Air-fuel pilot screw question

[Anonymous]

I'm cleaning up another set of Mikuni carbies for the GS1000G, coz the ones on the bike have been damaged by a gorilla fisted mechanic sometime in the past.

I took out the air fuel pilot air screw and spring and noticed there was also a flat washer in there and then an O-ring in the bottom of the hole. The O-ring fits the hole but at that depth the screw itself is nowhere near that diameter so it doesn't seal the screw at all.

So what does the O-ring do?

Or is is in the wrong place?
I thought it might go around the top of the screw but there is no indication of where it could fit. The Suzuki manual does not have the exploded view of the pilot screw (the only bit missing from the parts diagram), and it is not clear from the other pics of the carby.

Anybody know how the screw etc should be assembled?

Kim

[Billy Ricks]

It's assembled the right way. Spring, washer, o-ring. It's just there to keep leaks from happening around the thread of the needle. Worn out o-rings could effect idle mixture.

[KEITH KRAUSE]

Which screw are you talking about? The pilot screw is the one under carb,the fuel/air mixture screw is on the side at roughly a 45 degree angle.The pilot screw has a notch for the o-ring just below the head,then there are threads,there is no washer,then the spring. The fuel/air mixture screw has a place for the o-ring just below it's threads,it actually sits on top of a 'washer' that is really a part of the screw,then you have the spring. This keeps the spring from digging into the o-ring,they must be separated. My bike is a '79 GS1000EN,but it could be there are small differences in carbs. KK.
PS:For smog reasons,the '80 carbs had a modified pilot circuit (leaner). Otherwise they look identical to '78/79 carbs. Be sure what you have. The '78/79 have a sharp tipped pilot screw,the '80 used a blunt tipped screw and was capped by the factory.

[SqDancerLynn1]

He's talking about the BS vacuum type carbs 1980 up. If you need the
o-rings Search the forum for Robert Barr he sells a complete set of O rings for $12

[Anonymous]

Today I took the old carbies off the motor and checked out what they had. Same setup.

However, the O-rings have now come back to normal size. The carby cleaner stuff had made them swell, as it did to others in there as well. Now they all seem to be OK.

Thanks for your input.

Kim