mattd860 161 #1 Posted February 14, 2014 My 418 with the 18hp Kohler motor sputters or misfires under load. The motor starts and runs great otherwise. While plowing snow, as soon as I start pushing the snow the motor sputters and loses power but keeps running. It will even keep pushing the snow but just slower. I experienced this problem in the Fall so I changed the plugs, cleaned out the carb, and de-carboned the heads. There was a massive amount of carbon buildup on the front cylinder head. It was caked all around the intake and exhaust valves and really really built up between the valves and the cylinder. I'm talking large CHUNCKS. I cleaned it all up nicely and it ran a little better but still skipped and sputtered under load. Now it's getting progressively worse. Could it be running really rich? The exhaust smells very rich but I haven't adjusted the carb needles. What else would cause the carbon buildup on the front cylinder and possibly the sputtering & loss of power under load? Share this post Link to post Share on other sites
WH nut 553 #2 Posted February 14, 2014 If you already changed plugs I would look at the plug wires, sounds like they are breaking down. In the dark spray the wires with water from a spray bottle and put it under load and watch the fire works. Im betting you will see them arching 3 Share this post Link to post Share on other sites
CRE1992 135 #3 Posted February 15, 2014 Matt you might have to adjust the valves. Or it is time for new valves someone told me on the magnum twins you have to file or grind the valve stem in order to adjust them. I do not know how true this is but it could cause problems if they are not seating all of the way. Also when was the last time you replaced the fuel lines or the fuel filter. Share this post Link to post Share on other sites
ARK 9 #4 Posted February 18, 2014 Good ides, start using Seafoam in gas tank for a few tankfuls, check plug(s) for colour and gap, a little less than book states. Check gas lines if rubber, look for deterioration. Share this post Link to post Share on other sites
Wheel-N-It 2,967 #5 Posted February 19, 2014 Do check the wires just in case. I had to replace the wires on my 417 because of age and deteriation. Share this post Link to post Share on other sites
mattd860 161 #6 Posted February 21, 2014 Replaced the coil and it's working well. The wires were chipped and worn in various spots especially where they passed through the slit in the blower housing. Thanks 1 Share this post Link to post Share on other sites