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Hello - I have a Briggs 27 (13 0417 YG 23649) on a Simplicity Prestige (2691130-00) and when I start the engine it idles about 1700 rpm. After mowing, the idle will not go below 2100 rpm. Is there an adjustment for this?

It could be a case where the plastic intake manifold is heat warping causing an air intake leak which will effect idle rpm.

ILENGINE said:

It could be a case where the plastic intake manifold is heat warping causing an air intake leak which will effect idle rpm.

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Thank you, ILENGINE. Is the warping of the plastic intake manifold a symptom of something else? How difficult is it to replace? Thank you!

The plastic intake manifold issue is something that pops up at random on random engines. Most of the time it shows up as a rough run, loss of power issue. Most of the time is effects only one cylinder. The issue can result at either head when the O ring flattens out over time, and in some cases the flange will warp. Most of the time the issue is at the carb mounting flange where if the carb mounting bolts are overtorqued will cause the intake to banana slightly at the carb mounting face.

bk10s said:

Hello - I have a Briggs 27 (13 0417 YG 23649) on a Simplicity Prestige (2691130-00) and when I start the engine it idles about 1700 rpm. After mowing, the idle will not go below 2100 rpm. Is there an adjustment for this?

Click to expand...

Remove the air cleaner and check to make sure all of the linkage moves freely. Age, grass chaff and a little rust will stiffen carburetor and carburetor linkage from moving freely.

49M877-5111-G5 with governed idle. This is a 2013 engine so someone may have monkey the carburetor settings.

Yes intake manifold do warp but first make sure the idle speed is set correctly. This engine base idle is set at 1200 rpm which is not the governed idle speed of 1750. I see lot of the time techs just adjust the idle speed for 1750 not knowing this will cause problems after the engine is warmed. The problem is the governor cant lower the idle as the screw let it close the throttle vane below initial setting if they use the screw and set at 1750. Also make the correct governed idle spring is the correct one with no color (based on the date posted)

This base idle speed got to be done by holding the throttle against the idle speed screw then setting it.

Service manual instructions.