Author Topic: Carb float adjustment on a Kohler Courage SV735  (Read 6354 times)

rccolacc

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Carb float adjustment on a Kohler Courage SV735
« on: August 07, 2013, 10:44:06 PM »
I saw a few of your videos on Youtube just now, so I'm here now on your site looking for tech help.

I just bought an '06 Craftsman YS4500 lawnmower the other day from a lady in town.  It had 200hrs on it, seemed to be in good condition, so I got it.  Anyway, after using it a few times on my yard, I'm noticing it's running rich.  It really has a gas smell when you lift the hood, and the engine has a miss through all RPM ranges.  It's really acting like it's got the choke partially on.  Anyway, I've done my fair share of small engine repair, so I decided to tear apart the carb and clean it.  I fully expected to see a gummed up float needle or some other obvious thing, but the carb was clean.  Actually, I could tell that it looked like someone had been in there before (some of the heads on the screws on the bowl were worn).  I took everything apart and cleaned it with carb cleaner, put it back together and it still acts the same.  I adjusted the idle fuel screw in and out to see if that would help.  I set it at idle, but it still runs rich and rough through all RPM ranges.  I checked the coil gap-- they're good.  The spark plugs look like they're fairly new, but they're wet with gas when I checked them.
From the Kohler manual, it really looks like the float bowl is too high.  It has a Keihin carb on it, but the Kohler manual has no info on what the float bowl should be set to.  Any idea what it should be?  I'm temped to just bend the tab down a little and put it all back together to see if it helps.
Like I said, it looks like someone's been in the carb.  I think they replaced the float or something and it didn't get set right.

Anything else I should check that would make it run rough and rich?  I heard from somewhere that the engine could shear the key and the timing could be off.  I haven't checked for that yet, but I will.

Thanks for the help.
-RC

smallengineshop

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #1 on: August 08, 2013, 01:37:24 PM »
How is the condition of the engine? Have you done a leak down or compression test? Does the engine emit black smoke when its running?

Check the air filter and housing. Make sure the air filter is clean and there are not obstructions in the intake. Make sure the choke is working correctly.

I wouldn't change the float height until you know where it should be set. What Kohler engine model is the your tractor using?
John 3:16 For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

rccolacc

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #2 on: August 08, 2013, 02:09:54 PM »
Overall condition of the motor is really good.  Have not done a leak down test-- will do that soon.

Air filter and housing are fine.  Motor runs the same with the filter on and off-- rich and smells like gas, so I know it's not a clogged filter. 

Choke is working correctly.  It was kind of the first thing I thought of when I was hunting for the smoking gun.  The butterfly is wide open when the choke is off-- it's not blocking the air at all.

I don't visibly see smoke when it runs, but there is significant soot on the exhaust.  If it's rich, it could really be 2 things-- the main jet is wrong or the float is set too high, right?  I'm ruling out the jet problem-- I would assume no one's changed it, but I'm not too sure on the float.

I emailed Kohler looking for specs on the float height.  The Kohler manual says to follow installation instructions on the new float, and since I don't have that, I don't know what it should be.  No response from them yet.

Thanks for the help.
-RC

rccolacc

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #3 on: August 08, 2013, 02:49:59 PM »
OK I just got an email back from Kohler.  The guy gave me the pdf of the instructions on the float replacement.  Looks like the float should be at 12mm, and it documents how to set it.

I'll try going through the Kohler thing here and see what comes of it.  I'll report back soon.

-RC

smallengineshop

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #4 on: August 08, 2013, 03:18:43 PM »
With a twin cylinder engine its important that both cylinders be in good condition and both cylinders produce the same compression. If one cylinder is in bad condition it can cause the engine to run rough, and a low compression cylinder will have poor combustion.

Here is a link to the repair manual for his engine:

http://kohlerengines.com/onlinecatalog/pdf/sm_32_690_01.pdf
John 3:16 For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

rccolacc

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #5 on: August 08, 2013, 03:41:00 PM »
Yeah I'll check the compression on both of them and compare. 

I've got the repair manual you linked there, but like I said it doesn't go through how to set the float height.  It just says to follow the installation instructions that come with the new float.  It does give some ideas on what could be wrong if it's running rich though, so it was helpful.

-RC

smallengineshop

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #6 on: August 10, 2013, 04:05:37 PM »
I don't think you can do a compression test on the Courage engine, because it uses a compression release. You'll have to do a leak down test, which is more difficult.

Let me know what you find out........
« Last Edit: August 10, 2013, 04:31:16 PM by smallengineshop »
John 3:16 For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

rccolacc

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #7 on: September 03, 2013, 04:48:21 PM »
Sorry it's been so long, but I've been busy with a work and other projects.

I did do a compression check on the motor.  Pulled the plugs and did the gauge on there.  I got the same reading on both cylinders-- about 180psi.  I'm calling them good.

I checked the float level on the carb per the Kohler pdf they sent, and it was set perfectly.

For kicks I replaced both spark plugs (only a few bucks).  Old ones were dark looking and smelled of gas, but they didn't look bad overall.  No change to the performance after that...

Checked the coil resistance in various places per the Kohler manual.  Both coils checked out OK-- ohm readings were within the margins.

I need to post a video of it next time I use it so you can see what I mean by running rough.  It really is like it's running on partial choke.  At this point since the float's good, carb is very clean inside, and the spark plugs are new, I'm thinking maybe the jets are wrong?  I have no idea if they've ever been replaced.  It does look like the carb's been taken apart at least once.  I'm thinking of buying the jets for the Kohler and putting them in just to weed out that possibility.  It'll probably be a fall project though.  Too busy now and need the lawnmower too frequently to be tearing into the carb all the time.

Thanks for the help again.
-RC

smallengineshop

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Re: Carb float adjustment on a Kohler Courage SV735
« Reply #8 on: September 08, 2013, 08:34:40 PM »
Did you ever get a chance to check and make sure the ignition is working correctly?

How do you know all the passages in your carburetor are clean? The outside/inside surface of the carb can look clean, but still have a blocked vent tube or other passage. The worst way to clean a carburetor is to spray it with carburetor cleaner so the visible surface is clean, than assume everything is clean and stop cleaning. The best way is to dunk the carburetor into a strong chemical cleaner and let is set for about 30 minutes (follow product instructions), than use compressed air to blow out all the passage's in the carburetor. You have to be careful when working with strong carburetor cleaning chemicals because they will destroy rubber and plastic parts.

You can also use an ultrasonic cleaner, but if you don't have one, than its easier to go buy a gallon of carburetor cleaner and dunk the carburetor.
« Last Edit: September 09, 2013, 10:49:45 PM by smallengineshop »
John 3:16 For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

The Small Engine Shop

Re: Carb float adjustment on a Kohler Courage SV735
« Reply #8 on: September 08, 2013, 08:34:40 PM »