Missing when at full throttle.

[LaWn GuY]

I adjusted the carb today and got It to Idle perfect and Idle on It's own, but when u full throttle It It sounds like It misses but It still runs great. I drove It around the block and It didn't stall once sounded great, I even engaged the blades and no power loss or hesitation. Also noticed when It's at full throttle the Idle screw/Idle valve bounces back and forth causing It to rev up and down, If I hold It sill It runs perfect. It's a 12 HP Briggs & Stratton Flat Head.

 

[mechanic mark]

Post all numbers from engine data plate, thanks. A quick fix may be blue loctite on idle screw threads, but it sounds like you may need a carburetor kit or new carburetor, worn out parts.

 

[shiftsuper175607]

I adjusted the carb today and got It to Idle perfect and Idle on It's own, but when u full throttle It It sounds like It misses but It still runs great. I drove It around the block and It didn't stall once sounded great, I even engaged the blades and no power loss or hesitation. Also noticed when It's at full throttle the Idle screw/Idle valve bounces back and forth causing It to rev up and down, If I hold It sill It runs perfect. It's a 12 HP Briggs & Stratton Flat Head.

Do you have an in-line spark tester?
Are your plug/s breaking down? Or a bad boot or connection at the spark plug...

 

[LaWn GuY]

Post all numbers from engine data plate, thanks. A quick fix may be blue loctite on idle screw threads, but it sounds like you may need a carburetor kit or new carburetor, worn out parts.

B&S Model Number 281707 Code 0412 Like I said earlier the Idle valve/governor bounces back and forth a little at full throttle causing It to run funny. But I can live with the, but when It's Idling It doesn't move It's still and runs perfect.

Do you have an in-line spark tester?
Are your plug/s breaking down? Or a bad boot or connection at the spark plug...

The boot looks fine, but Im gonna pull the plug and replace It anyway since I don't know when the last time It was replaced.

 

[Tinkerer200]

when It's at full throttle the Idle screw/Idle valve bounces back and forth causing It to rev up and down, If I hold It sill It runs perfect. It's a 12 HP Briggs & Stratton Flat Head.

Sounds to me like either the little spring that coils around the governor rod and runs the length of the governor rod is missing OR the throttle shaft is worn out where it goes thru the carb body, most likely. Replacement shaft less than $10.

Walt Conner