Why so lean? Kohler

J

Jmoney7269

Joined
Aug 15, 2018
Messages
181
Location
Texas, United states
A friend of mine i do crossfit with brought me his mower to do a complete tune up after he heard how much better they run when I'm done. He said it runs so hot that he can feel the heat on the back of his neck when mowing. Pulled the plugs which were the wrong China plugs and installed the right ones (rc12yc). Then I removed the Welch plug that houses the air/fuel screw. It was all the way turned in. The engine was happy at 3.5 turns. Set the valves which were where extremely out of spec, and set the mechanical governor to 3600rpm with the blades on. Changed the oil to a 40wt. Runs like a totally new machine. The epa is literally ruining these engines running them so lean.

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Jmoney7269 said:
A friend of mine i do crossfit with brought me his mower to do a complete tune up after he heard how much better they run when I'm done.
...
Runs like a totally new machine. The epa is literally ruining these engines running them so lean.
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Good on you. Your friend owes you a beer or two.

Your last comment reminds me of motorcycles. I had a '99 Honda Magna with the same problem. New from the factory it had a very noticeable response flat spot in the midrange RPM with lean surging. With its CV carburetors, 2 sizes larger main jet and 2 extra shims on the needles made it run the way the engineers intended, with better throttle response, stronger power and still great fuel economy.
 
Jmoney7269 said:
A friend of mine i do crossfit with brought me his mower to do a complete tune up after he heard how much better they run when I'm done. He said it runs so hot that he can feel the heat on the back of his neck when mowing. Pulled the plugs which were the wrong China plugs and installed the right ones (rc12yc). Then I removed the Welch plug that houses the air/fuel screw. It was all the way turned in. The engine was happy at 3.5 turns. Set the valves which were where extremely out of spec, and set the mechanical governor to 3600rpm with the blades on. Changed the oil to a 40wt. Runs like a totally new machine. The epa is literally ruining these engines running them so lean.

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I had an echo chainsaw my brother gave that was like that. screws turned in all the way. No wonder he said it was the most overpriced POS ever lol 10 minutes and she was running like new.
 
Lawnman23 said:
The twin banger Courage’s are fine, it’s the single cylinder bucket engines that have a poor track record.
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The only engine I’ve ever had fail was a single cylinder Courage. Whole block started to crack, then sent a rod through the side. The thing was babied too with early oil changes, filters, and everything else.
 
MurkyAsparagus said:
The only engine I’ve ever had fail was a single cylinder Courage. Whole block started to crack, then sent a rod through the side. The thing was babied too with early oil changes, filters, and everything else.
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I think they replaced the courage with something else. Forgot what it was though
 
ripcord said:
2 Kohler Command singles for me and man are they reliable and strong. My 36" walk behind mower started on the second pull this spring after sitting all winter. Putting E0 in them doesn't hurt.
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Every manufacturer has a dud or two along with a few winners
 
MRC01 said:
Good on you. Your friend owes you a beer or two.

Your last comment reminds me of motorcycles. I had a '99 Honda Magna with the same problem. New from the factory it had a very noticeable response flat spot in the midrange RPM with lean surging. With its CV carburetors, 2 sizes larger main jet and 2 extra shims on the needles made it run the way the engineers intended, with better throttle response, stronger power and still great fuel economy.
Click to expand...
I do a lot of carburetor tuning for kawasaki brute force 650-750s. I go up from 38 pilot to 40, and go up two jet sizes as well on the mains. But here is a little trick I learned tinkering with these things. I also cut off two coils of the CV spring and drill a very small hole in the metal part in the center. After it's all reassembled, you can literally start the machine cold with no choke. Also when warmed up, you can slam the throttle from idle and it doesn't bog at all. Just instant power. I have an old school mercury carb sync tool and you would not believe how unbalanced some of these engines are. Some are off over 20hg
 
Last edited:
Jmoney7269 said:
I do a lot of carburetor tuning for kawasaki brute force 650-750s. I go up from 38 pilot to 40, and go up two jet sizes as well on the mains. But here is a little trick I learned tinkering with these things. I also cut off two coils of the CV spring and drill a very small hole in the metal part in the center. After it's all reassembled, you can literally start the machine cold with no choke. Also when warmed up, you can slam the throttle from idle and it doesn't bog at all. Just instant power.
Click to expand...
Yeah I didn't even know they could run with the jet screws turned in all the way
 
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