Some newbie questions

Ok, so I'm inexperienced when it comes to bike fiddling so I really shouldn't have but... I recently got an 81 550, it has pod filters and was seeming to miss at low revs. I had the carbs balanced and this seemed to help a bit but not much. It was suggested to me to try the mix screws, I presumed it was the 3 that are on the far side of the carbs (from the riders view), I turned these right in thinking this would completely kill the air input and it wouldn't run, but instead it revved it's nuts off. I paniced and span the idle screw. I'm now left with the bike revving like mad no matter where I have the screws or the idle screw. I don't even know if clockwise increases or decreases idle speed now! Sorry for the ramble, but I thought it best to be specific! Can anyone help at all?

 

the THREE screws on the engine side of the carbs are the Sync (or balance) screws.

If you're looking for the mixture screws, you're looking for FOUR screws, one on the engine side of each carburetor, sunken into the body. These are covered by a brass cap out of the factory. They're just behind the carb hats on each one.

The idle screw (located between carbs 2 and 3 on the airbox-side, underneath) turns in (clockwise) to raise the idle, and out (counter-clockwise) to lower the idle.

I recommend that you try and set the sync screws back to where they were after you had them balanced. then, carefully, take the caps off of the pilot (mixture) screws if they're still there, and start at 2 1/2 turns out.

There are two relatively inexpensive tools that make these things a snap: teh Morgan Carbtune Pro for synching, and the Colortune Plug for setting the pilot screws.

Good luck.

 

Thanks man, much appreciated.

 

Just to clarify why your idle went through the roof:

Those screws adjust the butterfly valves of carbs 1, 2, and 4 (3 is unajustable). They are there so you can synch all four to each other. When you turned the one you turned, you opened up that butterfly valve (or two, since the second on from the left adjusts 1 AND 2), and no matter how much you turn down the idle, that one (or two) will still remain open (relative to the other three).

Like losifer said, you are going to have to return that screw to where it was, which might be tricky to find. You might have better luck pulling the carbs, and using a paperclip (or one of a few methods) to set all 4 to a good starting point. Also like losifer said, you will have to fine tune your synch with a manometer, since no amount of "manual" adjusting will suffice. Do a search for bench synching carbs, there is a write up that will help you, I believe it is a sticky in Chat.

Since your carbs will be coming off, perhaps a thorough cleaning should be in order...

 

Thanks for that, I'm gonna have them balanced/synced again today. With regard to mix screws, is it further out = more air?

 

Further out = more fuel = rich mixture=bogging down on acceleration.
Unless it was lean to start with...maybe further out is where it needs to be...I shoulda said that th first time.

 

I'm still struggling with the bugger, it's definitely running rich as it's backfiring, but it still misses unless I accelerate really hard. From time to time, usually in 4th gear, it'll run fine throughout the rev range. I'm totally stuck for ideas now, could it be the yics?

 

It's not the YICS, YICS is just a series of passages in the head.

Backfiring is a lean symptom generally, not rich.

Pod filters cause a bit of a tuning fiasco; there's no easy answer for that.

It sounds to me like you do indeed still have a carburetion issue. Good luck.