84 GS550 pilot air screw

[JakeDeCoste]

Proud owner of an 84GS550E. Bike was smashed 10 or so years ago and sat in basement until i purchased it june 3rd 05'. Got a great deal on with only 16,500 kms on it. Front end was smashed and some small dents here and there but bike runs perfectly true. I bought 2 other GS's for parts and made a good one with the smashed one and still have almost another one geared to go. I started working an industrial shop this summer and got use of an ultra sonic wash and cleaned out the carbs recently. I have a clymer manual and it doesn't seem to give any info on the pilot air screw on top of the carb. It mentions how many turns to put them out on 77-79 models but nothing for my year. The bike has a laser four into one header and stock air filter. I know the jetting will need adjustment to compensate pipe but any advice on the air screw would be greatly appreciated. Thanks Jake

[KEITH KRAUSE]

Correct name for the screw is mixture screw.
It assists the pilot jet flow and allows for fine tuning flow to each cylinder.
Just like the side air screw on VM carbs, your CV carbs mixture screw should be adjusted for best idle using 1,000/1,100 rpm as a base when adjusting. When the optimum mixture adjustment is found, the rpm's should max out. The sweet spot should be somewhere between 1 and 2 turns out.

[JakeDeCoste]

thanks for the quick response. The manual didnt seem to show too much about it. By using 1000 as a base do you mean get the bike idling around there and then adjust the screws. I'm not sure i know what you mean by that. thanks again Jake

[KEITH KRAUSE]

By using 1000 as a base do you mean get the bike idling around there and then adjust the screws. I'm not sure i know what you mean by that. thanks again Jake

Yes, the bike should be idling at the factory recommended rpm when adjusting the screws.
If you think the screws could be set wrong from a PO or you don't know the carbs history, try adjusting them.
Set them initially to a ballpark setting, such as 1 1/4 turns out from lightly seated. Keep a record of their current settings.
Then the bike must be fully warmed up and on the centerstand or level as possible. Idling at 1,000/1,100 rpm.
Start with any carb and slowly turn each screw in either direction until you hear the rpm's max. Fine tune it. Now re-set the idle if necessary to the base idle by using the idle adjuster knob. Repeat to the other carbs.

[JakeDeCoste]

Keith I switched the cleaned carbs on tonite at my friends. Of the two carbs i used 105 main jets and 40 for the smaller jet. Set the pilot screw out 2 turns. The bike is running the best it ever has. no hesitation what so ever. I left the bike at buddies for the night because the crossover tube orings were leaking in the new carbs and it was gettin' late so until tomorow i guess. Thanks again man Jake

Yes, the bike should be idling at the factory recommended rpm when adjusting the screws.
If you think the screws could be set wrong from a PO or you don't know the carbs history, try adjusting them.
Set them initially to a ballpark setting, such as 1 1/4 turns out from lightly seated. Keep a record of their current settings.
Then the bike must be fully warmed up and on the centerstand or level as possible. Idling at 1,000/1,100 rpm.
Start with any carb and slowly turn each screw in either direction until you hear the rpm's max. Fine tune it. Now re-set the idle if necessary to the base idle by using the idle adjuster knob. Repeat to the other carbs.

[KEITH KRAUSE]

You're welcome. Glad the bike is running good. New o-rings will fix the leak.
Let us know if you have any other questions.