79 et300 runs good for ten minutes then dies unless you choke it

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kylemorgan88

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Joined
Feb 19, 2013
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3
Age
36
Location
minocqua
79 yamaha enticer 300 fires up from cold on 3 pulls every time and will run good for about ten minutes and then if you let it get anywhere near an idle it will bog out and die. You can keep it running if you go to half choke before it dies. Went through the carbs and made all the proper adjustments or what I thought was right. Any help would be greatly appreciated. Thanks in advance!!
 

Too many possibilities. I would try to identify what is missing (air/fuel, compression, ignition) at the time it runs poorly. Once you determine what is missing then your list gets a lot shorter.

Things I would attempt to check when it runs poorly . . .

  1. Compression
  2. Intake boot or Crank seal leaks - use carb cleaner or starting fluid
  3. Spark
Sometimes the crankcase pulse that is used to pump fuel gets weak due to low crankcase pressure or failing hose.
Heat from the engine bay is likely causing a component to quit working properly.
 
I wonder if the low speed windings may be failing. the windings may get warm and expand, losing contact. another possibility. when it does die do you have to let it cool down before it will restart?
 
Possible ignition breakdown as sled heats up (coils). Real PITA to detect. I went through this myself. Checked all coils resistive values. EVERYTHING clean and "minty fresh" on the fuel side. Middle of summer, started it up and let it idle for 30 minutes without a hick-up. Fog, remove fuel, stored for summer, winter arrives, fresh gas...etc,etc... ride for 10 minutes and dead. Changed stator plate and Voila..!
 
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