Needle Valve Seat(?) Question

[shade]

My 83 XS650 has been running worse and worse lately. It sat for a couple of weeks and now is backfiring through the carbs. I am cleaning the carbs and the only thing that was really messy was the area below what I think is the needle valve seat?
Sorry if I am calling it by the wrong name and that's why I've attached a photo. The screens were filled with crap as well as the area beneath them. I've cleaned them out but do they need an O-ring or anything else other than what is in the picture?
Thanks

 

[shade]

I think I mean Float Valve....

 

[5twins]

That's your float needle seat. Just that o-ring on it is all that's needed. Make sure it's in good shape because it seals the seat into the carb body.

 

[fredintoon]

Hi shade,
thing is, most times you can't tell a good carb needle & seat from a worn set.
Safest way to go is replace them both (like a drive chain & sprockets, they are best renewed as a set)
You'll find the new set won't have that little dome filter.
Salvage the existing filter or go with the majority and decide they ain't worth the bother.

 

[shade]

Hi shade,
thing is, most times you can't tell a good carb needle & seat from a worn set.
Safest way to go is replace them both (like a drive chain & sprockets, they are best renewed as a set)
You'll find the new set won't have that little dome filter.
Salvage the existing filter or go with the majority and decide they ain't worth the bother.

I replaced the O rings but you're saying I should replace the whole thing? I will put it on the list of things to order, THANKS.


After I put the carbs on the bike today it started easily with no choke, and then ran better than ever UNTIL...
After a few miles it started backfiring, not loudly just little jolts. Then it went away so I kept going. Another couple of miles and all of a sudden it becomes very sluggish and I see gas dribbling out of the pod filters. Then it just stalls completely and I coast into a parking lot. Somehow my tool kit is missing the Alan wrench to get the carb boots off the bike but I get the carbs off enough to open them up and blow them out a little. At this point I'm pretty worried because I'm around 10 miles from home. I start the bike up and theres no problem the whole way home except for the engine revving in neutral which is probably from me routing the throttle cable improperly when I put the tank back on.
Does anyone have any ideas as to what might be going on?
The bike's got just over 3000 miles on it.

 

[Richardg]

I generally replace the float needles and seat as a set, in both carburetors at the same time. You could have gotten a piece of grit or varnish in one of the lines or pilot circuits. "Starts and runs fine then gets worse" makes me think of fuel delivery. A petcock could be getting plugged, Partially plugged fuel filter, or a plugged vent hole in your gas cap. Plugged pilot jets which is not all that uncommon on a bike that has been sitting for a while. A plugged pilot jet will cause it to run lean and could cause hovering idle once it's hot. Float levels could cause that problem. Also a malfunctioning centrifugal advance, which is something you can just check with a timing light. A bad coil that is old can become weak once it's hot. I have two XS650 I ride all the time. both had the carburetors off and cleaned several times in the first six months, to clear the pilot circuit. Even with inline filters they still manage to pick up some crap, but one that was sorted out they are both trouble free.