Carb rebuild questions

[Wombat_Scat]

So last year in about March, I picked up my GS850g. It was running but only on what seemed like 3 cylinders. I didn't ride it and made plans to work on it over winter to get it ready for the summer this year.

The previous owner said they had the carbs cleaned/rebuilt and still couldn't get the bike running right and i think I found out why today.I pulled apart all 4 carbs today and found a few concerning things.

First major issue was in carb 3, before pulling it apart i noticed the slide didnt operate like the other 3 carbs, it was stiff and wouldnt open all the way. As i was taking off the top cover i noticed the diaphragm slide spring was installed poorly and wasn't seated properly in the top cover. I took a picture as i was taking the top cover off.

The second issue was that the pilot screw O-ring was missing on one of the carbs, I couldn't see it left in the screw hole but i went fishing for it with a piece of wire anyway and couldnt find it. What kind off effect would this missing O ring have?

The last issue was that one of the diaphragms was installed poorly and was pinched under the top cover. there isnt any tears or holes in the diaphram but has 2 pinched edges so i think it will be fine to reinstall but wanted to see what people thought. Should i find a replacement?

I'm surprised the bike was able start and idle, you could even Rev it but it wasn't very smooth.

[Wombat_Scat]

Here's the slide spring picture.

[Wombat_Scat]

Heres the other side of the diaphragm.

[KiwiAlfa156]

Just reinstall the spring and seat the diaphragm correctly. Had the same pinched/folded diaphragm issue with one of my bikes when I got it (ran on three above idle) and have no issues since putting them together properly after a good cleaning. If it still misbehaves after correct reassembly, then replace it.

The missing o-ring on the mixture screw could have potentially leaned the mixture going past the pilot needle tip, which in turn could possibly have been tuned out by screwing the screw in richer.

The mixture passing thru the pilot circuit is set by fuel metered by the pilot jet and air metered thru the pilot air jet. The pilot circuit is the pilot orifice adjustable by the pilot screw and by-pass orifices which are non-adjustable and are progressively revealed to the airflow/vacuum by the throttle butterfly opening.