Where is my air mixture screw???

[vaultf600]

My bike is haveing a real hard time starting unless its completely warm. I have read some posts that say this is symptoms of the air screw being gummed up and not adjusted. I have a 81 750 i belive and it has the same vacum operated carbs as this site shows for the cleaning instructions....everything looks exactly the same but i just have caps over the spot where it looks like my air screw goes whats up with this...any help would be great thanks.
Ian

[Boondocks]

The carburetors were adjusted to EPA emission regulations at the factory. The pilot screws were sealed with covers to prevent adjustment. The engines tend to run lean at idle and moderate throttle settings due to the EPA pilot screw setting. The covers can be removed and the pilot screws adjusted for better results.

Use the search for "pilot air screw" or variations. There are threads out there that will tell you how to remove the covers and adjust the screws. When adjusting the screws, be careful not to put pressure on the tip when screwing it in to begin the adjustment. Pressure can damage or break the screw tip, causing a lot of grief.

[wiredgeorge]

The caps over your air mix screws are glued in place. The easiest way to remove them is to drill a small hole (about 1/8") and use a nail or screw, inserted into the hole, to pry the cap out. Don't drill too deeply or you will damage the head of the mixture screw. The air mixture screws are not all likely to be damaged if seating them as they are blunt unlike the pilot fuel mixture screws on the front/float bowl. The pilot FUEL MIXTURE SCREWS are sharply pointed and if seated too hard, the tips can easily break off.

[vaultf600]

thanks fellas !!! i was wondering if that was the case but didn't want to do it until i knew they could come out. thanks again for the help

[cfcubed]

Just popped the caps on my carbs...

As above, used the search to find the great info here. Followed the advice:
1) grabbed the smallest sheet metal screw I had,
2) knowing the screw is just below the alum plug, used low-speed on drill (.1" bit) & *slowly* drilled hole. I was able to stop drilling just *before* the bit went clear through the plug. My plugs were almost 3/16" thick.
3) threaded screw into drilled hole, used a vice grip on screw & pulled plug.
After this, sprayed carb cleaner on the screw heads to attack the glue that was holding them in place, then they turn no problem.
I'll probably replace the plugs after adjustment because here in NJ we have m/c inspection & don't want to risk fines, etc.

[Jethro]

When I had a problem like this it ended up being the starter jet and the fuel feed port in the float bowl itself.

Take off the float bowls and you'll notice a small brass tube about an inch long that goes into it's own cavity in the back of the float bowl housing. That is your starter jet. Take a piece of 10 gauge wire and pull a single strand of the copper wire out. Use this with some carb spray to make sure all the tiny holes are free, especially the bottom hole.

In the float bowl housing itself, this brass tube is fed by a tiny port in the bottom of the float bowl. Since it is in the bottom of the float bowl it is common for it to be plugged with grit or gum from the gas. Take the carb spray and wire and make sure this tiny port is free and flowing.

I think you'll find that the mix screws are likely not the problem, but I might be wrong. I'll tell you, I wish I never took the caps off mine, now I adjust them every time I have a problem!

[KEITH KRAUSE]

If the caps are still on and it looks like they've never been tampered with, then they shouldn't need adjustment.
It may help to remove them, counting as you turn, and clean/blow the passage out.

[rckrzy1]

the tips of those screws will break off easily if you bottom them out hard, it's why I got my bike for cheap as the PO broke of #1 and #2 so neither cylinder ran at idle, so gently bottom them out. Unless you like the joy of getting the broken needle tips out.

[vaultf600]

thanks again guys i got it starting much better and easier now two of the air screws were plugged up to start with so i took them all apart and cleaned them out. this is my first street bike but it still doesn't feel like its gettin enough gas at about 4k rpms. tomo i'm going to unhook my carb vent that i just read about. I had also put on a filter which i took off now and didn't seem to fix much. petcock has been rebuilt. carbs are all clean and boots look good too. i started at 1 and 1/2 turns out but now i think i'm more like 2 and its running a bit better. i do have a 4-1, pods and i think 180 and 115 jets but i'm not sure whats stock in it either. any other sugestions and does two turns out seem right. ??? thanks to all

[KEITH KRAUSE]

Check out your stock jet sizes and let us know. Good chance you're lean. How are the plugs at different throttle positions?
Carbs may need a good cleaning/vacuum synch and possible rebuild of some o-rings.