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Pilot Screw settings on 1981 GS750L

  • Thread starter Thread starter Detman101
  • Start date Start date
D

Detman101

Guest
Greetings all,

In my eagerness to put the carbs back together without an official manual, I wound up taking a bit longer to think about things....like a FEW DAYS longer!

What I would like to ask is if there are any particular settings for the Pilot Screws on the carbs of a 1981 GS750??

I figured that the air screws have a setting so the Pilot screw may have a particular setting too. I just want to have everything right before I put these carbs back on the bike and try em out.


Thank you in advance,
Dm of mD
 
Anyone?
I'm kewl though, i know its the holidays. Everyone busy with the family hehe.

:)
Dm of mD
 
I've got an 81 GS750L and I can check for you. I also have a manual for it and I can see if they recommend a starting point.

It will probably take me a few days as we are leaving for El Paso in the morning.

I probably won't get a chance until we get back.

Mike
 
Not a problem, I will wait until then unless someone responds first. I appreciate any and all help. I can't wait until my manual gets here...

Dm of mD


mdole said:
I've got an 81 GS750L and I can check for you. I also have a manual for it and I can see if they recommend a starting point.

It will probably take me a few days as we are leaving for El Paso in the morning.

I probably won't get a chance until we get back.

Mike
Click to expand...
 
Pilot screws don't have a particular setting. They are for fine tuning each cylinder because there are small differences in each cylinder. The factory sets them using an emissions analyzer. On the VM carbs, they are generally 3/4 to 1 1/2 turns out. On CV's, they are generally 1 1/2 to 2 1/2 turns out. Turning them out allows more mixture in.
As for air screws, regardless of if the motor's stock or modified, they should be set to achieve the highest rpm at normal operating temp'. Then re-set the idle to the proper speed by using the idle screw knob. Turning them out allows more air in. To more easily hear the rpm's, adjust "2 at a time" in 1/2 turn increments.
Take some plug reads after slow/city riding and adjust the pilot screws as the plug colors tell you to. It's common to end up with all 4 pilot screws set a little differently from each other, just like a new bike comes from the factory.
 
:(

Geez, before I got into this I was only knowlegable about setting the fuel mixture screws. I thought that all the other screws/jets were just put in and tightened down gently.
To find out now that I have to go back and put a setting on those pilot screws/jets is slightly dismaying.
Perhaps I should take this to the shop...I'm having doubts.
Finding out about these pilot screws makes setting the mixture 4 times harder now than it was before. I will try a setting of 1.5 turns out across all four of them and just adjust the fuel mixture screws. That way I will at least know that the pilot screws are all at the same setting and just work with the fuel mix screws.

I didn't expect this to be so complicated. :( It's hard without a manual...

Dm of mD
 
Well, I have come to this conclusion.

If the mixture winds up being too rich I will lean it out by putting pod filters on the carbs and try to match all the mixture settings to the richest carb.

If the mixture winds up being too lean I will adjust the fuel mixture screws out to allow for more fuel flow.

If it actually runs right with the carbs & Airbox hooked up I will pat myself on the back and go for a christmas ride.


When I get my manual I will go back and get things right or have the shop tune my carbs after the holiday (Last resort)
Stealerships suck.

:?
Dm of mD
 
I found the settings.

For my bike its 1.5 turns out on all screws...Pilot and fuel mix.


Dm of mD
 
What kind of carbs does your 81 have? My bikes only have 1 setting on each carb. It's the one on the cylinder head side of the carb and it's up top. All of the other jets just screw in. The needle may be adjustable on your bike but you probably didn't touch it during a cleaning.

Steve
 
Now you're getting me mixed up. In your first post you said you have pilot screws and air screws. Now you say you have pilot screws and mixture screws. My Suzuki factory manual says you have only pilot screws. There is no "setting", if you read somewhere that it's 1 1/2 then they are just giving you a general setting, not an actual factory setting.
Pilot jets and main jets do have threads. The jet needle fits in a hole and is held in position by a clip. Jet kits include a jet needle that's adjustable.
If you install pod filters you MUST re-jet with an adjustable needle or you will run very lean and hot. Pod filters require a larger main jet, a richer needle adjustment, sometimes larger pilot jets and adjustments to the pilot (mixture) screws. If you think you can install pod's and simply adjust the pilot screws to compensate, you are wrong. The pilot screws only HELP regulate the jetting at idle and at slower speeds. During normal riding/cruising, the needle regulates the jetting. The main jet regulates the jetting after 3/4 throttle.
If you stay with a stock air box, the 1 1/2 out on the pilot screws sounds fine, as I previously posted. You still need to get plug reads and fine tune each cylinder by adjusting each screw, if necessary.
 
You're right Keith. I am going to work on the rest of the bike until I get the second set of carbs this week and my stage-3 jet kit. I'll have the shop clean the new carbs and install the jet kit as well.

Thank you for clearing that up man. I would have wrecked my engine if it wasn't for all of you on this site.

Thank you everyone!! This site is a true blessing!

:)
Dm of mD
 
Pilot Screws

Pilot Screws

Are you guys talking about the small screws that face the airbox when you say pilot screws? When I took my carbs apart on my GS850 I swear they were in as far as they would go. I tried tighting them before I backed them out to see if there would need to be any adjusting when put back together and they would not go in any further. This also may have been due to the fact they have not been touched since they were installed in 1980. I don't know. Jets, needles, screws, valves, who came up with all these complicated similar terms anyway? I have not put mine back together yet so I can't give any rebuild info yet...... but I am sure I will when the time comes.

Curt
 
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