Bad Boy Blues

A

-AC-

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Hey Gang, like a lot of people I joined this forum trying to get some advice. I hope that isn't offensive, but at least I'm honest about it. Here's my scenario:

I have a 2011 Bad Boy ZT-60 that I bought at TSC in the spring of that year. I intentionally bought more mower than I really need to both speed the job of mowing and (hopefully) get long life out of a $5000 mower by not using it that hard. I mow around 1.5 acres and four years later the mower has 100.5 hours on the clock. This mower has the Kohler Courage Pro 27hp engine. I have changed the oil with quality dinosaur juice every year, and also cleaned the air filter, hit the grease zerks, etc. This mower certainly has not been abused.

My dilemma:

The year before last, near the end of the season, I had a few "spells" of power loss. The motor would bog and threaten to stall if I did not pause and let the rpms come back up. This would only last for 20-30 seconds and then would completely resolve itself, and mow like normal. This happened a few times but rarely, and I thought perhaps I had some bad fuel. Last year I got it out and it worked fine for the first half of the summer, but the bogging issue returned mid-season and got progressively worse. I put it away puzzled last year, and this year it's almost unusable. I should mention that I suspected either air or fuel starvation, but replacing the plugs, the air filter, and the fuel filter did not help. The plugs looked normal. I now also have an additional symptom. When I pause to let the rpms catch up, and shut off the mower deck, I get a lot of gray/blue smoke as the motor revs up. It lasts for a while (30 seconds) before clearing up, with the motor spinning at 3350rpm. Aside from the filters and plugs, I have also checked the pto torque to ensure that it isn't overly tight and making the motor work too hard, but it was fine. I can spin the blades easily by hand, so I know it isn't a question of the spindles being seized and taking too much motor to spin. The choke and throttle cable seem to move appropriately and not bind.

The blue/gray smoke and lack of power made me fear the worst, and I thought perhaps I have blown the motor, either having ring/cylinder problems or perhaps a burned valve. But this evening after mowing (incredibly poorly and slowly) I got fed up and pulled the plugs. Neither side shows evidence of oil burning (if anything they look a tad lean) and the right side (passengers side) was wet. It wasn't oil so I assume it's gas, but I have no sense of smell so I really couldn't tell. I then did a compression test and I have 180psi at both sides. This tells me the motor isn't blown, I believe. So, I am now contemplating some arcane situation where I am actually flooding the engine due to a carb issue, and this is making it bog down and also making the right side plug wet. But, I am not aware of a scenario where the motor gaining rpm's after a flooding situation would make it smoke gray/blue. Black sure, but not blue. So, that's where I'm at.

Any advice on this would be GREATLY appreciated. Having a 100-hour-old $5000 mower that doesn't work is gnawing at my soul...

Thanks to all,
AC
 
I

ILENGINE

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From your situation is sounds like you are getting temporary flooding of the engine. The extra fuel will wash the oil off the cylinder walls causing blue/grey smoke. The other thing to check is the oil level. Kohler had some past issues with intermittent smoking on inclines due to the oil level being too high.
 
G

gainestruk

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A good carb cleaning might fix your problem, did you leave gas in carb over the winter ?
 
A

-AC-

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Well, with the mystery solved, I felt I owed it to the forum to own up and admit my stupidity. This is highly embarrassing, but here goes:

So, after removing and going through the carb completely, I found no gum, gitch, or other smoking barrels. I used my parts washer and compressed air and really went through it, removing the jets and using a small medical stylus to chase every passage. This made NO difference. I was perplexed and frustrated, so I called a buddy to come over and think (drink) about it with me. It took him about 2 minutes to realize what I was totally missing. The thing was only running on one cylinder. Duh.

Now, in my (weak) defense, I always worked on it "cold" and then test drove it. So I didn't have any cylinder heat (or lack thereof) to gauge it. But really more than that, I never thought I could be dropping a cylinder mostly because how decently the thing runs on one lung! I have had several twin cylinder motorcycles over the years (BMW, Harley, BSA, Triumph, Honda, Yamaha) and three snowmobiles with twins (Polaris and Ski Doo) and NONE of them would start well, idle smoothly, and rev up cleanly running on only one cylinder. I wouldn't have thought it possible. This mower always started promptly and idles like a dream, even at low throttle. It would run down the road smoothly, only when I engaged the deck and started to mow would it lose power. I would have bet $100 that it was running on both sides. It HAD to be, based on how it ran. Live and learn...

So anyway, after figuring out I was down to one jug, it didn't take me too long to figure out that I had no spark on the right side, and then some simple Fluke meter work showed me it is a bad coil. I double-checked this by moving the coils side-to-side, and the no-spark condition moved to the left side. So, my mystery is solved. But of course, there's a new wrinkle to overcome. The original coils are no longer made or used. They have been replaced with a new style that doesn't use 12v to "excite" the coils, but is a more traditional magneto system. So, I can't just replace the coil, I have to do a modification to both sides. However, it looks like I can get both new coils and the new wiring for under $100 (actually, I've seen as low as $81 on Ebay, but I'll probably order from someone more brick-and-mortar). I guess they had enough trouble with these coils to go to a simpler design.

So, that's the scoop. I guess the biggest thing I learned is that a Kohler twin can run really really smoothly on one cylinder, but it doesn't mow worth a damn that way...

Thanks to all who took an interest,
AC
 
I

ILENGINE

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The Kohler spark advance system has been through about 8 different setups since the beginning. Every time the supplier changed the whole system changed. The DSAM box is no longer available, or the modules themselves. So everything is being converted to the DSAI system. I have done 2 conversions over the last couple years, including one on a 27 hp this spring. The hardest part about the conversion is removing the blower housing. The DSAM box goes bye bye, the hot wire going to the old coils gets clipped and no longer used. You may have to replace the connector on the wiring harness to plug into the new kill wire, and then replace the modules. You are done at that point.

the new modules are magnetically self powered with spark advance which is what the DSAM box did but used battery power.

A few years ago my uncle rolled into the driveway with his motor home for a visit, and had just come back from talledaga speedway and said the generac generator with the 16 hp vanguard briggs engine was using about a quart of oil every 8 hours. They had run it a week like this. He opened the access door and hit the start button, and I immediately said you are running on one cylinder. He said how do you know, and I said i could hear the miss. Replaced a bent pushrod, and hasn't used a quart of oil in the last 600 hours.
 
S

shiftsuper175607

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-AC- said:
Hey Gang, like a lot of people I joined this forum trying to get some advice. I hope that isn't offensive, but at least I'm honest about it. Here's my scenario:

I have a 2011 Bad Boy ZT-60 that I bought at TSC in the spring of that year. I intentionally bought more mower than I really need to both speed the job of mowing and (hopefully) get long life out of a $5000 mower by not using it that hard. I mow around 1.5 acres and four years later the mower has 100.5 hours on the clock. This mower has the Kohler Courage Pro 27hp engine. I have changed the oil with quality dinosaur juice every year, and also cleaned the air filter, hit the grease zerks, etc. This mower certainly has not been abused.

My dilemma:

The year before last, near the end of the season, I had a few "spells" of power loss. The motor would bog and threaten to stall if I did not pause and let the rpms come back up. This would only last for 20-30 seconds and then would completely resolve itself, and mow like normal. This happened a few times but rarely, and I thought perhaps I had some bad fuel. Last year I got it out and it worked fine for the first half of the summer, but the bogging issue returned mid-season and got progressively worse. I put it away puzzled last year, and this year it's almost unusable. I should mention that I suspected either air or fuel starvation, but replacing the plugs, the air filter, and the fuel filter did not help. The plugs looked normal. I now also have an additional symptom. When I pause to let the rpms catch up, and shut off the mower deck, I get a lot of gray/blue smoke as the motor revs up. It lasts for a while (30 seconds) before clearing up, with the motor spinning at 3350rpm. Aside from the filters and plugs, I have also checked the pto torque to ensure that it isn't overly tight and making the motor work too hard, but it was fine. I can spin the blades easily by hand, so I know it isn't a question of the spindles being seized and taking too much motor to spin. The choke and throttle cable seem to move appropriately and not bind.

The blue/gray smoke and lack of power made me fear the worst, and I thought perhaps I have blown the motor, either having ring/cylinder problems or perhaps a burned valve. But this evening after mowing (incredibly poorly and slowly) I got fed up and pulled the plugs. Neither side shows evidence of oil burning (if anything they look a tad lean) and the right side (passengers side) was wet. It wasn't oil so I assume it's gas, but I have no sense of smell so I really couldn't tell. I then did a compression test and I have 180psi at both sides. This tells me the motor isn't blown, I believe. So, I am now contemplating some arcane situation where I am actually flooding the engine due to a carb issue, and this is making it bog down and also making the right side plug wet. But, I am not aware of a scenario where the motor gaining rpm's after a flooding situation would make it smoke gray/blue. Black sure, but not blue. So, that's where I'm at.

Any advice on this would be GREATLY appreciated. Having a 100-hour-old $5000 mower that doesn't work is gnawing at my soul...

Thanks to all,

AC
Click to expand...

Have you checked the valve adjustment? Maybe even a push rod is off and you are only running on one cylinder. I would check the wet one side for the problem.
 
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