1975 C-120 Automatic

[jbarnett 0]

I have a 1975 Wheel Horse C-120 Automatic. For some reason (doesn't happen all the time...) it will suddenly start slowing down gradually making a slight muffled sound while running at full throttle and eventually stall. After it does that I can usually start it right up. Sometimes it continues to do that and other days it never does it. Any thoughts as to what might be wrong? I installed a new fuel pump and new battery last fall. I put a new coil on it a couple years ago. I'm fairly confident it's not an electrical issue. Could it be that my points, alternator, or the regulator/rectifier is bad?

I've heard before that sometimes the values stick on Kohler K301 when they are warm and a little Marvel's Mystery Oil might help prevent this if a little is added to the gas. I haven't tried that.

It seems to lose power all of a sudden when it's running at full throttle. It seems (could be my imagination..) but if I only run it at medium throttle it never starts the gradual slowing down, then stalling cycle.

Any thoughts?

Thanks,

Jeff

[TT-(Moderator) 1,170]

:WRS:

The very first thing I would check is the gas cap vent.

Check for debris inside the gas tank too. (anything that could restrict flow)

[wheeledhorseman 579]

:WRS:

The second thing I'd check is the carburettor float bowl.

There could be some debris in there that's being drawn up into the jet on full throttle and which falls away again when the engine stops.

It's worth checking the jet itself as when something similar happened on my C-120 Auto the debris was actually sitting in the screwdriver slot of the jet itself.

Andy

[jbarnett 0]

Thanks for the suggestions. I'll definitely look into those things!

[buckeye25 0]

i would also check your points adjustment if they sliped a bit it wil run warm and sound muffled or tight kinda like it wants to make rpm and power but just cant do it but this only takes place at full rpm . the 10 hp k series in the 100 cubs were very bad at this during the last year of production. this might not be your problem but it sure sound familliar to me took four days of pulling my hair out and a few tears but finnaly figured it out.

[horsenut 1]

My dad bought one of these tractors in 75 and I still remember when it was delivered, runs like a champ to this day. These guys are right on, carb and points, if you've not replaced the points in awhile you may want to look into that as well...good luck and update this post...Real nice tractor for sure!