Magnum 16 HP

[Dave M 0]

I have a 416-8 with a Kohler Magnum 16 HP that starts to back-fire and run poorly after about 45 minutes of use. I rebuilt this motor with a fresh piston, rings and rod. The valves were ground and lapped as well. I'm wondering if the carb throttle butterfly shaft could be suspect. It has very slight play in it. I also have a 310-8 with a Magnum engine on it. I was thinking of swapping the the carb from it to the 16 HP motor. Does anybody know if the carbs are jetted differently from the 16 HP to the 10 HP? I have adjusted and re-adjusted the carb on the 416 and run Seafoam through several tanks of gas. The motor idles well and runs smooth when it's first started and under load. Thanks for any thoughts.

[TT-(Moderator) 1,162]

Check the gas cap vent - if you haven't already.

Or..........

Instead of swapping carbs between the 416 and the 310, try the ignition module (coil).

[Dave M 0]

Thanks, Terry. I had "rebuilt" my ignition module and so I thought it might be suspect; so, I replaced it with a new one. I no longer the think the problem is electrical. I can try swapping out the gas caps and go from there.

[WH nut 553]

Put a condensor on it

[TT-(Moderator) 1,162]

Put a condensor on it

Magnums don't have condensers. (or points) They have an electronic coil very similar to a B&S Magnetron unit.

[W9JAB 156]

:D

Do you have a good ground on the coil?

[Dave M 0]

Thanks for the replies. As TT pointed out, this is an electronic magneto ignition system, no condenser or points, and no typical ignition coil. All grounds appear to be good. The problem seems to be carburation. That's why I asked if anybody knew if the various HP motors (10hp thru 16hp) were jetted differently from each other, or if the carbs were the same (internally) on all the single cylinder Magnums. Thanks

[TT-(Moderator) 1,162]

The venturi sizes (probably) are a little different, but unless your carbs are non-adjustable main jet versions, you should be able to make the 16 run fine with the carb from the 10.

[b-80boz 0]

not trying to but in but you could have a pin hole in the float ..... :D

[Pirate 0]

If you have a hole in the carb float, you will have gas pouring out the carb. I have that problem right now on my 14 magnum. Worn inlet needle. Carb kit is on the way. My float was good. You can shake it and see if there is any gas in it.

Good luck with it, and be sure to post the cure.

[Dave M 0]

I appreciate all the replies. My son used the 416 to cut the grass yesterday and it sounded okay up until the end when he limped it in and got on the JD 316 to finish the job. He had cut for a couple hours on the 416. It didn't sound right when I heard him bringing it in. When I asked him if it had started running poorly toward the end, he said it was just out of gas. The tank was very low and it was probably starving on the inclines. Anyway, I'm thinking it might be finally "clearing-out" with the Seafoam treatments I have been giving it and my last tweaking of the carb. I'll run a couple more tanks of fuel with Seafoam and see if it continues to improve. Hopefully it will. When all this started after the rebuild, I had to question my rebuiding methods even though I did not rebuild the carb. Thanks again for all the help.

[dgjks6 8]

I appreciate all the replies. My son used the 416 to cut the grass yesterday and it sounded okay up until the end when he limped it in and got on the JD 316 to finish the job.

:D