Bladder Problem on My '85

[FJ1100mjk]

Hi:

Took my '85 for a ride tonight, and this was after doing a bunch of work to it in the last month or so. Front forks flush and freeing up the preload adjusters, new straight-wound springs, completely going through front brakes and anti-dive units, new chain, new tires, AND doing the stiffer spring and new o-ring thing for the petcock. The latter was in response to the (continuing) problem of having the bike leak out a small amount of gas after I ride it. Doesn't show up right after I shut it off, but appears about a half hour later. I don't understand it, because I went through the carbs thoroughly, installing new float needles and seats, and carefully adjusting (what a drawn out process!) the float levels to within spec.

The bike runs great, and I feel good that all of the work (and money) that I put into it has paid off, yet I am plagued by this nagging problem with the gas leak. Any thoughts?

I wouldn't be suprised if the carbs have to come off again, but everyone who's done that, and put them on again, knows that it's a pain.

Thanks in advance.

Marty

[Pat Conlon]

Hey Marty,  

If it's not the carbs, then there could be only 1 thing left.

DavidR had a hell of a time getting his petcock to stop dribbling. So after reading what he went thru with different O rings, etc... I said, screw it and bought a new petcock assembly. Less than $100 from Power Sports Plus.
See my post here: http://www.fjowners.com/index.php?topic=6469.0

[FJmonkey]

Oh! I thought you had a problem with distances between long ride stops kind of bladder problem. Sorry, as you were.....

[racerrad8]

Side stand or center stand?

Either or both?

Randy - RPM

[SlowOldGuy]

I couldn't get the petcock or the carbs to stop leaking.  I tried several different (old) petcocks that I had, all kinds of o-ring and spring combinations, nothing would stopo the fuel.  

The carbs were just as bad, swapped several needle/seat assemblies, new floats from Randy, float tweaks, etc.  If I let them sit for several hours under a tank of fuel, one (or sometimes more) would start seeping.  Just a slow drip that would not stop.

I finally had enough and installed a new petcock and a complete new set of late model carbs from Randy.  Still running a gravity feed with pump-sized needle seat diameters.  

Still haven't had time to further diagnose the original carb set.

DavidR.

[bugboy]

I've got an '87 with a later model tank and petcock and had the same issues. I installed a fuel cutoff switch/petcock from Dennis Kirk that pokes out the right side cover and haven't had any problems since.

Kind of cheese-y fix, but it was cheap and quick.  I think I spent about $15 - $20 with the new petcock, fuel line and clamps.

[Pat Conlon]

 Still running a gravity feed with pump-sized needle seat diameters.  

Yea, I remember what you went thru David, made me think that it was the best $100 I've ever spent.
Hey, I got 27 hot sweltering summers and148k miles out of the oem '84 petcock so the next oem should be good for a few more summers and miles...........

How's those little needle seats working out for you? Any full throttle starvation?

[FJ1100mjk]

All, thanks for all of the replies and ideas.

Randy, for the most part, I have been parking the bike on its centerstand when I return from my rides. the bike is on pretty much a level surface in my garage too. And, the gas seeping stops after its initial spew. Hope it doesn't come to a new petcock setup, but it's really frustrating dealing with this fuel leaking issue. Especially now that a lot of the hard work is out of the way and the bike is running great.

Marty

[racerrad8]

Can you determine which hose it is coming from. I suspect it will be coming from one or more of the small hoses that are the choke enrichment circuit.

Do you have the complete rubber back heat shield under the carbs. I suspect the bowl(s) are heating and causing the fuel to purge through the choke circuit.

What float level did you adjust too.

Randy - RPM

[FJ1100mjk]

Randy:

The heat shield is installed. I'll need to ride and park to update on what hose(s) the fuel may be coming from. Perhaps tonight after work.

I set the fuel level in the bowls at approximately 3mm below the gasket sealing surface on the carbs bodies.

Marty

[racerrad8]

I set the fuel level in the bowls at approximately 3mm below the gasket sealing surface on the carbs bodies.

Marty

Is that via fuel level when mounted on the engine at the angle or off the engine measuring the float to the gasket surface?

Randy - RPM

[FJ1100mjk]

Randy,

The carbs were off the bike, mounted on a test stand that kept the carbs level to the horizontal. I used a clear piece of tubing connected to the carb's drain and held that vertical to the carb, then filled the carb up with fluid, waited for things to stabilize and noted the fluid level in the tube relative to the gasket sealing surface. I adjusted the floats ever so carefully (many times) and repeated the process to get the fuel levels at the aforementioned levels.

Marty

[racerrad8]

Floats are going to be too high. The carbs mount on the engine at a downward angle. When float is high the choke circuit is covered with fuel and drains when the vacuum bleeds off.

I will be back to shop on Friday and will scan the service manual.
Randy - RPM

[FJ1100mjk]

Randy:

The clear tube was held on the centerline of the carb slide bore. According to a comment made by a fellow forum member (I believe DavidR), if measured in this manner, the carbs' incline effect on the measurement is taken out of the picture. Seemed like a valid statement at the time so I ran with it when I did my float level adjustments.

Like I stated in my initial email, I wouldn't be surprised if the carbs were coming back off again.

[SlowOldGuy]

Randy is not saying your measuring technique is bad, the level you chose is bad.  It should be at least 5mm below the gasket surface.

Allow me to calrify what Randy is saying:

Yes, your measurement is correct and does not depend on the angle of the carbs as long as you referenced the center of the float bowl.  However, 3mm is too high.  When the carbs are on the bike, they are tilted forward, causing the fuel level at the front of the float bowl (near the choke air intake port) to be way too high and thus causing fuel to seep out of the choke air port.

DavidR.