Yet ANOTHER carb question

bswinn

XS650 Enthusiast
Messages
52
Reaction score
0
Points
6
I need some help Ladies and Gents...

I have some carb issues. I'll try and describe it as briefly as possible but feed you all the relevant information.

Mikuni 38's with a carb rebuild kit and pods. Started leaking gas out of the pods. Turns out the floats weren't adjusted right. So I fiddled with those and now have them adjusted with a sight tube so the fuel is at the VERY bottom of the lip on the main body where the bowls mate into. Turn the fuel on and wait 10-20 minutes and no dripping. But there is a little ring of gas sitting inside the throat of the carb around the outside of the needle jet emulsion tube. Wait another 20 minutes and it eventually start dripping but VERY slowly.

Take the tubes out, O-Rings are kinda shot but not totally. Wrap some gas certified teflon tap in the seat under the o-ring as a test. Install and the little ring of gas still comes in. I try the same thing with some gas certified gasket sealant over the seat of the emulsion tube. Same thing happens. I break the carb down, clean out the teflon, gasket sealant and all and buy some 4mm by 1mm o-rings from McMaster and install after lubing up the o-rings with some motor oil.

NO DICE!!! I still have that ring of gas around the emulsion tube inside the carb body throat.

I adjust the floats until the fuel level is DRASTICALLY lower than all the manuals suggest and the fuel STILL shows up. The incredible thing is that even with the fuel level so low if I move the slide/needle I can see fuel inside the tube. So what it seems to be is that capillary action is allowing the fuel to climb the needle over the top lip of the tube to cause this puddle.

Any ideas or suggestions. I've been at this for nearly 2 weeks. I've attached some pictures. The two showing different fuel levels is just as a reference to where I'm setting the fuel height.
 

Attachments

  • Carb 01.jpg
    Carb 01.jpg
    159.8 KB · Views: 164
  • Carb 02.jpg
    Carb 02.jpg
    176.8 KB · Views: 159
  • Carb 03.jpg
    Carb 03.jpg
    207.9 KB · Views: 174
Have you tried riding it? Does it run well and not rich or lean?
Leaving the fuel turned on for 10 to 20 minutes without the bike running isn't reccomended. I don't think most peolple have checked under those circumstances.
I might try running it and seeing how it acts and turn the fuel off when the bike isn't running.
Leo
 
I got the bike running last night. It seemed to be running very rich. It was sputtering and such and there were little wet spots on the ground from the exhaust. I attributed this to either an ignition issue or butterfly adjustment or idle circuit adjustment since I havne't done any of that tuning.

Today I emptied and dried the bowls and lowered the fuel level just a little bit once again. I then let the gas tank fill up the carbs and as soon as the fuel level stabilized I turned the fuel off. Came back after 20 minutes and there was only a faint hint of fuel. So I let it go for a while more with the fuel off and there is more fuel there. Checked like 3 hours later and the fuel ring is still there around the emulsion tube but it didn't get any larger.

It's weird because I've read through these forums time and time again and don't see anyone with a similar issue. I don't get it.
 
It sounds like you have slow leaking float needles.
 
That's what I thought too. So I swapped the carb kit replacement ones with the old ones. It's happened with both sets. Is there any way of possibly doing a light lap or something to set the needles into the seat a little better?

I would think that if it they were slow leakers that it would always overflow but I left them setup last night with fuel in then and the fuel from the tank shut off and the little ring of fuel didn't get any bigger.
 
If you want to "lap" the seat wrap steel wool on a q-tip.
If you were to run the motor after you close the petcocks that weep would go away.
If you just shut them you still have gas in the line above your carb bowls. Gravity works 24/7.
 
Back
Top