high rpm at idle

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  #1  
Old 05-06-06, 01:09 PM
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high rpm at idle

Have a John Deere push mower powered by a Briggs and Straton 6.5 hp engine with overhead valves. The mower is self propelled, but does not have a variable idle. My original problem was a no start scenario with a blown head gasket, but that has been solved. The mower starts ok, a little kick back at times on the starter rope, but then goes into a very high idle, and has alot of vibration to it. It has a float carb. Seems like too much gas is getting in. Is there a governer type thing on this engine? Thanks for the help...

Dan
 
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Old 05-06-06, 03:33 PM
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The problem with the high engine RPM's sounds like tention on the govenor spring,located near the throttle shaft,out of the carburetor.Replay back and give model and type #'s to engine because some of these has one spring and some has two.

The kick back of the pull rope is caused by ether a lose blade or a sheared flywheel key.Which is prob.what it's gona be since you said that "the mower has alot of vibration in it".Sounds like you or some one hit something and bent the blade or crankshaft.
This, most all of the time gets the flywheel key too.
 
  #3  
Old 05-06-06, 06:06 PM
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Thanks for the suggestions...The model # on the engine is Briggs & Stratton 121602. It is a 4 cycle 6.5 hp that is supposed to run in the 3000 to 3200 rpm range. Govenor spring eh? Well inbetween the carb and the head there is bolted a chrome flange that is L shaped and has a spring mounted to the top side of it. The spring goes to a metal rod that is connected to another metal rod somewhere at the back side of the engine, under the fuel tank. The thing I can't seem to figure out is since this engine is set to run at one speed how exactly that system of rods and spring do anything to regulate the speed of the engine. Thanks in advance for any insight.

Dan
 
  #4  
Old 05-07-06, 02:49 PM
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when runing,the engine is at full RPM's.The govenor spring pulls on the gov.for a more controlled speed.

But after thinking on your problem,I am sure that you will find a sheard flywheel key and replacing that key is gona fix everything.The key puts everything in proper time with each other (piston,valves with ignition) so when the timing is off............
 
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