# B&S Model 281707 Carburator Adjustment



## smata67 (Nov 29, 2005)

I have the O and M manual for the I/C Model Series 281700 that supposedly covers this engine. On Page 6 of the manual is the adjustment procedure for the carburator. Problem is that mine appears to be somewhat different to the sketch shown, it looks almost exactly like the carburator on the left, except that mine does not appear to have an idle speed adjustment screw. I've fiddled with it enough that I've got it running ok, but it always pops on turn off and at the lowest throttle position, the unit keeps running. I do have an rpm gage and am prepared to do it right, but unfortunately, need a bit of walk through on this one. If someone can identify the model of this carb maybe I can find a step by step procedure for it, the one in the manual is just not working for me.


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## hd4ou (Aug 25, 2009)

looks to me like the top screw is low speed adjustment. middle screw is idle speed, and bottom screw is high speed adjustment. procedure is about all the same. Get her running, back the screw out till it just starts to idle rough and mark that spot then turn it in till it clears up and keep goin till it start to just idle rough again and mark that spot and the back it out to middle of the 2 spots you marked. same for high speed adjustment. If this isn't working for you then it may need a cleaning and/or a rebuild. 

by the way that is called a large 1 piece flo jet carb. can be found on page 49 of the briggs L-Head manual part#270962-12/03


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## smata67 (Nov 29, 2005)

This is the procedure from the manual. It looks to me that the middle screw is to adjust the stop not idle speed or is that the same thing? Does the throttle control lever need to be on "SLOW" or is counterclockwise rotating the throttle as described in the procedure good enough? Can someone offer additional clarification to this procedure? The last sentence says to adjust to a slightly rich mixture if acceleration is not smooth after going through the procedure. How is this done?


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## hd4ou (Aug 25, 2009)

The throttle stop I think on this one is just a tab that the idle speed screw hits to keep the engine at a certain RPM. rotating the throttle counterclockwise just puts the idle speed screw firmly on the stop so proper RPM adjustment can be made without the throttle cable interfering with it. To richen it just unscrew the high speed adjustment screw a bit.


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## smata67 (Nov 29, 2005)

My turn off procedure is to drop the throttle to its lowest position and turn off the key. I ocassionally get a backfire. Do I need to go leaner or richer?


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## 30yearTech (Sep 14, 2006)

What your actually getting on shut down is an after fire. This is when unburned fuel collects in the muffler and it's hot enough to ignite this fuel. Try letting the engine idle for about a minute after running at high speed before shutting off. This will allow the temperature in the muffler to drop and may eliminate the after fire.


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## smata67 (Nov 29, 2005)

I think I might need to rebuild this carburator. It is 20 years old now. Engine (280707) does not run smoothly, a momentary drop in rpm every so often, and it continues to backfire on turn off (I am dropping the throttle prior to turning the engine off). What parts should I be looking at replacing? I'm thinking about a wholesale rebuild to keep me going another 20.


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## smata67 (Nov 29, 2005)

Apparently I need a 394698 kit. I search ebay and found all of these listed:

http://shop.ebay.com/i.html?_nkw=39...3286.m270.l1313&_odkw=520164&_osacat=0&bkBtn=

Are all B&S, or are there aftermarket parts? Any reason why I should stick with B&S if in fact, there are 3rd party sources?

Also, jacks small engines says P/N 520164 replaces 394698. No one else seems to be selling this replacement P/N. Is it possible that the newer kit is a better performer, perhaps better with ethanol?


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## indypower (Apr 8, 2009)

The 394698 is the Briggs part number. For carb parts, I use *ONLY* OEM parts as I have found they work & fit so much better. The ones you showed on Ebay are aftermarket kits. The OEM kit is within $2 of the aftermarket kits. Go to your local small engine shop and get the OEM Briggs kit.


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