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Discussion Starter · #1 ·
ok here is the deal. i was cutting grass and the mower ( cub slt 1550) suddenly seemed like it was starving for fuel. (common problem for me because there is a rock in the tank.... long story) so i pulled fuel line at the tank and had good flow. so i tried to restart as always and the engine just turned over with out firing. i then pulled the air filter and put some gas in the carb. still it didn't fire, checked the oil, checked the oil sensor connection, checked for a spark at both ends of the plug and it was good. i even tried to squirt some gas directly into the cylinder and still couldn't get it to fire. turns over just fine but its putting a small whitish puff of smoke or fog? out of the muffler when i turn it over, ( engine was still warm from running) i have never seen this before. i tried turning the flywheel by hand from the cover on top of the engine and had resistance on what im assuming was the compression stroke. i could also hear the hissing sound of the compression release when the valve opens? so i am at a loss having never had this problem before. i pulled the carb down about 2 months ago and cleaned the jet before its first use this year and its been running great. but the no fire after i pour gas in the carb has me puzzled. especially since i am getting spark...i need to know where to go now. flywheel key? valve adjustment? is it real easy for these kohler courage 25's to jump timing?. some good advice would be greatly appreciated.

thanks in advance. :howdy:
 

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I would take a bet that the valves are out of adjustment. If you go out to the garage and start your mower tomorrow when it is cold, it is likely to start right up. If it does, your issue is valve adjustment. Ethanol gas burns hotter and causes the valves to hammer the valve seats further into the head as the engine runs over time. After enough hours the valve seat has been pressed into the head 0.010" or more causing either the intake or exhaust valve or both from seating. Lapping all 4 valves and adjusting the valves will correct your problem! A good solution to the problem is to run ethanol free gas! If that is not available, the removal and replacement of the muffler with a straight through or less restrictive muffler will increase valve life by reducing exhaust gas temperature.

Chris
 

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:ditto: I would start by just adjusting the valves to see if that will get it going. Valves need to be periodically readjusted, ethanol or no, and that may be all that's wrong.
 

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Discussion Starter · #4 ·
i tried to start it today and it did manage to sputter a little bit but not at all trying to start. i will try to inspect rocker arms and valves tomorrow when i get a chance but im not 100% sure what im doing. i just going to pull the little valve covers off and see if anything jumps out at me as being obviously wrong. but do any of you have a step by step guide for doing it? any special tools im gonna need aside from a feeler gauge? also is there anything i need to watch out for thats really easy to mess up?
 

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The only tools you need to adjust the valves, other than the feeler gauge, are the correct size wrenches. If the valves are out of spec, you won't see anything wrong by just looking at the rocker arms. We're only talking about the difference of a couple hundredths between the rocker arm and the top of the valve spring. If you need any help, feel free to ask!:ThumbUp:
 

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Discussion Starter · #6 ·
ok i need help. i have no idea what im doing. i pilled the valve covers easy enough. it seems to me the rocker arms dont push directly on the valve spring rather they push on the end of the valve itself. i cannot positivly tdentify it but i am assuming there is some kind of keeper of the end of the valve that keeps the spring tensioned and in place? is this correct? there seemed to be a 1/8 to 1/4 gap between the top of the spring and the valve end of the rocker arm.. is that wrong? im gonna take a pic in a few minutes so you can see what im talking about. its just the thing that worries me is the sudden change from running good to missing to not starting at all. i was mowing for about an hour with out putting much of a strain on the mower. makes me feel like something failed. but i guess first things first i will check the valves to eliminate that as a problem.. gonna get my buddy to bring me a set of feelers this afternoon. the only thing i need to know is which screw to tighten/ loosen to do the adjustment the allen head set screw on the outer push rod side of the rocker or the nut on the inner side of it. or do i have to loosen one tighten the other and tighten the other one to set it?
:help:
 

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Discussion Starter · #8 ·
valves seemed tight, like there was no gap at all. like the push-rods only went down far enough to let some but not all the tension off of the valve tips.
 

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The valve clearance for your engine is .004-.006 inches. The reason that the rocker arms seem really tight is because they are acting on the valve springs.(What I mean is that when the engine last stopped, the rocker arms were in the act of compressing the valve springs) What you have to do is rotate the engine until the rocker arms release tension off the valve springs.
 

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Discussion Starter · #10 ·
yeah i bumped the starter to get the valves to the closed position and twisted the flywheel to get it to the position where i had slack on both rockers. im guessing form the spec's you posted that the little bit of play i have might be way to much. guess i have to get a set of feeler gauges my buddy couldn't find his. so i guess the next step is to pull the plug and find the top of that compression stroke and check/adjust my rockers from there. what i also need to know is that to loosen/tighten to do the adjusting. is it the bolt that mounts the rocker to the pedestal? or is it the big ste screw/nut on the pushrod side of the rocker. and im not real sure of the procedure for doing the checking/adjusting. it seems pretty straight forward but i would like someone to explain it to me in detail so i can avoid some of the mistakes that i can make.
 

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There is no need to remove the plugs and find top dead center.
To adjust the valves, rotate the flywheel so that the intake valve is all of the way up. When the intake valve is up, the exhaust valve is down. At this time, check the valve to tappet clearance and make sure that it is the same as the book. If it is not, it is time to break out some tools and adjust the valve. Remember, a little adjustment goes a long way, 0.001" is not very much, and may be just 1/10th of a turn of the adjustment nut. Once properly adjusted, and double checked (For ex, If the valve clearance is supposed to be 0.005", a 0.005" feeler gauge should slide in, but a 0.006" feeler will not) then move onto the other valve. Turn the flywheel over until the exhaust valve is up, which would mean the intake valve on that cylinder is down. Adjust the intake valve in the same manner. Remember, intake and exhaust valves have different valve lash clearances, consult your Kohler manual for the proper clearances. Once all four valves are adjusted, make sure the valve cover gaskets are in good shape, and torque the valve covers back in place. Once finished, the engine should start and run perfectly!

Chris
 

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Discussion Starter · #15 ·
set valves and inspected the key way. both are good.. so im at a loss here. maybe i have a crack in the block. can they sleeve this engine?
 
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