14hp kohler-ok when cold-bad misfire,no rpm after gets hot-HELP!

[165jim]

just had a dealer serviced 914 ac w/ a 14 hp kohler "k" series [1983] single cylinder- they rebuilt carb, and done complete tune up. they bring it out ,runs great when its cold.after running 2-3 minutes under a load ,moter gets hot misfires real bad, loses rpm's,engines so hot -theres smoke going out of left side right under the carb now.exhuast is on opposite side. they took it back a 2nd time said it didnt have the right rpm;s to work governer right. and put on a new throttle cable, brought it out , unloaded it when cold,ran fine.today runs like before ,hot, misfife,etc:. it reminds me of a ford 8n tractor we had on the farm-ran like it was out of time or bad points.could it be a bad coil or condenser?-thanks for any suggestions!-jim

 

[wrenchturner]

I had the same problem before. I had bought a lawn tractor with a Kohler engine from from my brother in law. He said it ran good. Well, when I brought it home and mowed with it for about 30 minutes it would backfire and quit running. After about 15 minutes it would start fine and then again after about 20 minutes it would back fire and stop again. During the cool down time I would just drink a cold beverage. One Saturday, his 2 kids were down for a visit and of course while mowing it backfired and quit. As I was walking into the house for a cold beverage his kid says "It does that". Hummm? Well, I did find out what the problem was. The exhaust valve has carbon built up on the stem. As the valve gets hot, it expands then sticks into the valve guide. With the exhaust valve open and the piston going down and pulling the air and fuel into the cyinder it is also pulling the hot exhaust gasses back in which ignite and thus causing the exploded gasses to go out both the intake and exhaust ports.

I would clean the guides and install new valve springs.

Wrenchturner

 

[165jim]

thanks for your comments wrench turner! hoping others could offer any ideas-after starting the moter cold it only takes3-4 minutes run time under a load for it to start running bad. it seems to heat up really fast-jim

 

[oldnslo]

On my 12 HP Kohler it was a bad ignition coil. Once it got warm it would idle reasonably well but would not rev up nor work under any load. This is the automotive style coil points and condenser system.

 

[Barry 1]

The crankcase breather/vent is under the carb.That isn't smoke from getting hot,it's blowby from being worn out.You need a rebuild. I agree with the valves sticking,and carbon gets under the valves and hold them open,probably causing your problem.

 

[165jim]

got it back from dealer today,finally runs right. coil was bad,and burned up the points,and condenser. so i paid for 2 sets of points -condenser,total for this was $137 .i would have thought they would have checked the coil the first time,it took 3 trips to the shop to fix it.i dont know if i will ever deal with thses people again.mower runs good but at idle stills runs rough/ sputters a bit.thank to those that made comments.-jim

 

[darg]

Might try star tron , start, and a spray by blaster products ,they seam to work real good , I have a 77 wheelhorse C160. Also a 12hp mag that I recently bought.. and used the products . Good luck

darg

 

[165jim]

update: we have mowed the yard 3-4 times since it came back from mower shop-have run 8-9 hours,seems to be it's happy self again,has run good.again, thanks to all that replied here.-jim

 

[w0dlr]

I have a Cub Cadet 149 with the 14 hp kohler single cylinder engine. I bought a block had it bored and the crank turned. After putting it back together it will run a while until it gets hot and then misses like it is out of time. My questions is this, will any 12 volt coil with the internal resistor work on this engine? Also, what should the voltage be at the points. My repair shop man tells me the voltage there should be 8.5 volts. Mine reads about 16 volts. I fear I have already burned the points with this higher voltage. Do I need a coil, and will any 12 volt coil work, or how about the voltage regulator? It has been a bottomless money pit and it still is just a yard ornament, and a hard looking one at that.
Any suggestions
Dave in Kirbyville, Mo

 

[Chris149]

You cannot use any 12 volt coil, some have built in resisters to prevent such a problem