New owner

[Bronzeback]

Just picked up a '79 XS1100. 23K, '81 carbs, pods, aftermarket (I think) exhaust. Project started by a guy who sold to a neighbor, then to me. Good tires, seems to run fine...800 bucks! I synched the carbs today which were out..PO cleaned them but didn't have a synch tool. One of the air screws appeared to be missing, not good. Any ideas on a fix?

Link to facebook photo here

[TopCatGr58]

Hey Bronze,

Welcome and congrats on a great find!

Okay, 81 carbs...you're sure they are 81's!? Will have 4 small ports on the inlet bell, only 1 set of "T" fittings for fuel, the upper fittings on the carb bodies will have been molded/cast closed/sealed. The screw you're talking about IF it's on the front top of the carb body is the Pilot screw, a fuel and air mix screw, not just an air screw. Also if it's an 81, those will be down in a small tunnel. The earlier model carbs had them on the outside of the carb with the screw/spring on the top of the carb pilot screw port.

If it was missing this screw, it would have been next to impossible to tune, get it to idle, synch,etc.!?!? However, if it was missing the AIR JET in the inlet bell, then you might have been able to get it to tune. The AIR JET's can be gotten online, they are actually the small head main jet style jets that Mikuni uses.

Also, there is another Xsive in Richmond(Oldbiker), he's not that active on the Forum, but has a bunch of parts bikes in his backyard!

I'm down here in the tidewater area, Portsmouth.
T.C.

[MindWebs]

I like it. 4 to 2 exhast with turn-outs.
love the flat black... so simple... so nice.
you ever look into a HD bobtail rear fender? (it'd look really nice on there.)

any way...
"One of the air screws appeared to be missing"

HMmm?
i'm not familier with the 2nd gen carbs but....
do you mean "pilot screw needles"?

if so ebay "geogefix" good place to get all your carb rebuild parts from
4 kits ALL needed parts all jets needles float valves and seats gaskets
blah blah blah. full set up. $74.00 with shipping to my door.

he sells single parts to i think.

hope it helps

Webs

[CatatonicBug]

if so ebay "geogefix" good place to get all your carb rebuild parts from

That's "georgefix", actually. He does seem to have lots of parts, at decent prices. However, he's not an expert on all the differences between the years/models.

I got my carb kits from Z1, and it came with all the jets and the mixture screws.

[Bronzeback]

The PO said the carbs were from an '81, which is what he was told...but there are two gas lines. With the tank off looking strait down #2,3,4 have the air/fuel mixture screw but not #1. I like to learn but am not well educated on carb work. I have the tool and have learned how to synch them though, and I did that yesterday, despite the missing screw (they were way out). I'll post pics when I get a chance, thanks everyone!

[CatatonicBug]

I have the tool and have learned how to synch them though, and I did that yesterday, despite the missing screw !

Is that even possible?? I would think the missing mixture screw would basically make that carb non-functional...

[Bronzeback]

Yea I woulda thought so too...maybe it's not missing but broke off? I need to take a better look

I was just looking... "old biker" is my neighbor...lives about 10 houses down!

[DiverRay]

Someone MAY have tried to change carb bodies on the rack. You may have the #1 carb as an 80, and the rest are '79's!! I HOPE not, but anything CAN be made to work. The one BIG difference is the vent system for the carbs. The early carbs have TWO "T" fittings, the top "T" is a vent, and the bottom "T" is the fuel inlet. The vent tubes went to the airbox, but can just have a fuel fulter put on to keep bugs out. The later carbs have the vent built into the inlet bell of each carb, and don't require the top "T".
It sounds as if you need to go see oldbiker with a 12 pack of beverages and talk about bike parts!
Welcome to the site.

[CatatonicBug]

I was just looking... "old biker" is my neighbor...lives about 10 houses down!

Maaannn... You're lucky... All I had locally was a Harley guy across the street from me. I had to do everything via this website!

Would have been nice to have someone local who actually had seen one of these bikes before.

[boyat68]

BronzeBack:



This is an 80 Carb with the Pilot Tower and the air screw inside. The recommended starting position is 1-1/14 to 1-1/2 turns out.

[DGXSER]

Is #1 missing the screw? or does it just still have the plug in it, a silver or bronze disk stuck into the top of the tower with a small hole in the middle.

Another way to tell what year the carbs are is the inlet bell. Like Phil stated, the newer model carbs have the vent in the inlet bell and therefor have four holes in the inlet bell, the older models only have three holes as they do not have the vent.

[boyat68]

BronzeBack:



This is an image of the parts that go into that Pilot Air Screw Tower.

[Bronzeback]

I took the tank off again for a closer look. That screw simply appears to be gone but it must be broken off and still half in there....Synched, idles, rides fine. Still, I'll pull them and dig in at some point and post pics once I get them out of my camera. Pleasure to meet Old Biker again today. He was outside as I rode by. We swapped some stories, I let him take her for a spin and he agreed...Nice purchase!

[Bronzeback]

OK so I contacted the P.O. and he said all the screws were there when he adjusted them, but he remembered that #1 did feel like it wasn't getting any friction when turned. Also invited me to pick up a bag of misc. pieces from his work and the other P.O.'s work. In that bag is a small bag of carb parts. From looking at the pics on this thread I've identified 5 pilot screws in the bag, which indicates someone went to replace all four, but held one back. Kinda hate to mess with it since she's running fine as is but still, that missing srrew bugs me! From the other pic on the thread of the pieces inside the tower I can see I have them all, except for what looks like an o-ring in the pic...is that a standard size I could pick up at the auto parts store? Next question can the screw be put back in with the carbs on the bike or is dissassembly required?

[Ken Talbot]

The recessed screws like the one in the photo are on the 80 and 81 carbs. The point is quite blunt and not prone to breaking off. The early carbs were the ones with the screws with the delicate points, and they have a very obvious head sticking up above. If you're looking in the hole and it simply appears to be gone, you're probably looking at the little cap that Yamaha put in over the screw to keep folks from tampering with it. Search a bit more for the article about carefully drilling and removing that cap so you can get to the screw.