Long time lurker, I've always found great info on this board! I've got an issue now though that I just can't seem to nail down. I'm an aircraft mechanic by trade, I enjoy taking things that aren't quite running right and making them right again. I guess it's the challenge and satisfaction of getting it going. That said, this one's very challenging. I picked up a heavily used Hustler super mini Z last week. It has a Kohler CV740 that didn't run when I got it. We got her running, she idles great, but boggs under a load. Also, after about 30 seconds of running at full throttle the exhaust glows red.:yow!:
The cylinders and crankcase were full of fuel when I got her. I drained and flushed the crankcase and replaced the oil and filter, completely rebuilt the carb (complete disassemble, ultrasonic cleaned, and reassembled with a new Kohler kit), replaced fuel pump and fuel filter. It still leaks fuel into the intake when left over night, I'm assuming the seat in the carb is worn out as it was spotless before I put it back together. Not that big of a deal, it has a shut off vaive... I'll address it after I get her running properly.
After all of that, we got her running... only to find out about the power loss under a load and the glowing red exhaust. I'm assuming it's running lean and thought for sure it was related to the flywheel and a broke key. Pulled it apart only to find that the key is in good shape and intact. While pulling the flywheel, I noticed that it had rtv on the intake manifold to head connections instead of gaskets. Thought it might be sucking air through them so I cleaned them up and put proper gaskets on... no help either.
I did find that one of the coils had a stripped bolt and was loose enough to make contact with the flywheel. The ends of the pickup layers on that side had been flattened due to the contact which forced them to separate. Kind of hard to explain, basically that side of the pickup was about 1 1/2 times the thickness it should be. I put it in a vise and compressed the layers back together, cleaned the edge up and bought a longer bolt to reinstall it. It holds fine now, not sure if it's contributing to the issue or not though. I'll try the "pull one wire while running" method to see if it reveals anything.
After more research yesterday, I decided to pull the muffler off to see if it might possibly be blocked. It has a pretty good sized weld repair right where it glows red. I ran it very briefly without the muffler to see if it changed anything, still loses power under a load. I'm assuming the weld repair is a bandaid for a symptom, not the actual problem.
Next step is going to be a compression check... should have done that already.
This things got me pulling my hair out. It's not a bad mower. The hydraulics are great and really smooth. Hope I can get her straight, it's for my 15yr old son that cuts yards around the neighborhood.
Any help would be greatly appreciated!
D
The cylinders and crankcase were full of fuel when I got her. I drained and flushed the crankcase and replaced the oil and filter, completely rebuilt the carb (complete disassemble, ultrasonic cleaned, and reassembled with a new Kohler kit), replaced fuel pump and fuel filter. It still leaks fuel into the intake when left over night, I'm assuming the seat in the carb is worn out as it was spotless before I put it back together. Not that big of a deal, it has a shut off vaive... I'll address it after I get her running properly.
After all of that, we got her running... only to find out about the power loss under a load and the glowing red exhaust. I'm assuming it's running lean and thought for sure it was related to the flywheel and a broke key. Pulled it apart only to find that the key is in good shape and intact. While pulling the flywheel, I noticed that it had rtv on the intake manifold to head connections instead of gaskets. Thought it might be sucking air through them so I cleaned them up and put proper gaskets on... no help either.
I did find that one of the coils had a stripped bolt and was loose enough to make contact with the flywheel. The ends of the pickup layers on that side had been flattened due to the contact which forced them to separate. Kind of hard to explain, basically that side of the pickup was about 1 1/2 times the thickness it should be. I put it in a vise and compressed the layers back together, cleaned the edge up and bought a longer bolt to reinstall it. It holds fine now, not sure if it's contributing to the issue or not though. I'll try the "pull one wire while running" method to see if it reveals anything.
After more research yesterday, I decided to pull the muffler off to see if it might possibly be blocked. It has a pretty good sized weld repair right where it glows red. I ran it very briefly without the muffler to see if it changed anything, still loses power under a load. I'm assuming the weld repair is a bandaid for a symptom, not the actual problem.
Next step is going to be a compression check... should have done that already.
This things got me pulling my hair out. It's not a bad mower. The hydraulics are great and really smooth. Hope I can get her straight, it's for my 15yr old son that cuts yards around the neighborhood.Any help would be greatly appreciated!
D
