Need help with Walbro carb. It's on a "28n700" B&S 15.5 HP. 1999

sillyboy

sillyboy

Active Member
Hello All, At the end of last summer I had a mower shop trouble shoot a non-starting engine. It was fixed, but the exhaust smells like it is running rich. Did not smell that way when it was running during the summer (2022).

Does anyone have a diagram (picture), and instructions on how to set up the carb?
I would sent a picture but the mower is still in my shed.

Thank You...
sb
 
Hi smalltimer, thanks for the reply.
The exhaust odor I smelled (rich), the gas was only 2 weeks older than from when it was running good, with no odor.
I have been storing my mower in the fall, in my shed, since 2009. I put Stabol in the gas every year before storage.
Starts right up in the spring. Battery also removed and kept in my garage on trickle charge.

I just need instructions to set up the carb. ;)

Thanks sb
 
There is only two adjustments that the user can perform.

  • Idle mixture. Set at best speed between too rich and too lean.
  • And idle speed which is usually set at 1750 rpms.
 
Hello...On the idle-mixture screw what is the starting point? OR, how many turns out from fully closed? There are lots of conflicting answers to this question online.
Plug was never changed from the shop.

Thanks
 
As a rule of thumb I use 1-1/2 turns from seated position. Note on some carburetors these mixture screws have no effect especially on the idle jetted Nikki carbs; unless, the jet is resized.
 
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