what does running lean mean

J

jamesboater

Seaman Apprentice
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Mar 11, 2005
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hi i have a evinrude 25hp 1979 and iv been told its running lean what does that mean thank you
 
X

Xcusme

Commander
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Apr 21, 2003
Messages
2,888
Re: what does running lean mean

When a motor is running lean, it means that the fuel to air ratio is wrong. A lean mixture has less fuel and too much air in the mixture.Motors that have two mixture needle valves, one for idle mixture and another for high speed operation , need to be adjusted seperately. A lean running motor will run hotter and can cause piston damage among other bad stuff. When the mixtures are set to too rich, the motor will run sluggish and foul the plugs.
 
J

jamesboater

Seaman Apprentice
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Mar 11, 2005
Messages
43
Re: what does running lean mean

thank you my engine is back fireing it sort of kicks to one side trys to stall and lets out o puff off smoke would running lean cause this thank you for your help
 
R

rodbolt

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Sep 1, 2003
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20,066
Re: what does running lean mean

yes it will. <br />in the old automotive car engines it will shoot a flame out of the carb. however in your two stroke when the lean mix ignites while the piston is coming down compressing the air/fuel in the crankcase it will ignite and since the reeds wont let the gas out it will try to shove the piston back up. its called a lean sneeze. can shear flywheel keys and break reeds and generally do nasty things as well as blow out fuel pump diaphrams. the piston does not like explosions on both sides and it has a tendancy to remove/burn all the lubrication from the shiny parts thus leading to bearing failures.<br /> any other questions ?
 
U

umblecumbuz

Lieutenant Junior Grade
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Sep 25, 2004
Messages
1,062
Re: what does running lean mean

I've been running lean for years then, Rodbolt.<br /><br />I sneeze a lot and do nasty things, and now I'm getting bearing failure. My wife says flames sometimes shoot out of my carb also, and the old diaphragm's not what it was.<br /><br />Course - he could mean being low on bucks - that's kinda running lean.
 
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