Briggs 17.5 HP with Nikki Carburetor Surging only when cold . (Craftsman Lt1500)

[mstar]

I did not take the carb apart yet.
I wanted to see if there was anything else it could be as more than a few with surging said carb was not the issue.

My local repair shop said they normally don't need to take the Welsh plug out when they clean. But maybe that is because the put in a dip basket?

 

[Fragger]

Seafoam in the gas tank , it always seems to help my gasaholic engines . especially in my two stroke engines, walmart has best prices.:laughing:

 

[Ronno6]

I had a Honda carb that refused to be cleaned until I dunked it in the ultrasonic tank for a few cycles.

 

[mstar]

Do I have to remove the welsch plug? He repair place I bought the parts said no.
Do I have to remove the needle adjustment with the plastic cap? If so how do you"pry" it off and not break it? How do you ensure you get it back to the place it was if unscrewing it.

Are either of those two spots what could cause the cold surging?

 

[mstar]

Update: I did the carb cleaning. The interior was very clean, Everything looked good, My O ring was not deformed , my float needle looked decent but I still replaced it, the O ring and the bowl gasket and the paper gasket.

I am not sure if it fixed anything yet. It started a little rough but then smoothed out. Maybe it was quicker than before but there was a surge if I took it off choke right away and if I pushed it back into choke it could not stay there for long. I had to drop it back down bu then there was a little surge. It seemed not to take as long but I will have to try again.

I did "pry " off the the cap on the fuel mixture screw. Now I know how it is put on. for those who don't know it is a pressure fit over a ribbed end. Just pull it off with pliers with a little wiggle.

OK so what is the recommend procedure to adjust the carburetor. The fuel mixture needle I read you turn to just off, turn to 1.5 turns as a start point.
I had marked the spot before removing It was only 1 1/8 turns.

So I don't know how one knows if it is correct. Do I set when engine is hot? Where should the throttle be when set?

Do I touch the idle screw? What do you look for if you set that first. Again, the idea is to properly tune to stop the cold start surging.
Also should I have set the choke?

Thanks