Kohler engine idle speed 27hp

Troy · January 17, 2006, 07:20:30 PM

My Kohler 27hp woudn't idle at the recomended 1200 (+/- 75) rpm and would always backfire when I reducing speed from full throttle down to idle speed. Engine would run fine otherwise. When I adjust the idle up to where it runs steady and not cause the backfire issue, the tach reads 1450-1500. During the course of operation the idle speed seems to fluctuate sometimes too, 1500 for a while then an hour later it is down to 1300. What do you have yours set at?

jpgreen · January 17, 2006, 07:59:20 PM

Sounds like maybe the timing slipped out Troy.

I knew there had to be somethin' wrong with a Peterson!!

-cept that's the Kohler part.. :D :D :D

Troy · January 17, 2006, 08:12:47 PM

It runs fine, just has a touchy idle. No matter how awsome that WM is once you are finished rebuilding it Pat - you know you will still yearn for a Peterson.

jpgreen · January 17, 2006, 08:19:07 PM

:'( ................ ;D

VA-Sawyer · January 17, 2006, 09:35:26 PM

Do you believe it ? Those two are on opposite sides of the country, and going at it like two little boys stuck in a small room all day !

GlennG · January 17, 2006, 09:48:56 PM

Troy

Check to see if your intake manifold bolts or carburator bolts are loose. Sounds like you might have an air leak. I doubt it slipped cam timing as the cam is gear driven unlike automobiles which are belt or chain driven. From what you describe it seems like a minor problem that should be easily fixed.

Glenn

GlennG · January 17, 2006, 09:50:50 PM

Troy

Also is it a bit harder to start and do you have to keep it on choke a a little longer than normal? These would be air leak symptoms.

Glenn

GlennG · January 17, 2006, 09:54:34 PM

Also Kohler engines have very tight engine tolerences. If the oil is not fresh and of high quality they are prone to sticky valves. Quality oil and a couple ounces of Marvel Mystery oil help these motors a lot.

Glenn

Troy · January 17, 2006, 10:05:22 PM

Thanks for the response Glenn. I was wondering how long Pat and I would have to rib each other until someone jumped in with some thoughts on engine idle speed. It seems to like the choke on when starting cold, but you have to back it off as soon as it starts or it will overload and stall out. Restarting after it has been running requires just half throttle.

logwalker · January 17, 2006, 10:12:55 PM

It has got to be a lean situation. Is it an older engine or newer. Coud be the float level or a plugged pilot jet. Did it sit for a long time with gas in the carb? Today's gas has a real short shelf life and varnishes the jets when it goes. Easy fix. But the previous post about air leaks is very possible too. But it is a lean air/fuel ratio. Keep us posted. LW

scsmith42 · January 17, 2006, 10:40:09 PM

I concur with Glen and Logwalker - your problem is a lean condition caused by a leak between the carb and the head.

The easy way to find the source of the leak is to idle the engine, and take a can of WD40 or spray carburator cleaner with the extended hose and slowly spray around all of the gaskets on the carb and intake manifold. The engine will speed up when you spray wherever it's leaking.

Should be a simple fix. Good luck.

Scott

Captain · January 17, 2006, 10:42:06 PM

Troy, see how it runs in warmer OR colder weather. May just be a touch of carb icing...how humid and what temperature is it??

Cracking the throttle to 1400 will relieve that symptom. All should be normal above about 48 degrees outside temperature.

Also, if your clutch brake is stuck and the blade does not stop at idle, the engine will idle rough. The blade should coast down to a stop when the engine is below 1200 rpm.

Captain

Troy · January 17, 2006, 10:52:52 PM

I'll run the suggested test for air leak next time I have her fired up. It is a new engine and old fuel should not be a problem. I have run it on warm and cold days, but did not note the performace as per the temp and humidity. I'll pay attention to that next time as well. I do recall the idle speed slowing down as the air cooled down in the evening last time I was milling. Captain - at what temp and rh can icing occur?

Captain · January 17, 2006, 10:59:37 PM

Icing is worst below 45 degrees F, down to where the air dries out below freezing. Especially with moisture in the air. (high humidity)

The Kohlers will ice slightly from time to time, but not nearly as bad as my Honda V twin does. Now saying that, I've never had a problem with the 13hp Honda on the log trailer.

Captain

Troy · January 17, 2006, 11:09:00 PM

Well I have run that engine well below 45 ambient temp. Last time I cut it was 27 degrees when I got started and the mill had been setup overnight outside just covered with a heavy tarp. That would explain the gradual change of idle speed as the outside temps would rise and fall throughout the day. Once I find that air leak and get her tightened up it should be easier to track.

Pat - you getting all this??

jpgreen · January 17, 2006, 11:20:27 PM

There's no hope.. :'(

Send it west Troy, and I'll help you recover some of your losses. :-[ :'( :'( The pain, The PAIN!!... ;D :D

jpgreen · January 17, 2006, 11:33:27 PM

Quote from: Troy on January 17, 2006, 11:09:00 PM
Pat - you getting all this??

.....................................................

logwalker · January 18, 2006, 02:48:47 AM

now that you say it is new that changes things. It is possible it is just the pilot jet adjustment. If you have one that is. With the new regs you may have a restricter on the jet to keep you from adjusting enough. They usually pop off and you are good to go. LW

sawwood · January 19, 2006, 10:19:45 PM

Troy the same thing happen with JR Norwood Mill, It has a Honda and
what i found was the air filer was full of saw dust, clean it up and the
problem was fixed. Some time the little things are what gives us the
most trouble if we let them git to us.

Sawwood

ladylake · January 20, 2006, 06:22:27 AM

Troy
Is it backfiring out the muffler or through the carb? Muffler = too much gas, carb iceing, dirty filter, or leaky needle valve. Through the carb = not enough gas, clogged idle circut, gas filter and line must be OK as it runs good at speed. Steve

Troy · January 20, 2006, 08:44:29 AM

Steve,

I backfires through the muffler, but only if the idle speed is set low. If I drop the throttle down from full rpm to idle and the idle setting is below 1300 rmps it will backfire as it hits the low end. If I have it set around 1450-1500 rpm or just lower the throttle lever to this rpm range manually it will not.

Troy

RichlandSawyer · January 20, 2006, 01:59:24 PM

Troy;

I have had the exact same problem on a 22.5 hp kohler. The first time it happened i struggled for weeks trying to figure it out finally gave up and took it to the small engine guy he said he knew what it was, He puled the carb off and hosed the day lights out of it with carb cleaner and let it run on to a clean towel. After a bit a tiny piece of something showed up on the towel. Put it back together and she ran fine.
He told me that you usually find something in the tube that goes from the bowl up through the carb. The next time it started acting up i tore it down and flushed that tube, i didnt se the crud but it fired up and ran fine.

Mine would run ok underload but with no load and throttled up it would surge and when i throttle down it would back fire (scared the poor pups to death). I bet if you ran it with nothing attached the motor it would surge at high RPM.

Just my experience, hope you get it running smooth.

RichlandSawyer

Troy · January 20, 2006, 02:07:13 PM

RichlandSawyer - That sounds exactly like mine. I'll pull that tube off and flush it tonight. Thanks for the info. I'll let you know what the results are. I'm off to start milling the big white oak tomorrow...