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Old 03-20-2013, 09:08 AM
MowerMinister MowerMinister is offline
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weak spark on Kawasaki 18hp

I've got a Kawasaki FS541V AS07 R. A few weeks ago, the engine was constantly surging at high RPMs. I discovered that the muffler was cracked on both sides so after a small welding job we were back in action. Now its surging at low RPMs and a closer look revealed that I'm only running on one cylinder. I checked for spark on the the weak cylinder and had no spark. I removed the coil and cleaned the rust off of it and the magneto as well. I replaced it and put it back to the factory gap specs with a feeler guage. I have spark now but its very weak. I've rechecked the gap and everything. Does this mean that I have a bad coil? The other cylinder has great spark and the engine runs fine on that one cylinder its just weak when the blades are engaged. I'm assuming I have a bad coil but in the interest of saving my company money I wanted to make sure that there isn't anything else I should check before I start buying parts to resolve the issue.
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Old 03-20-2013, 12:29 PM
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Restrorob Restrorob is offline
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Swap coils side to side, If the other cylinder stops running buy a new coil.....
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Old 03-20-2013, 03:43 PM
MowerMinister MowerMinister is offline
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swapping coils only cured part of the issue. I'm still running on one cylinder even with a new coil installed because the old one ohmed out. Could it be a carburetor issue or maybe a valve problem on that cylinder?
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Old 03-20-2013, 05:20 PM
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Valk Valk is offline
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New spark plug with proper gap? Just sayin'...
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Old 03-20-2013, 06:15 PM
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Landrus2 Landrus2 is offline
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unplug the white wire from the coil (this wire kills your spark via ignition swith or safety switch
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Old 03-20-2013, 06:32 PM
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piston slapper piston slapper is offline
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Quote:
Originally Posted by Landrus2 View Post
unplug the white wire from the coil (this wire kills your spark via ignition swith or safety switch
Wouldn't an intermittent ground kill both the coils at the same time..??
Man...that avatar looks familiar..????
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Old 03-20-2013, 06:38 PM
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Landrus2 Landrus2 is offline
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Quote:
Originally Posted by piston slapper View Post
Wouldn't an intermittent ground kill both the coils at the same time..??
Man...that avatar looks familiar..????
Sorry I have orders to ignore you so no comment
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Old 03-20-2013, 08:06 PM
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Restrorob Restrorob is offline
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Not likely the carb being a single barrel feeding both cylinders, Possible intake gasket leak. Check by spraying carb & choke cleaner around the intake while running, Other thing is valve issues. Check the valves/adjustment, Should be 0.0039~0.0059" at TDC compression stroke....




Yeah Slapper...... Ole Joe didn't do a very good job at starting over with a new user name.....
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Old 03-20-2013, 09:01 PM
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BigFish BigFish is offline
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Have you pulled the plugs? What did they look like? Are you checking spark with a spark checker ? Should be able to jump a 1/4" gap.

With Kaw., the coils have an internal diode, so to accurately check them you have to pull the kill wire off both coils.

Per KAWASAKI :" No spark, one side - V-Twin"

" Isolate ignition coils. Connect gap style spark testers to the coils, grounding the testers to the engine. Unplug the shutoff wire from each coil. If the coil that had no spark still does not spark, replace it, this is the most common reason for no spark on one side. However, if spark returns to the coil that had no spark, the opposite coils internal diode has failed. The diode failure causes no spark at the opposite coil." ( when the harness is hooked up)
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Old 03-21-2013, 07:18 AM
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piston slapper piston slapper is offline
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Quote:
Originally Posted by BigFish View Post
Have you pulled the plugs? What did they look like? Are you checking spark with a spark checker ? Should be able to jump a 1/4" gap.

With Kaw., the coils have an internal diode, so to accurately check them you have to pull the kill wire off both coils.

Per KAWASAKI :" No spark, one side - V-Twin"

" Isolate ignition coils. Connect gap style spark testers to the coils, grounding the testers to the engine. Unplug the shutoff wire from each coil. If the coil that had no spark still does not spark, replace it, this is the most common reason for no spark on one side. However, if spark returns to the coil that had no spark, the opposite coils internal diode has failed. The diode failure causes no spark at the opposite coil." ( when the harness is hooked up)
Good info Fish...
Just wondering...if you installed a diode between the coils...like Briggs did on the old Vanguard twins...
Would that work around the problem..?? Or does the diode failure weaken the coil.??
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