1986 VFR750F fuel leakage while running

Looking for some advice:

I have an '86 RC24 (VFR 750F)

Due to busy things in life, and the K100RS closer to the garage door, I've let the bike sit for the past 3 years.

Feeling very iritated with myself, I've made a pledge to get it back on the road this year. New battery bought, some general look over, etc.

Upon starting to crank over and catch, an EXCESSIVE amount of fuel started pouring out from under the tank. I shut it down and began cleanup, vent the garage etc.

Did some more looking today:

When cranking the engine, fuel starts to pour from a tube that is attatched to the right rear carb. It appears as if it's a vent or similar. It's contained in a securing ring, and looks quite factory.

I had originally presumed it was stuck floats from sitting so long, but nothing comes out the vents on the bottom of each carb, seems to be a very large flow from this one tube. My manual has not been much help I'm afraid.

Anyone know what this tube does and how it functions?

Thanks in advance!

-I

 

I just sold my '86 750 last fall after owning it for more than 10 years. Every winter, I would store it dry in the basement. Every spring when I pulled it out and put gas in it, it would leak fuel from the carbs after putting gas in it for the first time. The o-rings in the carb are known to shrink / dry up and once you re-add fuel, it takes up upwards of a day for the o-rings to swell back their normal dimensions. Does this scenario match what you're experiencing? Did you just put fuel in it after 3 years and just try to start it? If so, let it sit for a day and see if it still leaks fuel.

 

First I don't have one of these, but I have had several 3 or 4 carb bikes that for one reason or another wind up sitting for a while. It likely is a vent. I am betting it came out in the right rear because that's the first place it wasn't gummed up that it could escape.
Did you get fuel coming out of any of the bowls? If not, you probably on the right track with float bowls or needle valves stuck closed.

 

It is from the rubber hose attatched to the right rear carb, and when the fuel pump is running. (Cranking, running)

Doesn't seem to present itself like the ole KZ stuck float situation.

 

More research indicated this may be the vent tube, and all carbs are linked to it.

Back to the stuck float scenario?

 

Was the bike stored or sitting up with the carbs dry (i.e. drained before storage) or wet? If wet then the fuel has turned to varnish and a carb removal and cleaning will be necessary--no magic chemicals exist that will do the job...

 

Foolishly it was upright with tank and carbs wet. It was never the intention to store the bike, just got busy with the other bikes, the car etc etc.

I know I know.........

It does sound like floats stuck does it? This vent tube manifolds to all the carbs?

 

The inlet needles are stuck open and won't shut off--the fuel pump runs and fills the bowls up and keeps running as fuel runs up above the float chamber into the vent. Lots of fuel in there. The bowl drain screw ports are clogged also, that is why no fuel is coming out the drains.

Better check you oil level for "extra" oil, i.e. fuel has washed down the cylinders into the crankcase. Check, clean and repair or replace: Fuel tank, hoses and lines, fuel pump, carbs, crankcase oil, etc.

 

+1 kennybobby Everything is gummed up in there and or crap from old rubber hoses is in carbs. You can try removing the screws from the bowls and gently inserting something to break up the varnish and crud to get some flow, but the end result is likely going to be the same; pull the carbs and go thru them or send them off somewhere, replace the rubbers, and change the oil.

 

Ok;

I've got all the top bits off (tank, lines etc).

I have access to the carbs now, and I have what I think is everything loose. The feel of the carbs is very tight. Is there a bracket or similar that I'm missing? Could it be that the rubbers are just hard enough that it feels like it's still bolted?

The ole Inline KZ did not put up this much fight. Just want to make sure I'm on the right path before I damage somethign else.

Thanks!

 

Loosen the clamps on both ends of the rubber insulator boots, apply heat from a heat gun or hair drier and gently pull the carbs off. If they haven't been off in a long time, those boots can get pretty stuck. You might have to try rotating them with a pair of channel lock plyers...

If the insulator boots are original, you might want to get a set of new ones before you try reinstalling the carbs.

 

You can pry carefully if you need to.

Them bitches don't just jump into your hands; you need to wrestle them off, working from the rear and rocking and pulling and lifting until your brow sweats for awhile and your mouth gets dry.

Let the bike sit in the hot sun for a couple hours to soften up the boots, and put some new ones on order if they're cracked or hardened.