Briggs 650 series running rough

[128mpr]

Why is my lawn mower running rough ?

It's a Briggs & Stratton 650 I/C series engine, 190cc.

I've posted a YouTube video here : https://youtu.be/2ZSbo5Ihai0

In the video it's running at full throttle but isn't developing power and is running rough.
I have found that by pulling on a small spring it will run much better.
I'm not sure if this is a choke or throttle control.

The assembly that moves that the spring is attached to looks like it might be bent a bit, but it doesn't appear to be enough to cause this problem.

Any suggestions would be most welcome.

Thank you

 

[pugaltitude]

I would start with cleaning the carb.
Maybe replace the carb oring which is on the back of the carb and maybe the gasket which is on the frint of the carb.
Loads of videos youtube which will show you how to do it.
Try a local dealer for a carb kit.
Take your model, type and code off of engine.

 

[bertsmobile1]

Mower theory 101.
The throttle cable you pull & push, pulls the throttle on the carb open and sets the maximum amount it can open.
The govenor closes the carb down to the amount it needs to be open.
The two work against each other so are connected by the spring that you are moving.

However your mower is missing something awefull, but doing it in a regular rhythem which suggests either an over rich mixture or a retarded spark
Rich is very hard to achieve with that particular carb unless the return hole is blocked or main jet has fallen out, both very rare occurances.
Retarded can happen if the space between the magnets & the pick up coil is too large, the magnets in the flywheel have lost magnetism or most common the key that keeps the flywheel in the correct place has sheared & the flywheel has moved on the shaft.

And please please if you are going to d a video like that, put the camera on some sort of a stand, even a stick knocked into the ground, a fence post or letterbox, anything to keep it steady.
Salvidore Dahli would have killed to get a fluid solid effect, but it makes it difficult to see what is actually happening