'94 that sat for a few years leaking from carb fuel connection

I have a '94 VFR750F that has been sitting non-op'd for a few years. I had drained the fuel from the system and disconnected the fuel lines way back when I had to non-op it.

I got it running yesterday, and it was very hard to start. I can't say for certain that all 4 cylinders were firing because as soon as it was able sustain itself I smelled and immediately discovered fuel dripping from the carbs.

I removed the entire airbox assembly so I could figure out exactly where the leak was coming from, and it was the header in this picture.



I verified this by completely drying everything and then starting the bike and watching fuel slowly seep out. I could only find fuel coming from the connection at the carb for cylinder 2.

I'm really not a carb guy. I've successfully installed jet kits and adjusted mixture screws, but I've really no idea how to troubleshoot carbs. Is this just a bad o-ring, or is it indicative of something worse?

 

Could be an O-ring, if you can get to fuel line by the carbs and slip it off, try running some lacquer thinner through the carb for about an 1/2 hour, then drain and refill with gas. Lacquer thinner will swell the rubber parts. Better than disassembling!

 

Thanks for the tip. I'm assuming that requires removing the carbs from the bike? They are still installed.

Also, is that a permanent fix or temporary?

And just to be clear, the leak is most likely just an o-ring? Not something inside a carb causing pressure to build in the line and then the fuel to go past the weakest seal?

 

If it was the needle float valve, then gas would be coming out of overflow hole.

My tip was meant to be done on the bike. I think once o-ring swells, it will keep sealing.

Might have to drain the #2 bowl to let lacquer thinner flow through. (small brass screw at the bottom)

 

Any bike just emerging from long storage is more than 50% likely to drip fuel initially from O-rings that shrink over time and dry up. The cure is often just to let the carbs sit full of fuel for a few hours or a day, after which seals will likely swell up most conveniently, cuz fixin it up all proper-like with new rings is a Royal PIA and takes alot of time.

 

squirrelman is right, as that cylinder did stop leaking. However, now there is a leak/seepage from cylinder 4 that doesn't seem to be going away. The bike has been fueled for a week. I even started it every night just to be sure the pipe had fuel in it.

In looking at the carbs, it really isn't clear to me how I might run lacquer thinner through the carb without dumping it into the intake. Any tips on that?

Also, I'm looking at possibly just replacing all of the o-rings. How much trouble am I really getting myself into with that?

I have to say, I'm really glad fuel injection came along, because these later-model carbureted bikes seem to have had some pretty complex systems, not that the V-4 configuration makes things any easier.

 

Carbs are simple if you've done just a little reading; it's Fi that's complex, with all its computers and multiple sensors and regulators and dozens of plugs, relays, pump, etc., all the horrible things that can't be fixed with wrenches and screwdrivers.The entire carb service section in the factory manual runs to about 12 pages, while the FI service section runs to about 40-50 pages or more ! So what's so complex about carbs since they only mix air and fuel in controlled amounts without the excessive and unnecessary use of computers or sensors or electricity or special non-stock programs to improve FI performance or relays !! ?? Given the difference in the number of elements that might fail in FI vs. carbs, carbs win for reliability (if they're kept clean). V-4 carbs are not really different from I-4 carbs, nothing unusual.

Replacing the crossover tubes' O-rings is tedious work, takes alot of time and proper tools. Best done ONLY IF they're leaking imo. Bowl O-rings are ez.

I know it's an unpopular, idiosyncratic opinion, but............

 

+1 for rebuilding carbs - you do not want to risk failrure on the road in the middle of nowhere, and with bike sitting for so long, all the seals and o-rings have hardened and will not seal for much longer.

Rebuilding is nothing more than a good clean and re-assembly with all new seals, and shop manual should be sufficient to finish the job.