Carb leaking (overflow)

[dunkins1]

Ok all, I need your help. I'm looking for every possible failure mode that would cause fuel to leak out of the overflow on the carbs. After rebuild install, carbs were leaking out of number 1. Then taking it off and checking everything out we put it back together. Number 1 no longer leaked but no. 3 & 4 did. Very frustrating. It appeared to happen after some problems with the throttle cable, where we removed the carbs again and turned them upside down to keep the cable attached to the carbs. Not sure that putting them upside caused it but the timing is there.

 

Background; 1987 Royale, 8900 miles. Carbs were rebuilt by a trusted V-max guy. The bike has been synced and runs great except for the gas leak. The tank has been lined (Red) new fuel filter, new air filter, new spark plugs. The carbs didn't originally leak when first installed. So looking for input on all possible causes of the leak.

 

Also, would carbs leak more or less during regular idle?

 

Thanks in advance,

 

Bill

[bkuhr]

Only way for fuel to overflow is float needle not shutting fuel flow off.

 

1. damaged float needle or seat

2. dirt in float needle or seat

3. float does not float, sunk or saturated

4. float out of adjustment

 

Could first try to blow low pressure air thru fuel intake to dislodge dirt in needle port.

Same thing with seafoam soak

 

Failure to sovle here will involve carb removal/ dissesambly again. During reassembly on bench, rig gravity fuel tank above carb, and do float level check before you put back on bike. Redo float level check when on bike with bike fuel pump pressure, before everything else hooked up.

 

Reread tank lined. Open carb drain into clear container. Is fuel red? Tank lining may not be set and clogging float needle open.

Edited August 22, 2010 by bkuhr
addedinfo

[Marcarl]

Replace the filter, you could have a bad one, or installed backwards. Change the fuel lines, they will start to break down, especially if they have been dry for some time. This is in addition to the former post by bkuhr.

[Snaggletooth]

From my experience, and I have had a LOT of problems with over flowing carbs, I'd look first at the fuel filter. Mainly because of the liner in the tank. If it's latex stuff, as mentioned, it may well not of bonded and is breaking down and getting into the system. Seen it too many times.

 

Then again, as mentioned if the fuel lines are original they may very well be breaking down internally and particals getting into the carbs. However I would think the net filters in the carb bodies would clog before the bowls overflow.

 

Now I have to ask...did the rebuilder set and check the fuel bowl levels once the carbs were redone? If the floats are not set properly that will cause the needle to not seat and fuel will still overflow.

 

As far as leaking more at idle......more than likely. If the bike is running under power it is using more fuel so less will be running out the tubes.

 

Another quetion that comes to mind was did the rebuilder do a bench sync on the carbs? If he got the carbs way out of sync one or more carbs may be farther open that the others. Probably not but asking anyway.

 

Just some thoughts.....I got mine to quit making puddles.

 

Mike

[dunkins1]

Thanks all for the input. I'm going to give it another go this week. As far as the tank liner, it was done before I bought it. After replacing the fuel filter (which I'm pretty certain it is in the correct orientation) we had the fuel line off the carbs and turn the ignition on several times to observe the gas. It looked good. I also drained the carbs a couple of times to see what it looked like and I didn't notice any debris. I'll update the group on my progress later this week.

 

Thank you all for taking the time to help me. I really do appreciate it.

 

[dunkins1]

Well, I've isolated it back to clutch side front carb (#1 I think). I took the air filter off and just watched the carbs while it was running. I noticed something interesting. I could see fuel bubbling up through the pilot jet just before it would start leaking out of the overflow, about the same time, I could hear the engine bogging down. What exactly is happening to make the engine bog down?

 

I'm going to try the air, carb cleaner and tapping a couple more times before I take the carbs out again.

[Yammer Dan]

Carefull with the cleaner some of them are too harsh for seals & gaskets. Sea-Foam is great but costley. BerryMan's Chem Tech at Wally World is a lot cheaper but I wouldn't use a lot of it. It sounds like you have dirt in there.

 

I mix BerryMan's And Marvel Mystery oil togather. Works great for me. Both at Wally World. Bout 6 bucks and you got a quart and a half.

[dunkins1]

Carefull with the cleaner some of them are too harsh for seals & gaskets. Sea-Foam is great but costley. BerryMan's Chem Tech at Wally World is a lot cheaper but I wouldn't use a lot of it. It sounds like you have dirt in there.

 

I mix BerryMan's And Marvel Mystery oil togather. Works great for me. Both at Wally World. Bout 6 bucks and you got a quart and a half.

 

 

I have some more sea-foam. Do I understand you actually put a mixture with Marvel mystery oil into the carbs?

[Yammer Dan]

Yes I use a mix of Sea-Foam, Marvel Mystery Oil and BerryMan's Chem Tech. I just had them on the shelf combined them and did a carb soak on a bike I had been having a lot of trouble with and it worked!! So I make my mix out of a large bottle of Marvel Mystery Oil.(32 oz.) a can of Berryman's (15 oz) and about a can of Sea-Foam(16 oz). It works great for me. In a bowl with some parts it seemed to clean better than straight Sea-Foam. Does This make sense?? I DON'T CARE!! It Works.

Edited August 25, 2010 by Yammer Dan