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disturbed emissions mixture screw (small jet with color painted seal)

  • Thread starter Thread starter TyeGuy
  • Start date Start date
T

TyeGuy

Guest
So upon some basic carb maintenance the other week on my 78' GS550, I noticed how filthy my carbs were (inside and out), so I decided that I would take this opportunity to disassemble my carbs and send them in to get vaporblasted. I had told the guy who I sent them to that I left the small colored paint seal jet (figure 37 in Clymers) in the carbs because my manual says not to disturb it. Which he said was fine.

I got it back yesterday and noticed that the painted seal was blasted off (figured it might happen), and now the jet is free to be set. However, my manual says "This jet is pre-set at the factory and cannot be recalibrated in the field. If disturbed, the carburetor adjustment can be severely affected."

I am wondering what is the proper adjustment for this small jet (emissions mixture screw), and do I need to find a sealant to seal it again like the factory setting?

Thanks,
Tye
 
Have you or someone actually disassembled these carbs and properly cleaned them? Either dipping or decent ultrasonic method?
 
That statement was required to keep the EPA from getting on the manufacturers as they new full well the carbs were gonna get fiddled with. What you do is make a witness mark o the side of the hole right in line with the slot. Slowly turn the screw in and count how many turns it takes to gently seat them..record the reading.

get a muffin tin and set all the parts from a carb in its own spot as you tear down the carbs. When reassembling see what each carbs screw was at and set them accordingly.
 
tom203 said:
Have you or someone actually disassembled these carbs and properly cleaned them? Either dipping or decent ultrasonic method?
Click to expand...

Yes, I've disassembled them completely and have cleaned them properly. Everything is ready to be reassembled. This underside factory set mixture screw is 1 1/4 turns out from closed. I just wanted to make sure its adjusted properly and if its fine to leave it without a sealant.

Everyone on the forum seems to only talk about the air/fuel mixture screw. I'm talking about the factory set mixture screw on the bottom of the VM22SS carbs.
 
chuck hahn said:
That statement was required to keep the EPA from getting on the manufacturers as they new full well the carbs were gonna get fiddled with. What you do is make a witness mark o the side of the hole right in line with the slot. Slowly turn the screw in and count how many turns it takes to gently seat them..record the reading.

get a muffin tin and set all the parts from a carb in its own spot as you tear down the carbs. When reassembling see what each carbs screw was at and set them accordingly.
Click to expand...

They were set at 1 1/4 out from closed. They had a colored painted seal before I got them vaporblasted, am I find with resetting them 1 1/4 out and without a sealant?

My carbs are completely broken down and parts separated per carb. Assembly should be pretty easy.
 
The sealant isn't an issue..its usually a paint pen they used to show if they were tampered with if a customer brought a bike in claiming they didn't mess with the carbs...yeah right !!!


If you counted 1 1/4 out and they all were there or very close to that then set them the same.
 
1-1/4 open on those pilot fuel screws is going to be quite rich unless the bike was modded.
 
If they were at 1 1/4 he should set them there.. especially if the factory markers were still there. Thy can be tweeked from that starting point if need be.
 
Nessism said:
1-1/4 open on those pilot fuel screws is going to be quite rich unless the bike was modded.
Click to expand...

Ed, The bike hasn't been modded, this post is for the "emissions" mixture screw at the bottom of the carb (that the float bowl cover slips around). This isn't the pilot air/fuel mixture screw on the side of the carb
 
TyeGuy said:
Ed, The bike hasn't been modded, this post is for the "emissions" mixture screw at the bottom of the carb (that the float bowl cover slips around). This isn't the pilot air/fuel mixture screw on the side of the carb
Click to expand...


You are using non standard terminology.

What you denote "pilot air/fuel mixture screw" is actually the pilot air screw.

The "emissions mixture screw" is the pilot fuel screw.

Typically the pilot fuel screw needs to be set at 3/4-1.0 turns open from lightly seated. The problem is that it's very hard to tell when the screw is "lightly seated." Most people over tighten the screw when trying to measure and often times they count too many turns and/or the tip of the screw gets jammed into the carb body and then the tip breaks off. I had a bone stock 550 that I spent a lot of time working on and my bike was running rich at 1.0 turns open. I had to back that off to about 3/4 or 7/8 of one turn before the bike ran right.

Typically, but not definitely, the pilot air screw (on the side of the carb) needs to be set at about double the pilot fuel screw. The factory manual suggests 2.0 turns open so I'd start there and tune as necessary.
 
Set your screws where they were when you counted. Readjust once its up and running. EVIDENTLY if they had marker lines across them..or seals from the day they were made its telling you they were tuned and thats where they were when it left Japan.
 
Nessism said:
You are using non standard terminology.

What you denote "pilot air/fuel mixture screw" is actually the pilot air screw.

The "emissions mixture screw" is the pilot fuel screw.

Typically the pilot fuel screw needs to be set at 3/4-1.0 turns open from lightly seated. The problem is that it's very hard to tell when the screw is "lightly seated." Most people over tighten the screw when trying to measure and often times they count too many turns and/or the tip of the screw gets jammed into the carb body and then the tip breaks off. I had a bone stock 550 that I spent a lot of time working on and my bike was running rich at 1.0 turns open. I had to back that off to about 3/4 or 7/8 of one turn before the bike ran right.

Typically, but not definitely, the pilot air screw (on the side of the carb) needs to be set at about double the pilot fuel screw. The factory manual suggests 2.0 turns open so I'd start there and tune as necessary.
Click to expand...

Appreciate you correcting me with the pilot screws. I admit this is my first time disassembling my VM22SS carbs, so I'm learning as I go. I was taking the "emissions mixture screw" term from cycleorings.com. Glad you cleared that up for me.
 
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