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Old 10-27-2011, 10:22 PM
Central Island Lawn Central Island Lawn is offline
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Briggs motor woes

Hi all
I picked up a very inexpensive Snapper Rider. It's small, 25" cutting deck, but it's a really fun machine and the smaller size is easy to get in to smaller spaces and it turns on a dime. It's an older unit and the 6 HP Tecumseh was a POS, and I can't get parts for it anymore, so I picked up a used 12 HP Briggs motor for about $200. I have this problem where the engine will start great when cold, run for about 30 to 60 seconds. Then the governor will take over and start adjusting the throttle, engine RPMs will drop and eventually the motor will cut out. The carburetor that was on there would leak fuel, even with a new carb kit, so I replaced the carb. I've also replaced the ignition coil, spark plug, and re-wired the starter. What I have not done is hook up the alternator to the battery, which shouldn't make a difference other than recharging the battery. I also have not replaced the air filter, which seems a little too obvious. I'm going to replace the air filter tomorrow, but I wonder if there is something else that I should consider. The engine does get hot fairly quickly and that is when it shuts off.


PS. The mower cost me $200, $200 for the engine, and $200 for a new carb.
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Old 10-27-2011, 10:55 PM
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Restrorob Restrorob is offline
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$200 for a carb ? Dayum !

Can you post the engine model and type numbers ?
Originally Posted by piston slapper View Post
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Old 10-28-2011, 02:19 AM
Central Island Lawn Central Island Lawn is offline
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The engine model and type is:
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Old 10-28-2011, 10:09 AM
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dutch1 dutch1 is online now
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What the code number--the last of the three engine numbers. The first two digits of the code will indicate the year of manufacture. Judging from the carb on that engine, it's likely an early to mid 90's engine or possibly earlier.

A used engine is most always a gamble unless you know it's history, observed it run or have done some elementary testing.

Unfortunately, the train has already left the station and you've got $400 wrapped up in an engine that isn't doing the job.

Where to start?

Check the compression, cold and hot. Low compression could mean several things--valve problems, cylinder/ring wear, head gasket leak

Adjust the governor properly.

Check for any possible intake leaks.

Don't spend any more money on it until you know it can be made satisfactory within the limit you can afford to invest. Internal engine work can get pricey unless you can perform the work yourself.

Just a few random and elementary thoughts. Rob/others will likely come back with some additional suggestions as well.

Good luck.
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Old 10-28-2011, 04:08 PM
Central Island Lawn Central Island Lawn is offline
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Something I would like to add:
I just ran it. It started great, first crank all the time without any choke on low throttle. I left it to run at idle, once it warmed up it was a little rough but kept running. It didn't die until I added throttle and let it run at full throttle for a few seconds. Running at lower throttle seems to be okay though.
What are the chances that it's the air filter?
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Old 10-28-2011, 09:23 PM
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piston slapper piston slapper is offline
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What does the sparkplug look like?
Clean or oily or black and sooty?
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Old 12-03-2011, 11:38 PM
jdunk jdunk is offline
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carb issue out of ajustment starts with out choaking running rich idel circuit?
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