gasoline vomitorium

[DgM]

Riding along, everything aok, engine starts running on one cylinder, coughs, stops.  Left carb pouring gasoline on exhaust pipes, ground, right carb no leaks.  Tap carb with gloved hand, gas stops pouring.  Wait a minute, bike starts up, runs fine, ride home expecting gas geyser, no leaking.  Anyone else experience this?  What causes this and how to fix?  Help!

[donbmw]

float needle stuck open could have some trash under seat of needle.

Don

[montmil]

Time to clean out the float bowl needle valve seat and check the condition of the carb float... both sides. And here you thought you'd get to ride on Saturday.      Not a tough job. Glad you didn't roast your weiner on a blazing saddle.

[Yikes]

Check the condition of your fuel lines.  They may look fine on the outside but be cracked on the inside and dropping little bits of junk that makes keeps those valves from closing.  A foot or two of new fuel line is a really cheap fix.  It may also be a good time to replace those gaskets between the carb body and float bowls.

[Rob Valdez 79 R65]

I replace my fuel line every 2 or 3 years for this reason alone.

I had mine leak on me once, in 2000.  Never since.


You should also take the time to empty the fuel tank and remove the petcock to examine the screen that may be inside.
My petcock also has a second, smaller screen at the bottom, where the hose slips on.

Do you know when the float needles were last replaced?
They have a rubber seal on the tip, and that can harden over time and make it harder to seal.

If the floats are old, they may be starting to absorb gas, and would be heavy and not work so well.

[DgM]

Thanks for the help.  Looks like a weekend with the carbs.  Can work be accomplished while carbs are on bike or must they be removed?  Super drag, as I just finished install of brembo caliper, pads, disc, splitter, lines, new master cylinder...braking more progressive, smoother, a bit more powerful.  Thanks for the parts Montmil!

[Rob Valdez 79 R65]

I aways liked that fairing (BCW).  That is a real pretty bike you have there.

Don't worry about the carbs, after you fix them, something else will likely call for your attention!


I am pretty sure you can remove the pin to drop the floats with the carbs mounted on the bike, but it would be a whole lot easier to do on the bench.

The pin will only move one direction, so examine it closely to determine which way to drift it.

Only work on one carb at a time, so if you forget how something goes back together, you have the other to refer to.

[not-so-fast-ed]

Lovely, Classic Look!  Really special.

Ed    

[DgM]

Thanks for compliment on bike.  It's a sweetheart...when it runs!  Started it up, engine as usual caught, idled with choke on, warmed up, turned choke off, idled well, no leaks, then began running rough (like drowning in fuel), gasoline vomitorium once again.  Removed float bowl from overflowing carb.  Inside clean as a whistle.  Needle riding on float bowl bracket moves with no sticking, no effort.  Gasket between float bowl intact cork, thin.  Floats didn't seem fuel logged, white/tan plastic.  Reinstalled float bowl, turned on gas tap, gasoline everywhere again.  Does this indicate floats filling with gasoline, sinking, float bowl overflowing?  Would a too thin gasket between float bowl and body cause overflowing?  Or am I going to have to remove carbs and take apart?

[Rob Valdez 79 R65]

Pull the fuel lines off the carbs, and plug them with a couple of golf tees, or something similar.

Turn on the gas.

Make sure the fuel lines are not leaking.

[DgM]

Removed fuel lines, plugged with golf tee, turned on gas.  No leaks.  Hooked up fuel line, turned on gas, so much gas spewing it seems to be coming from every seam of carb  Turned off gas.  Pulled carb, throat not as clean as inside float bowl, not gummed up.  Removed float bowl, checked float and needle again - float not soaked, float needle moving freely - replaced float bowl, reinstalled carb, turned on gas, no leak, no spewing.  What gives???  What can be screwing up inside to cause this?  Haunted carb?

[Rob Valdez 79 R65]

It could be dirt in the fuel, getting between the needle and the seat.

You need to empty the fuel tank and remove the petcock and see what comes out.  See if you have any filters on the petcock at all.

Some folks like inline filters.  I've never found the need, myself.

My petcock has two filters.  A big one slips over the two tubes that allow the gas into the petcock.
The small filter is on the bottom of the petcock, just above where the hose slips on.

If you have crap in the tank, and no filters, that would explain a lot.

[DgM]

I have an inline filter, gas viewed in filter and in float bowl free of grit, dirt, muck.  The leak seems to be a carb internal issue, as if floats are sinking and letting gusher of gas into carb which then overflows.  Yet floats are light and needle isn't sticking.  A conundrum.  This issue first came up only after riding, parking bike for a short time and restarting, wondered if heat from engine was cooking fuel lines, now spewing with cold engine.  Before big spew, engine runs rough, then dies as gasoline drips drips drips.  What could have come loose or get clogged?  Can float needle wear out/break/fall apart?

[Rob Valdez 79 R65]

Have you replaced the lines, floats, etc?  I mean, do you know how old these parts are?  Baselines are good.

Where do you live?  Is there weird stuff in the gas?

[donbmw]

I have had a fuel bowl with some corroision start weeping fuel that looked like it was leaking out the overflow.

Don