Fuel leaking from carb hose on 85 FJ1100

[Gearbox Paul]

New fuel supply and carb vent hoses ordered, as well as petcock rebuild kit.  I flushed fuel tank and checked for rust/debris - none found, looks really clean as far as I can see.  I haven't checked my crankcase oil for fuel contamination yet but I will. 

Waiting for parts to arrive and will report back. 

[Gearbox Paul]

Update

Parts finally arrived and I got some time to look into this again.  Installed new choke vent lines on all carbs.  Installed 2 new float bowl vent hoses as well.  Replaced fuel line from petcock to carbs with new.  Routed as per diagram and removed fuel filter that previous owner had added.  Installed new diaphragm and spring in petcock.  Petcock now holds closed unless vacuum is applied.  Tank was flushed and is free of debris. 

Put everything back together and started bike.  Bike started up nicely but fuel started leaking badly out of choke vent for carb #1 and #4, maybe 2 or 3 too - it was hard to tell, fuel was gushing out, had to stop bike immediately.  Fuel stopped leaking a couple minutes after I stopped the bike - so petcolk seems to be doing its job.  So I guess my next step is to clean and rebuild the carbs. 

It seems very coincidental that I would have a bad needle o-ring or stuck float on two (may more than two) carbs at the same time.  I'm wondering if I missed something when I put it back together.  One thing I wasn't sure about is the hose on bottom of the gas tank.  I suspect this is a vent hose for the tank?  Anyhow, I couldn't remember if it was connected to anything so I routed it down the back of the engine along with the carb vent hoses. 

[Pat Conlon]

My money is on dry leaking o rings on the float needle seats.

Very common.

[Gearbox Paul]

Update #2.  Not as much progress as I would like.

Installed new float needles, needle seats and o-rings in carbs 1-3.  For carb #4, couldn't get float pin out without breaking something, so that carb did not get a new needle and seat. Cleaned rest of carbs and found very little debris or varnish in there.  Floats looked high but left as is.  Put back together and tested on bench to see if carbs would overflow.  Carbs #1 and 2 immediately overflowed.  Took these apart and noticed the floats from the rebuild kit had a different orifice size.  I don't think that's critical but I decided to put the old seats and needles back into carbs 1-3 with new o-rings.  I also adjusted the float level lower on carbs 1-2.  Put back together and bench tested and it did not leak.  Installed carbs on bike with a temporary gas tank.  Started bike up and it ran fine.

I then replaced the engine oil as it has been contaminated with some fuel.  Tested again with a temporary gas tank and carb #3 overflowed immediately.  Seemed to seal itself, so I started up the bike and again it ran fine, and carbs did not overflow.  Ran bike out of fuel and drained carbs as I will be away for a while and bike will sit for several months. 

When I'm back (in the New Year), I'll look into those float levels again and adjust lower as they are still higher than spec.  And I'll find a new float and pin for carb #4 so that I can cut out the one that's stuck in there.  Lastly, the gas tank petcock, that I replaced the diaphragm on, was holding for a while but started leaking again.  I'll need to dig into this one again in the spring.  All in all, quite frustrating.   

[Pat Conlon]

Call it a day with the oem 40 year old petcock and buy a new one.

There's other things in life to worry about....those wonky vacuum petcocks ain't one of them.