# Briggs and Stratton 3.5 hp, Idle Mixture Screw Question



## khowe9 (May 22, 2010)

Hello all,

Yesterday, I rebuilt the carb. on my 3.5 hp B&S lawnmower. I put together the idle mixture screw assembly, and put it in where it was supposed to go (there is a flat head design on the bottom, but it is not a screw just part of the mold). However, the screw assembly doesnt thread into anything, which seems very odd. I was able to just pull it stragiht out. 

I'm fairly sure this isnt correct; however, the new idle screw assembly looks identical to the old one. The old one was just that, old, so it didnt come out that easy but I dont think it was threaded in either.

I have pictures trying to show what I'm talking about. I guess my question is, is this correct? I'm having trouble with the lawn mower cutting out on me after 15 or so seconds when I'm mowing with it...

http://img295.imageshack.us/i/miniimg6393.jpg/

http://img404.imageshack.us/i/miniimg6400.jpg/


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## 30yearTech (Sep 14, 2006)

They just press in. the rubber washer on the end and the O-Ring help to hold them in. They do not screw in, in fact they cannot rotate due to the flat side. When properly installed they stay in place just fine and will not fall out.


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## khowe9 (May 22, 2010)

30yearTech said:


> They just press in. the rubber washer on the end and the O-Ring help to hold them in. They do not screw in, in fact they cannot rotate due to the flat side. When properly installed they stay in place just fine and will not fall out.



Thanks for the advice. I got it running and was able to mow the whole lawn with it, but I still had this lingering feeling that the mixture screw assembly was in wrong. Thanks for clarifying it, now I can breath easier knowing the jobs done.


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