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air screw and pilot adjustments

  • Thread starter Thread starter Anonymous
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Anonymous

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I have a 1981 gs1000g. I have rebuilt my carbs. I replaced the air screw adjment screw and the pilot jet. what are the recomended settings for these two? when i pulled these two out they both were screw fully in and filthy!!!!! yech!!! So, is there something close to an optimal setting or a procedure to finely tune these adjustments? thanx!!!
 
Re: air screw and pilot adjustments

terrancemoore said:
I replaced the air screw adjment screw and the pilot jet. what are the recomended settings for these two? when i pulled these two out they both were screw fully in and filthy!!!!!
Click to expand...

Kinda confused about what settings you're looking for...The pilot jet is a tight tolerance #40, but there is no adjustment on this...it just screws in until seated. A word of warning here...we learned the hard way that there are two kinds of #40 jets. The tight tolerance one used in this bike has fewer holes and a smaller 'bore' than the regular #40.

The 'pilot screw' is 'factory preset' according to the manual, but ours were about 1-5/8 turns out (CCW) from fully seated...fully seated being just gently bottomed out. This is actually a gas/air mix which is controlled by this screw, affecting the idle/slow system. Experience shows that screwing it in (CW) leans out the mix, and conversely, screwing it out (CCW) richens the mix.
 
Screws.

Screws.

Someone else mentioned that they started with theirs 2 turns out and adjusted from there.
 
Pilot Screw adjustment

Pilot Screw adjustment

Hi

I have been trying to sort out my 1980 GS1100 pilot screw settings and have had some success in cleaning up the plugs on No. 2, 3 and 4 (No. 1 is still a problem). I started at 1.5 turns and the engine was popping a lot so I ended up with them out anywhere up to 2.75 turns. The service manual says to set them at 3.5 turns so I did that today and No. 2 and 3 look all right and No.4 was a bit sooty. No. 1 was more sooty. I was going to run them further in when the battery was getting run down so I stopped for the day.

I don't know if the carbs on my bike are different (it was sold into Canada and perhaps they had a different series of carbs for this market). The threads are very fine on the pilot screws (I took No. 1 out last night hoping to see a problem - looked good). The carbs are BS34SS with the numbers 49210 and B981 on the carb bodies.

If this was any easier, I don't know if I could bear the fun.


Patrick
 
Pilot Screw adjustment

Pilot Screw adjustment

Hi

I have been trying to sort out my 1980 GS1100 pilot screw settings and have had some success in cleaning up the plugs on No. 2, 3 and 4 (No. 1 is still a problem). I started at 1.5 turns and the engine was popping a lot and would not idle at all so I ended up with them out anywhere up to 2.75 turns.

I discovered that the service manual says to set them at 3.5 turns. I did that today and No. 2 and 3 still looked all right and No.4 was a bit sooty. No. 1 was more sooty. I was going to run No.1 and 4 further in when the battery was getting run down so I stopped for the day.

I don't know if the carbs on my bike are different (it was sold into Canada and perhaps they had a different series of carbs for this market). The threads are very fine on the pilot screws (I took No. 1 out last night hoping to see a problem - looked good). The carbs are BS34SS with the numbers 49210 and B981 on the carb bodies.

If this was any easier, I don't know if I could bear the fun!


Patrick
 
I have a 78 GS750 and have had a great deal of fun !! with these screws. Anyway, here is what I finally did.

Ensure carbs are clean, jets are clear, float heights set.
Set air screw 1 1/4 turns out.
Set pilot screw 2 turns out.
Balance the carbs.
Run the bike for a few miles.
Observe plug colour.
Turn pilot screw in to lean, out to richen.
Ride the bike again and adjust pilot screw as neccessary.

I also tried adjusting the air screw but found that by adjusting both screws on all carbs got me in a right mess.

Only adjust one thing at a time until no more adjustment is available.

Some people adjust float height to affect mixture. However, the manual has details of float height and air screw setting, so I set them accordingly and have faith that they are correct. The only thing that isn't specified is pilot screw setting, this is merely identified as factory set. So it makes sense to me that this is the screw to adjust.

The bike runs great now, crisp and responsive. I do have a slightly lumpy idle though but I am not going to 'tweek' anymore.
 
mad

mad

hey mad on what side of the carbs is the pilot air screw at, airbox or motor side?
 
On my setup, air screw is on airbox side, protruding from the carb to the side, accessable from above.

The fuel screw is located beneath the carb, next to the floatbowl, sitting in a round 'shaft' (for want of a better word) accessable from beneath (with the carbs in place if you are dextrous !!)
 
What a great site! I just put new mufflers on and then logged on to find information on setting the carbs. The first thing I saw was this topic. I did as the MadHatter suggested, took it for a test ride and it ran beautifully. Thanks MadHatter, I will probably have to make some minor adjustments when I put new plugs in, but for now, I am elated!
 
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