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About to give up in leaky carb..help

  • Thread starter Thread starter claygs750e
  • Start date Start date
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claygs750e

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Ok, so I've been dealing with a leaky carb for a month now and have tried everything including:
-complete tear down and dip of all components
-all new orings
-stage 3 kit installed
-all new needles and seats
-floats in good conditions
-new gaskets
-adjusted the float tabs to spec 22.4
-adjusted the float tabs higher and lower than spec
-attempted to check float level using tube from drain, but not sure if I did it right.

So when I start the bike it runs for about a minute and when on the center stand it starts to leak a lot from carb 3 and carb 2. I'm at the point where I've adjusted the tab in so many ways I have to be missing something. Please help as I've been troubleshooting this for a month and about to give up. Thanks guys
 
It starts leaking from the overflow tube and comes out the main area where the pods attach to. It doesn't appear to be leaking from the gasket, it seems to me the amount if gas it's leaking that the needles arent stopping the flow of gas, but I've adjusted the tabs so many times and I've tried the OEM needles and now a set from Z 1
 
have you checked to see if the fuel tap (petcock) is faulty? is there fuel coming out of the vacuum port on the tap?
 
The petcock is brand new and when I when I try to bench test the carbs fuel level I use the tank so when it's in the on position it stops the flow, but when I turned it to prime and sucked the vacuum line to get it started the gas overflowed . I thought that was normal since it was turned to prime
 
I'm sorry, I meant the vent hose is where the gas pours from. I have the vacuum style petcock so I thought if the carbs are off the bike I need to create vacuum to get it to flow initially. When I connect the gas and vacuum line to the carbs on a bench and turn it to prime nothing will flow into the carbs unless I put suction on the vacuum line and then it will flow. If the petcock is on the run position nothing will flow either. I thought if I turned it to prime it would just flow with no assistance but I need to create an initial vacuum
 
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those petcocks do need a puff of vacuum to get them started on prime. once they start flowing they continue to flow with no vacuum.

can you post up some pics of the carbs, preferably the bottom half, without the bowls on
 
I'll snap some pics when I get home in a few. In general though if I'm trying to see if the carbs will leak on the bike should test it on the bench using the prime setting. I would think that if the gas flows on prime on the bench the floats will rise seating the needle and then the flow would stop and ideally nothing will leak correct?
 
as long as the carbs are set at the same angle on the bench as they would be when bolted on the the bike then yes, it should give you an accurate setting
 
When they're on the bench I have them in a vice with a level ontop so they are level. Is there a way I could bench test each individual carb body so I can isolate the problem?
 
i suppose you could take the float valves out and make a suitable plug, to block the seats from passing any fuel. then block one carb at a time, turn on the fuel tap and try and isolate the problem carb that way. or just force the valve into the seat manually and hold it there with a bit of chewing gum or something!
 
Here are some pics of the carbs and the setup I'm using to test:







 
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When you changed the float valves out did you also change the seats? Looks like you have the original seats still installed.

Did you measure the float height from the carb base (no gasket) to the flat area just before the step up?
 
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I'm sorry, the seats are original.

Ok so here is a test I just did that makes me think it's the float height again even though I had it as high as 26mm. I removed the bowls and taped all the floats in the sealed position with the needles in place. I placed the carbs with the floats upside down like it would be on the bike. I connected a fuel line and with fuel in the line and the floats taped down there was no leaks. I checked the seat seals, and needles and everything was dry. Obviously when I untapped each one fuel came out.

So does this mean it's really the float height and they are not pushing up far enough to seal the needles? I'm bent that tab pretty far so if it's not pushing up on the needles far enough what could be the problem? Could it be the seats since it's obviously seating ok.

When I measured the float height I started without the gasket to the correct portion of the float based on the picture in the manual and started at 22-23mm. I started playing with the tab and went all the way to 25-26mm and it's still leaking. Just to make sure I'm not doing this backwards when I bend the tab I'm bending it toward the needle if I want it to seat quicker and let less gas in right?
 
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Correct on the bending the tab to lower fuel level. Are all 4 carbs leaking? Still concerned with the original float valves seats and after market valves. I've found the aftermarket valves to be slightly shorter then the OEMs.
 
The last time they were on the bike carb#2 and #4 was leaking. I bought the needles from Z1 and they look identical to the ones I pulled out. I even put the OEM back in with no change. How far out of spec should I bend the tab to get it to seat quicker? I'm puzzled
 
my money is on the float valves fitted into original seats. if they seal with a bit of extra pressure (taped on) then they are not sealing correctly with the pressure of the float.
sorry to say this but i would replace all the valves and seats with new matched pairs.
 
It should seat at the correct float height. The whole purpose of setting the float height is to ensure you have the correct amount of fuel in the float chamber for the jets to meter the correct amount of fuel. You shouldn't have to mess with the height in order to get the float to seat. My guess is that the seats themselves need to be replaced along with the new needles. I'd set everything to the correct height. If you have a leaking carb on the bench then move the seat from the leaking carb to one of the none leaking carbs and see if the leak moves with it. Also make sure you have a new intact O-ring around the valve seat assembly. Make sure the O-ring is not cut or pinched. I use some grease to lube the O-ring before I insert the valve assembly into the body.
 
If I bought the needles from Z1 then the seats from the same site should be a matching set correct? The only issue I have with this is I had the leak before I even bought new needles so they had the original seats and needles. I'll try anything at this point
 
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