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 Kohler Command 13 ohv governor question

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Kohler Command 13 ohv governor question Empty
PostSubject: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeTue Apr 30, 2013 12:51 am

I do not wish to start a huge debate, as I do know bypassing a governor can and eventually will damage your motor if you rev over +/- 3600 rpm consistently. Here's my question however and I do want as many opinions as possible (please?).

I am in the final stages of the build on my all terrain tractor (ok, Doug - rally mower Wink ) and I am considering when hooking up the throttle to the wheel ... bypassing the governor. I have read/heard that doing so on a Kohler is a horrid idea and that they can't take the abuse for long. But I've also read that the Kohler command can take a lot more overall abuse than either the Briggs OHV or the Tecumseh OHV or Flatties from either. So, assuming this is true why should I not bypass the governor?

I don't seek to run it @ 5000 rpm all day or anything like that... but given the obvious fact that it's full pressure lube it alleviates the dry cylinder conditions often found with the briggs and tecumseh when doing the same governor bypass. Can the rods/valves handle the extra RPM? What about the flywheel itself?


Opinions, facts, thoughts?
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Doc Sprocket
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PostSubject: Re: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeTue Apr 30, 2013 6:14 am

Since I'm new here, I will try and keep me response as neutral as possible. I do not want to get into a pissing match with anybody- whether they know more than me, or less...

A basic point first- any time you modify an engine away from stock, you potentially shorten it's life span. Be smart bout it, and you probably won't notice the difference.

Second- engines of this type are designed to run all day at 3600RPM. Keep feeding it fresh fuel and stay on top of the maintenance, and it'll go a loooooooong time, 24/7.

Third- the accepted industry standard is 3600RPM, and while that is generally the governor setpoint, your flywheel is NOT going to grenade if you exceed that speed. They are manufactured with a LARGE margin of error, and assuming it isn't damaged, will spin a hell of a lot faster with no worries.

Fourth- IF speed were to get totally out of hand, your connecting rod(s) is MUCH more likely to fail than your flywheel. I have seen many rod failures. I've never seen one flywheel go off. There's a TON of fear, BS, and myth on the 'net about that sort of thing. Let's see documented proof before we ride the rumour train.

Fifth- it is my own experience based preference that IF you're not going to use the governor, remove it- don't bypass it. This is a general statement. SOME governor flyweight assemblies are more sensitive to overspeeding than others- And if it were to let go, these are pieces you do not want flying around inside the crankcase.

The last point I would like to make regards your valve springs. When you reach a certain RPM- usually in the 5000-6000 range, your engine will experience valve flutter. Basically, the springs aren't strong enough to slam the valves closed fast enough for the cycle speed. This causes a compression loss, and your engine will refuse to accelerate beyond that point. It acts as a natural rev limiter. So- When removing (or bypassing) the governor on an otherwise stock engine, I always advise folks to keep the stock springs and do NOT upgrade to performance springs.

Unfortunately, I cannot give info specific to your particular engine. I work on a lot more Briggs, Tecumseh, Honda and clones than Kohlers.

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Last edited by Doc Sprocket on Wed May 01, 2013 5:53 am; edited 1 time in total
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PostSubject: Re: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeTue Apr 30, 2013 9:24 am

Agree with everything Doc said and will add that my group, which runs 5 tractors currently, always runs without the governor.

We do not hold them wide open all the time but we aren't overly concerned about "flooring it" depending on the situation. We have been doing this for about 15 years now and have had a couple engines wear out, but they put up with the abuse a lot better than is rumored.

Another thing that I have mentioned in other threads is that the governor is not primarily a rev limiter. It is a device to keep the engine at whatever the speed is requested by the throttle. Think in terms of mowing and hitting a particularly thick patch of grass, the engine pours it on to avoid stalling. Now take that thought and put it into offroading, you are climbing a hill and hit a bump or rut, the engine bogs a bit and the governor compensates by adding extra fuel. Now you are doing an unexpected and ill timed wheelie and flipping over backwards.

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PostSubject: Re: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeTue Apr 30, 2013 9:37 am

Ok, thanks you two... I'm still up in the air as to whether to remove it - but I found what seems to be the only video on youtube about the Kohler OHV singles and their governors. Please, keep the comments and suggestions coming!
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PostSubject: Re: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeWed May 01, 2013 5:49 am

Rainbow- I'm glad you brought up the bit about the governor being more than just a rev limiter- you're absolutely correct and most people don't seem to understand this.

In fact- if one were to have a good, close look at the throttle linkage on a governed engine, you'd see that there is no direct mechanical linkage between your throttle and the carb. All your hand (or foot) throttle does is is alter spring tension.

If anyone is interested- some time back I wrote a lengthy article on governor function, and the myths and facts that go along with the whole thing.

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PostSubject: Re: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeWed May 01, 2013 11:46 am

Rainbow is one of our gang.

Here is what I posted in another thread on governors.




MurrayMayhem wrote:



All you have to do is put a stopper next to that bar that moves the hook tht moves the btterfly on the carburetor.



If you adjust the carburetor to keep RPM's down, you will have no power under load.

Governors are there for a reason, and work well. When you set the throttle you are telling the engine to run at a certain rpm, regardless of load. So if you are in neutral, throttle is halfway on, it's about 1500 rpm. No load, governor only opens throttle a little bit, to make 1500 rpm's

If you put it in top gear and let out on clutch, the engine is going to be under a load. Governor will try to keep the RPM's at 1500, so it opens the throttle, anywhere from a little more, to all the way, to keep the RPMS up.

Problem is on a racing tractor, you let out on the clutch, and the governor will open the throttle all the way when it sees the load. This makes for some scary full power times, such as when you are trying to creep up a steep hill. It won't rev any faster, but it will put full power on if you bog it to 1000 rpms, until it reaches the 1500rpm you set it at.

No governor, gas is directly linked to throttle, is a demand power setup. You control how much power the engine is putting out. Much easier to feather your way out of a tuff spot.

If you are really worried about overrevving, you can get a RPM limiter, that cuts the spark if the engine exceeds a certain RPM.

And another post.

You can adjust the governor for higher RPM's, but it is still going to be RPM based, not power based.

Diesel governors can be power based, and just limit top rpm. Some are RPM based, such as for generators and tractors. All diesels have governors built in, and they are tuned for each application.

Lawn mower ones are all RPM governors.
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PostSubject: Re: Kohler Command 13 ohv governor question   Kohler Command 13 ohv governor question Icon_minitimeWed May 01, 2013 3:59 pm

IF I were to remove or otherwise adjust the governor, it'd be to gain a few extra hundred RPM under certain situations - that's all. An extra 400-500 rpm comes in handy once in a while. Last winter such a slight modification saved my life. My late 90's craftsman speed tractor was being tested (by me) and a car cut me off. I could have either slammed the throttle back and hit the car @ about 40, tried to out turn the car and likely roll the tractor thereby getting ran over... or goose the throttle a bit higher to get past the almost-wreck. I goosed it, and with those extra RPM available, it saved my arse.

When I posed those questions it was more regarding the durability of the kohler ohv under such a situation. I did something similar to a K series once (131S I believe it was) and it worked pretty well and only occasionally gave me any trouble from it - usually when due for an oil change.

I guess I'll just leave it be anyway, it's my last reliable motor until the two briggs ohv get finished.
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