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Mower Timing Problem ?


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08-01-04, 06:57 AM   #1  
6acreplus
Mower Timing Problem ?

Newbie here, first post. Have Craftsman riding mower with 15 HP Kohler engine owned for about 10 years. Now hard to start, developed gas leak on carb, replaced carb. Starts better but frequently backfires on starting and seems to have less power. Wonder if timing is the problem? Any suggestions appreciated, including how to check / set timing. Thanks. Roland

 
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08-01-04, 07:40 PM   #2  
Hello Roland!

Have you replaced the spark plug? There are no timing adjustments on your engine. A bad plug will cause the problems you described. If this is an OHV kohler command, it will use a champion RC12YC plug.


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08-03-04, 03:41 AM   #3  
6acreplus
6acreplus

Thanks, Replaced 3 year old plug per your suggestion, runs better but still backfires on starting. Backfiring just started this year, mower Craftsman Kohler OHV Command 15 HP about 10 years old. New carb but backfired with old leaking carb also. Any other thoughts? Thanks, Roland

 
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08-03-04, 03:06 PM   #4  
Without having the ability to hear the machine at start up, I'm wondering if you have a cough rather than a backfire. Check to be sure you are getting full choke. To do such you will need to remove the air filter and look at the "butterfly" valve and move the choke control to full and observe the position of the valve, making sure it is fully closing off the opening of the carb. Another possibility is old or just trashy fuel. Let us know about the choke position first then, if needed, we'll continue on.

 
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08-10-04, 07:53 AM   #5  
6acreplus
Thanks - Still Plugging Away at Problem

Definitely a backfire! Flame visible out carb when air filter is removed. Checked choke and butterfly appears closed fully. All fuel is new. Yesterday the engine died after running about one hour and wouldn't immediately restart. May not be related to backfire problem. Appreciate suggestions.

Roland

 
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08-10-04, 10:53 AM   #6  
Azis
just a fleeting thought, but I have had similar problems, usually on shutdown however, the seat safety switch if briefly opened, (usually by the operator moving or lifting slightly,or in my case not enuff lead in me back pockets ) can cause backfire. Actually I think the solenoid on John Deeres is to prevent this.
May not apply here but easy and quick check.

 
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08-10-04, 02:44 PM   #7  
It certainly sounds like an ignition related problem. Using a reliable in-line tester, check for spark. Bear in mind that a defective safety switch could be at fault. A process-of-elimination-check will need to be performed to determine such. Post back with the results of the in-line test first though.

 
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08-16-04, 05:12 AM   #8  
6acreplus
I'm not familiar with mower ignitions but have set timing on cars. The spark on this mower is not like a car, i.e., a steady, consistent zap. It seems to be many sparks, "zaps" very close together IMO too close to allow piston travel, but again I am not familiar with what to expect.

On last attempt to start it didn't backfire until about the third attempt and then kept up backfiring for next three attempts.

I have limited equipment, is there some inexpensive thing (guage, light, etc) that may help identify problem? Thanks for help. Roland

 
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08-16-04, 07:58 PM   #9  
6acreplus
Do you think that possibly the intake valve could be sticking open and when the combustion hits, the gap that is open allows the flame to shoot out the carb. Also if it is slightly open, it would affect the compression causing hard starting and rough running.
Just my 2 cents.

snoman

 
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08-16-04, 09:06 PM   #10  
Good thought snoman! That's a very good possibility. Check compression. You might well have a valve stuck open.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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