I’m still having a fast idle when engine is fully warmed up on my 12 year old 26hp V-twin B&S. The hotter the engine…..the faster the idle until it reaches about one third to half the throttle range. I’m figuring an intake leak, but all my attempts to locate it proves nothing. I’ve tried s50 weight oil on the entire outside of the intake and no change. I’ve tried using propane gas from my unlit torch all around the intake and carburetor areas and still no change. The throttle linkage and all related brackets and connections have been checked to ensure complete closure. Any ideas or suggestions?
Still having fast idle when engine is warmed up. Cold idle is normal.
- Thread starter bodean
- Start date
bertsmobile1
Lawn Royalty
Idle or no load speed.
Your engine is supposed to idle at its full running speed
You can slow it down to around 1/2 the full speed by moving the throttle lever to the slow ( Turtle ) position .
Why are you trying to make an engine that wants to spin at 3400 rpm run at a slower speed ?
Your engine is supposed to idle at its full running speed
You can slow it down to around 1/2 the full speed by moving the throttle lever to the slow ( Turtle ) position .
Why are you trying to make an engine that wants to spin at 3400 rpm run at a slower speed ?
Because the idle was considerably lower when it was new. It’s 12 years old now(350 hours ) and the idle is at least 3 times faster than the 5 year old model which still idles normal. It idles normal RPM until the engine reaches full operating temperature. and then when the outside temps get into the 80° to 90°F range, I can almost mow tall grass at idle.
StarTech
Lawn Royalty
What the OP is referring to is the engine's idle speed (turtle mode as you call it). These engines usually idle at a governed idle speed of 1750 rpms with a dead flat idle speed of 1200 rpms (throttle against the idle stop screw). When the dead flat idle is set incorrectly due to either messing the idle speed stop screw it can cause this and usually they will settle back down to the 1750 but it can take a while. Many operators and techs mistakenly adjust the idle speed stop to the 1750 rpm which is wrong for the governed idle setup.
This adjustment does take a RPM meter to set it, you can't just guess at it. I know I had several engines here that would do similar things and took me following the SM instructions to stop them from this. For some reason these can get in a self feedback loop and don't want to return to governed idle speed right away. This very to the problems we can have with the old updraft carburetors and they too had to be tuned a particular way for them to operate right. I know reading and following the SM instructions are a pain for us know it all types. It took me a year to learn to set this adjustment as I just over looking it in the service manual.
Now if once you perform this adjustment and the engine still does this then I would for worn carburetor parts like the throttle shaft, linkages, or some other item. But you got to start with the basics first and troubleshoot from there.
This adjustment does take a RPM meter to set it, you can't just guess at it. I know I had several engines here that would do similar things and took me following the SM instructions to stop them from this. For some reason these can get in a self feedback loop and don't want to return to governed idle speed right away. This very to the problems we can have with the old updraft carburetors and they too had to be tuned a particular way for them to operate right. I know reading and following the SM instructions are a pain for us know it all types. It took me a year to learn to set this adjustment as I just over looking it in the service manual.
Now if once you perform this adjustment and the engine still does this then I would for worn carburetor parts like the throttle shaft, linkages, or some other item. But you got to start with the basics first and troubleshoot from there.
bertsmobile1
Lawn Royalty
At minimum idle speed the engine is just barely getting enough air flow to keep a new CLEAN engine within the operational temperature .
They are not car or motorcycle engines and are not suppose to be run at any speed other than full throttle.
My guess is you are running the engine two slow so it is overheating thus running fast .
Apart from bleeding the hydros there is no other time that the engine should be run at any speed but full throttle.
They are not car or motorcycle engines and are not suppose to be run at any speed other than full throttle.
My guess is you are running the engine two slow so it is overheating thus running fast .
Apart from bleeding the hydros there is no other time that the engine should be run at any speed but full throttle.
I just realized that I failed to mention in my title that cold idle is normal.
Bodean my 37 hp. Briggs and Stratton does this also. When cold and newly starting it the idle speed is ok. But after mowing awhile and returning to park it the idle speed is a great bit higher than what I like. Someone who is more knowledgeable here please explain and respond how to remedy this. I forgot to add, this is a twin cylinder motor on my 2013 Scag zero turn.
That’s exactly what mine is doing