Turbodriven
Active Member
- Joined
- Aug 18, 2023
- Threads
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- 84
Hey everyone. I'm new to zero turns but very mechanical in experience (ex Navy fighter jet mechanic).
Got a used 2005 260z (Kohler CV740 Command Pro 27) for cheap that starts and idles (and throttles up and down) perfect. Sounds good sitting still. Even starts mowing like a bat out of hell for the first few seconds. But then after 20 feet of moving at speed (and even worse when blades are engaged) the motor quickly starts winding down to about 20-30% rpms (or so it feels) and barely mows. Like someone stuck a banana in the tailpipe. If I disengage blades and pull back the controls to a stop, the rpms pick back up and she idles/sounds normal again. But then the behavior returns when I push the sticks forward.
I put new plugs in it and after mowing for five minutes I pulled both plugs out and they were both dry and thick black (rich).
1. This behavior remains unchanged after installing a brand new carburetor, new fuel pump, fuel filter, spark plugs, air filter, and fresh gas.
2. Compression tests on cyl1=170psi and cyl2=175psi
3. There is no smoke in the oil dipstick (crankcase) after running and the oil level is correct.
4. Behavior does not correct when unscrewing the gas cap (*even though "lean" doesn't appear to be the issue)
5. Governor linkage was set per specs when I installed the new carb.
6. Battery is good and I hooked up my multimeter while running and it maintains 13.x+ volts throughout the whole behavior. Also, there is no spikes when engaging PTO clutch. That system appears to be operating normal??
7. I had the deck off last week and all three spindles seem to spin fine.
I'm not sure what else to think. The basic behavior is that the motor slows down under load. So either the normal load is affecting something wrong with the motor, or an abnormally heavy load is too great for the healthy motor.
Any ideas on what to check or fix to get this right?
Got a used 2005 260z (Kohler CV740 Command Pro 27) for cheap that starts and idles (and throttles up and down) perfect. Sounds good sitting still. Even starts mowing like a bat out of hell for the first few seconds. But then after 20 feet of moving at speed (and even worse when blades are engaged) the motor quickly starts winding down to about 20-30% rpms (or so it feels) and barely mows. Like someone stuck a banana in the tailpipe. If I disengage blades and pull back the controls to a stop, the rpms pick back up and she idles/sounds normal again. But then the behavior returns when I push the sticks forward.
I put new plugs in it and after mowing for five minutes I pulled both plugs out and they were both dry and thick black (rich).
1. This behavior remains unchanged after installing a brand new carburetor, new fuel pump, fuel filter, spark plugs, air filter, and fresh gas.
2. Compression tests on cyl1=170psi and cyl2=175psi
3. There is no smoke in the oil dipstick (crankcase) after running and the oil level is correct.
4. Behavior does not correct when unscrewing the gas cap (*even though "lean" doesn't appear to be the issue)
5. Governor linkage was set per specs when I installed the new carb.
6. Battery is good and I hooked up my multimeter while running and it maintains 13.x+ volts throughout the whole behavior. Also, there is no spikes when engaging PTO clutch. That system appears to be operating normal??
7. I had the deck off last week and all three spindles seem to spin fine.
I'm not sure what else to think. The basic behavior is that the motor slows down under load. So either the normal load is affecting something wrong with the motor, or an abnormally heavy load is too great for the healthy motor.
Any ideas on what to check or fix to get this right?
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