Mower runs at low RPM at full throttle.

ItsMaxton

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Hey all, I am somewhat new to the mowing scene and I actually use my mower to tow trash cans to the end of the long driveway more than mowing itself. I recently acquired a John Deere LX 279 mower with a Kawasaki V-Twin 17hp engine for free, quite a win in my books. The previous owner said the battery was dead but it ran great. I got the mower home and spent the rest of the day with a friend to try to get the mower working, we both have little mechanical experience and were not able to get it running after cleaning out the carb and testing the fuel system. (It turned over on starting fluid).

I ordered a cheap carb and cheap fuel pump off Amazon, I knew the fuel pump was pumping a good amount but I replaced it anyways, $12 part. ** I used the old gasket that connects the carb to the engine, and did a shotty job cleaning the old gasket that connects the carb to the intake manifold. Are these gaskets absolutely necessary to make a perfect seal? ** After replacing the carb I was able to get the engine to turn over and run. I had to adjust the idle to be quite high or the engine violently surges. When the throttle is turned all the way up, the mower runs okay, but I can tell its not full power. It almost stalls when the blades are engaged.

Here's the weird part: The choke is quite linear, I have about an inch of movement. If I nudge the choke up into the sweet spot, the engine comes to life and revs up quite a bit, to the point where It may be too high. I have seen a good amount of white smoke come out when I am running it at the high RPM with the slight amount of choke. Why does applying slight choke make the engine rev up? When choke is applied, it ignores the throttle and always revs high. Lowest throttle, add a little choke, full revs.

My carb has two adjustment screws, idle and a black adjustment screw that turns 180 degrees. I believe the black one is air/fuel. Turning it to both extremes makes no difference. Please help me figure this out! I am willing and able to preform any experiments that may lead to resolving this. I also have a second new carb if anyone believes the carb may be defective.
 

ItsMaxton

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StarTech

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Sounds like another will fit carburetor that is the wrong one for the engine has been put on. I just went a similar with a Briggs where the carburetor was setup for a smaller engine.

Sometimes you get what you pay for.
 

bertsmobile1

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It always amuses me that when there are hundreds of genuine on line mower parts retailers who know what they are selling and only sell parts of known good quality every one is adamant that they want to make the worlds second richest man richer by playing Russian Roulette purchasing parts from scammer central .
 

ItsMaxton

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It always amuses me that when there are hundreds of genuine on line mower parts retailers who know what they are selling and only sell parts of known good quality every one is adamant that they want to make the worlds second richest man richer by playing Russian Roulette purchasing parts from scammer central .
I have had good luck with cheap carbs in the past and I'm not interested in spending $200-$300 on a carb.
 

Scrubcadet10

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have you tried manually moving the throttle on the carb while it's running? to see if RPM increase?
 

Rivets

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Could be that the throttle cable is not adjusted properly. Try this, move throttle control to full speed, and then loosen the screw holding the cable in place. With the cable loose push it forward as far as possible and then tighten the screw. This will now be set at full throttle. Easier to check this first before throwing more money at it. I know that this manual is not for your engine, but Sec. 3 page 9, figure 29 has a good picture of the screw I’m talking about. https://docs.google.com/open?id=0B6NaqjIxWV1ySkZjTTA5TGltZEE
 
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