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Discussion Starter · #1 ·
I'm a new member. Is it normal to have to use the choke breifly to start the kohler 14hp engine when it is hot on my 140? When I have been mowing and shut if off and restart it won't fire until I flip the choke up. I put a carb kit in and adjusted the high idle screw and low idle screw but it still requires the choke on a hot start.
 

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Hi Mike, welcome to the WFM forums. Typically older Kohlers in good condition will start without choke when warm or hot. But engines with slightly lowered compression due to worn rings or valves, a weak starter, weak battery, or carburetor air leaks will usually need a little choke to start. The most common air leaks are around a worn throttle shaft or at the carb-to-block gasket. Throttle shaft repair kits are available to fix worn throttle shafts, and whenever a carburetor is removed the mounting flange should be checked for warpage and lapped if necessary. Most flange warpage or distortion is caused by over tightening the mounting bolts combined with an old gasket. A new gasket should always be used after a carburetor is removed.
Stan
 

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Discussion Starter · #3 ·
Thanks for the tips Stan. I do notice that the starter on my 140 doesn't turn near as fast as the starter on my 110. I will put my compression tester on it tonight to rule out the worn rings & valves. The throttle shaft doesn't feel like it has any play in it. I also have a new carb to block gasket on it.
 

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Mike, after years of use it's normal for the starter commutator and brushes to be burned and pitted enough to reduce output by 20% or more. Another possible cause of weak starting is poor connections of the ground and starter cables. A quick check is to remove the spark plug (but keep the lead connected and lay the plug on the head) and crank the engine for a good 15 seconds. Then feel the end of each cable for any indication of heat. do this with the ground cable and the (+) cables between the battery, solenoid and starter. Any noticeable heat indicates a poor contact. By the way, a thermal temperature sensing device such as a Raytek MiniTemp makes this a quick and easy job.
 

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Gentlemen,

My '94 425 idle has a slight miss/stumble to it-at idle or fast idle and in between.

I am noticing that when I unplug the right spark plug wire, the engine almost shuts down. On the left wire, it doesn't react (stumble) as much.

-Valves adjusted to spec.
-new carb
-new coils/wires/plugs
-compression mid 170s on each cyl, no oil consumption or smoking.
-Igniter replaced, and the time delay module as well.

perhaps-(Pulsar/stator)?

Can anyone here offer what the solution is? I'm stumped.

Thanks,

Dave.
 

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About all I can offer is a quick, no cost test. Swap the plugs side to side and see if you get the identical reaction when removing each wire while running. If the opposite cylinder is the weaker one, pull both plugs and make sure the gap is exactly the same for both. Test again.
I believe you will find a test procedure in the Kawasaki L/C Engine manual for the pulsar coils that does not entail removing parts. I don't think the stator would cause this, but could be wrong....again. lol

tommyhawk
 

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Well, that's about it for me. I was thinking about corrosion in the coil towers, wires, or the plastic plug ends. They may have a resistor built in to them by the way. But, if all new, you've covered that. There is a very small chance that the retaining screw on that pulsar coil is loose.

I see you live in Florida. Is there still grass to mow? Do you feel a big loss of power with the mower deck engaged? If so, one cylinder is definitely not firing properly.

tommyhawk
 

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Tom,

I Stopped mowing about 3 weeks ago.

Will resume 1st or 2nd week of April.

I use this time to enjoy the cool weather and work on the tractors, and outdoor projects.

Anything less than 3/4 throttle will shut the engine down. I use the 60" deck.

Also engine is at 1080 hrs. Vacuum at the dipstick is appx 1 inch.
 

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Dave,

I agree with Tom that the chance of a loose or bad pulsar coil is slim or none. The fact that the problem is isolated to the left coil definitely sounds like an electrical problem.

To eliminate any chance of the TDM or associated wiring, disconnect the yellow-white wire to the left coil and connect a jumper from the coil terminal directly to the positive terminal of the battery. Start the engine and see if the problem has disappeared.

The strange symptom is that the problem does not happen at full throttle?? A problem with the pulsar should happen over the full range of engine RPM.

Does this engine have a plastic or steel camgear?

George of Buford
 

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George,

An update is in order.

I worked on it this morning.

Manifold intake bolts were essentially hand tight!

I also checked the gap on the NGK spark plugs. I had assumed the plugs were fine out of the box. Out of the box they are appx .010. The spec is .030.

Engine seemed to idle better.

However when the plugs were out I noticed that the head of the left piston seemed to be "wet" while the head on the right piston seemed dry. Both piston tops (viewing thru spark plug hole) had carbon, but could stIll see metal.

Thoughts?
 

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Dave, I don't recall that you mentioned the number of hours on your 425. My 445 had about 2200 hours when it started having issues. It turned out to be a bad head gasket. Antifreeze made its way into the combustion chamber. Sometimes it would fire that cylinder, other times not. When it did, it looked like lots of smoke - but it was actually steam. My piston looked wet until replacement of the gaskets.
 

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Dave,

A little history of this tractor would help. Since you asked me for side panels, I assume that you bought this tractor used. Loose intake bolts tell me someone was inside this engine looking for a problem.

I believe Chuck is correct. This Kawasaki engine has a well known problem with leaking head gaskets on the left side. I have bought a couple with that problem cheap because the owner did not want the repair expense.

I am pretty sure we can rule out an ignition problem with the wet condition of the left cylinder. Does wet mean like water or fuel? Fuel would evaporate much quicker than water/antifreeze.

DO you know if this engine has a plastic or steel camgear? Does the engine have any other telltale signs of having been disassembled? Gasket sealer etc. Did you check the compression with the engine warm or cold? I would have expected the left to be a little low on compression.

I rebuilt a FD620D that would run great until it was warm and under a load it and would just completely die. It did not sputter, it was like the ignition was turned off. I went through everything electrical you did and more. Finally I replaced the carb and it ran great. I cleaned the old carb 6-7 times, but there was something that caused the problem. I do not spend much time on WHY questions once something is fixed. I thought I was pretty good at diagnosing engine problems until I ran into this engine.

George of Buford
 

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Chuck-current hrs are 1080. The wetness appears to be oily. BUT I am going to double check that. Occasionally I get a light puff of smoke when starting cold. Once hot, no smoke and the exhaust has little odor to it. I also can say the exhaust is dry.

George- I have no owner history on the machine. Funny you bring up if anyone has worked on the engine. I really don't see any evidence of the case being disassembled, tool marks , RTV etc. Last time I checked compression on cylinders both were within a few lbs and mid 170s, Checked warm. The carb is brand new.

I am going to try to upload pictures in the AM.

A head gasket is cheap...I'm wondering if I should pop the left head off and see what I find or don't find.
 

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Leak down cylinder test results:

Cylinder 1= 65% (left cylinder)
Cylinder 2= 53% (right)

Those were the most consistent results I could get.

Air escaped thru uncovered valve covers, (filler tube when covers on) none thru carb or exhaust.

No bubbles in radiator, no leaks around the heads either.
 
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