Idle air screws missing?

[Hishman]

Hello everyone.I recently purchased my 81xs400g. When i got it is spittered an spattered at low rpm unless the choke was on. I cleaned the carb with spray and noticed one jet was totally blocked. Happy to see this i figured it would solve the problem. Put my carbs back on only to have gas fill my entire intake. Taped on the float bowls and that freed them up so solved the overflow problem. Problem is my bike still wont idle off of choke and sputters at low rpm when i try and turn down the choke. Still it runs excellent at higher rpms. But iv'e also never ridden a motorcycle so i wouldn't know if it is running perfect. Anyway iv'e read the idle air screws are super lean from factory so i was gana richen the idle air screws. Only problem is there arnt any! So what up with the little caps? I tried getting them off with a pic with no luck.

 

[Scorpio1963]

Those caps cover your main fuel jets.You might have use a small screw driver or pointed object to be able to rove them.Its a good thing that they are tight.Your idle screw are on the left side of the venturi.Dont try to remove them,they will only get mangled..If they are plugged use a small fine wire to probe them.

 

[Hishman]

Wait im confused. The cap im showing youis not where the the idle/pilot screw is supposed to be? I'm referring to the cap that has a small hole in the center of it located directly in the center of the picture.

 

[Scorpio1963]

Ok sorry different year carb than what I was thinking.Thats the idle screw.It also functions as an adjustment to the how far the butterflyies open.There should be another screw on the bottom which can be adjusted.Just dont play with them too much cause you will get your carbs way out of balance

 

[Hishman]

Thats what i thought the only problem is there is no screw there? That was my question. It doesn't look the the plastic cap iv'e read about. It also doesnt look like the needle was broken off.

 

[Scorpio1963]

That is strange cause my bike is an 81sh I wouldnt think there wouldnt be much difference on the carbs unless someone has put a different one on.Also look up the manual and diagram for your carb here on the site or partszilla.It will give you a complete breakdown on the carbs

 

[Scorpio1963]

Is there 2 of the brass caps one on each carb?If so its the air /fuel mix screw.They are capped from the factory.Antitamper/emmisions function.

 

[Hishman]

Yes they are both capped. Is there a method of removal?

 

[Scorpio1963]

If theres a hole already in them take a small point object and pry them out.If not use a drill be very carefull and drill a hole in them.Or take use a big nail and punch hole which is probaly the best bet.

 

[drewpy]

lightly thread in a self tapper and lever it off

 

[HoughMade]

Let's get some things clear.

1. In the first post, that a cap over the idle mixture screw (NOT idle air screw). Get that cap off, and there is an adjustment screw underneath. Be careful that you do not mess the screw up.

2. The screw adjust the amount of fuel in the idle circuit, not the amount of air. In is leaner, out is richer.

3. That screw has nothing to do with the throttle butterflies. The idle speed is adjusted by setting how far open the throttle butterflies are at idle. the idle air screw is between the carbs and adjusts both at the same time.

4. If the carbs are clean, set both idle mixture screws the same. Then, adjust the balance with a manometer using the screw on the shaft between the carbs. Last step, set the idle speed with the idle air screw.

 

[Scorpio1963]

Its been cleared up already.