petcock or carb prob? how to sync carbs?

[B.B.]

Hey guys sirry for the long post but I am starting to get a littlefrustrated. I got this bike two months ago and it had sit up for a year. I replaced battery, throttle cable, cleaned brakes, and carbs but not well. Replaced starter button and got the bike to turn over. Cleaned carbs again (better) this timeand got the bike to crank but would die when I put it under a load. Pulled carbs again and the bike ran and I drove it down the road and it was leaking oil out of airfilter housing. Do to overfilling(I drained middle gear oil instead of motor oil). Got that fixed and sprayed cleaner in carbs. Then I pulled gas tank and cleaned it and the petcocks. Now when I crank the bike it will start and idle a little high for a time and then idle back down but when I rev it up it acts like it sticks and stays idleing high until u try to take off. Last night I went to take it for ashort spin after cleaning the carbs for the third time. It took off fine but when I reached a higher rpms to shift from 1 to 2 it started cutting out. I put it n 2 and it ran fine until I reved up anf when the rpms reached high enough to switch gears it cut out again. Don't kbow what's going. Ok here is my Q's. Starting with the petcocks. The manuel says to turn the Petcocks to on or reserve to remove them. Mine pour fuel in all but the off position but since I cleaned them one is leaking no matter what position its in. Leading to the carbs. My carbs have had problems leaking fuel out the carb throat (since I have not hooked up the airfilter case while I'm checking the carbs). But when I take them apart the float moves freely. Is there away of checking the floats with out removing the carbs every time? I know the carbs need to b synced but not sure how and if I can leave the carbs on the bike when I do? Leaking carbs I think could be the float but they seemed to move freely. The high idle getting hung I think may be to much fuel or not enough air. Could this be caused by the petcock leaking, the carbs not synced, or because I didn't hook up the air filter case. I have several forums on here and think maybe the reason its cutting out and dying is because its gettin to much fuel but don't know. Sorry for the long reading and thanks in advance for the advice. Please help.

[B.B.]

By the way, I have checked for a vaccum leak around the carb boots and it idles the same. So I don't think that's my prob.

[crazy steve]

First, tell us which year/model bike you have; that can make considerable differences in diagnostic advice...

[B.B.]

Sorry, its a 1980 xs1100 special.

[crazy steve]

Ok, on the petcocks, fuel flowing when they're not in the 'off' position is normal ('standard' petcocks don't have a 'off' position, but also don't flow fuel unless the motor is running). On your Special, you're also supposed to have a vacuum operated valve under the tank, but many owners remove that. If one is leaking even when off, it probably needs to be rebuilt.

If you've had the carbs off and/or apart, they'll need to be syncronized, period. Fuel leaking/flooding could be several things, but the most likely culprit (if you still have OEM carbs) is the o-ring seals on the float valves. If you don't know when they've been replaced, they probably should be. The valves themselves could be bad, but try the o-rings first. Georgefix (a eBay seller) has both the petcock and carb rebuilt kits.

Unfortunately, you'll have to pull the carbs to get at these items. And running the bike without the airbox connected will cause poor running. The carb sync has to be done with the carbs on the bike and all bits in place.

[DGXSER]

For the O-rings, you can go to Harbor Freight, they sell a nitrile and a Viton o-ring set. Nitrile set is about $5 and will have the o-rings you need to replace the ones for the float valve seats. If you recently replaced the valves, that is the most likely culprit.

[B.B.]

Ok thanks steve I will get those synced but I'm still not sure about the o-rings on the float valve. What and were is that located. In taking apart the carbs the only gasket I saw was the one on the float bowl.I am not sure the float valve had an o-ring on them, and would this cause the lean fuel prob that I think I'm having

[crazy steve]

If you haven't already found this, here's a nice pictorial run-through on your type carbs. Look here: http://www.xs11.com/forum/showthread...b+cleaning+101

[B.B.]

Thanks that was helpful. I have done most of what that said except remove the enrichment valve or the float valve seat. This may be a dumb question but how do u remove the float valve seat amd is that were the o-ring is at. I have removed the float and float valve but could not remove the seat. Again could this cause the carbs to leak fuel out the carb throat and cause the bikes idle to hang when you rev it up.

[fredintoon]

- - - how do u remove the float valve seat and is that were the o-ring is at. I have removed the float and float valve but could not remove the seat. Again could this cause the carbs to leak fuel out the carb throat and cause the bikes idle to hang when you rev it up.

Hi BB and welcome,
your profile sez you have a 1980 Special (you should put that in your signature)
The float valve seats are held in by a C-shaped keeper plate that is retained by a single cross-head screw.
Remove the screw, lift off the keeper and the seat pulls out of the carb body. There's an o-ring around the outside of the body that's most likely gone all flat so it leaks gas into the float bowl even if the needle is sealing properly.
And my favorite carb trick:- work on them in a cafeteria tray so the parts can't fall on the floor and disappear.

[B.B.]

ok guys I got the float valve seat fixed and the carbs no longer leak. Yea THANKS! But the bike still sounds like its getting to much fuel. When I start the bike it idles ok then when its worm and I rev it up, the rpms stick for a short time and then idles back down. Also when I rev it up it sometimes makes a popping sound not backfire. I went to take it for a ride and it is still cutting out when it reaches higher rpms. Any suggestions?