, usually the bushing/nut (Kohler part # 235476) will break and it will need to be replaced, too. Or, if the above adjustment was attempted, and the governor shaft keeps rotating without stopping, this means the flat lever on the shaft has broken off. This will allow an engine to operate dangerously at wide open throttle at all times.

To fix either of the above, another governor shaft (Kohler part # A23525601S) must be installed. To install another shaft, the entire engine must be completely disassembled. This means EVERYTHING inside the engine block (crankcase) will need to be removed. And then the replacement shaft can installed from inside the crankcase. But before the old shaft is removed, the bronze bushing/nut on the outside must first be removed. The governor gear assembly doesn't have to be removed. The shaft lifts out from inside the crankcase and is installed in reverse order of removal. And it'll be a good idea to place a small bead of weld on the flat lever to secure it to the shaft to prevent future breakage. (I think this is something that Kohler should have done.) I realize that this is a lot of work just to replace a small [important] part, but it must be done in this way. There is no other way to replace it.

[bizzo15 52]

So i received my point and shoot laser tachometer  the other day and decided to give it a try tonight on the horse.  I put some of the reflective tape on the pto and fired the old girl up.  Full throttle and it's only reading 2900-3000 rpms.  From what I've read these engines should be at 3500-3600rpm.  Is the PTO an accurate place to measure engine RPM, I don't want to adjust the RPM's and do harm to the engine because my readings are inaccurate.  Thanks!

[smoreau 658]

Yes that should be fine. The larger the diameter, the more accurate it would be, but that would be at more RPM's then that engine would ever handle. Just fallow my above post to set the governor and it will be very close.

Edited June 11, 2014 by smoreau

[bizzo15 52]

Perfect, I will follow that procedure and report back tomorrow or the next day, thanks for the help!!

[WH nut 553]

So i received my point and shoot laser tachometer  the other day and decided to give it a try tonight on the horse.  I put some of the reflective tape on the pto and fired the old girl up.  Full throttle and it's only reading 2900-3000 rpms.  From what I've read these engines should be at 3500-3600rpm.  Is the PTO an accurate place to measure engine RPM, I don't want to adjust the RPM's and do harm to the engine because my readings are inaccurate.  Thanks!

3600 is where Kohlers are designed to run

[Fordiesel69 232]

these work well and offer a user settable maintenance alert after so many hours

 

http://www.ebay.com/itm/331086473062?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

 

How accurate are these?  I wrapped 4 turns of wire arournd the plug wire like it sais, and the rpms jump from 3100 to 4050 the whole time.  I have the meter set correctly. 

[bizzo15 52]

So I attempted to do the governor adjustment tonight and I couldn't get the governor cross shaft to turn at all counter clockwise with a pair of needle nose visegrips on it. I didn't want to muscle it because it looks like that tiny little shaft is super easy to snap. What. Do I do now?

[Save Old Iron 1,563]

How accurate are these?  I wrapped 4 turns of wire arournd the plug wire like it sais, and the rpms jump from 3100 to 4050 the whole time.  I have the meter set correctly. 

The electronics are accurate, the "antenna" used to pick up the spark signal is much like adjusting an AM radio for best reception.

 

The number of wraps and the DIRECTION of the wrapping needs to be rechecked. I installed one of these just a week or so back on a twin Kolher and ended up with 5 wraps to get stable readings within 20 RPM's. Your system may require less than 4 wraps or more than 5 wraps to get a strong and repeatable spark signal. Too little wraps and you have a weak signal that triggers intermittently. Too many wraps and you swamp the electronics in the tach causing double triggering and electronic "confusion".

 

The instructions for my tach also stated to wrap the pickup wire starting with the Tach side of the wire toward the plug, wrapping the end of the wire AWAY FROM to the plug. I'll see if I can find the picture of the wrap sequence and post it here.

 

<edit> and the Tiny Tach instuctions show the exact opposite - go figure.

Edited June 13, 2014 by Save Old Iron

[Save Old Iron 1,563]

this is not from my manufactuer but ir clearly explains the orientation of the pickup wire

 

http://tinytach.com/pdf/Tiny-2A-Instructions-2013.pdf

[Save Old Iron 1,563]

and yet another manufactuer with an opposite view on how to orient the wire pickup.

 

this is the tach I am using successfully.

 

 

http://andytach.com/shop2/tachometer_andytach.pdf