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Gas leak from carbs? (fixed)

Posted: Mon Feb 12, 2007 2:42 pm
by The549
So along with a new bike to ride for the first time, $800 out of my pocket and a set of tools, I got my first new (to me) bike problem.

I think this just started happening yesterday in the parking lot. I noticed a little leak. I didn't think much of it and assumed it was oil at first, but found out upon smelling that it was gas. It leaks out of the housing (in between air box and carbs) drain tube.

I think I left the choke on, but could this cause the bike to leak that easily? We're talking at least a gallon leaked; it's flowing all the way through from the tank.

The previous owner cleaned the carbs out 4 months ago, so hopefully he put them together correctly.

Lastly, how do I know when the bike is safe to start up? There was gas in the air box and housing.

ANY help appreciated.

Posted: Mon Feb 12, 2007 2:52 pm
by The549
Oh yes, the pics. The leak comes out of the hose the arrow points to.

Image

Image

Posted: Mon Feb 12, 2007 3:07 pm
by Ian522
If you have a vacuum-type petcock (my old yamaha was) you may have accidently left it in the PRI (prime) position when you last parked the bike which would allow the gas to flow freely into the carbs and overflow everywhere.

Or maybe you have a stuck float in the carbs.

Before attempting to start it make sure the gas didnt leak into the crankcase, which would dilute the oil.

Posted: Mon Feb 12, 2007 3:27 pm
by The549
Yes, I did leave it on pri.

Tell me if this is what I should do:
Wait a bit, smell the oil, run it, then leave the pet on "ON" or "RES" (which one?), and see if it leaks still (which would mean a stuck float).

Thanks!

Posted: Mon Feb 12, 2007 3:45 pm
by The549
Ahaha :lol:

Yes, so what are these newfangled "vacuum petcock" things anyways? Back in my day, we used to make gas tanks out of wood!

I thought pri was primary. So there's no "off" is there?

Rarely do I feel this mentally challenged. :frusty:

Fixed. Thanks!

Posted: Mon Feb 12, 2007 4:20 pm
by Sev
Pri is prime which basically just dumps fuel into the system unabated.

You might consider an oil change now that you've discovered the problem, getting fuel, especially large quantities mixed into the oil can cause problems.

Posted: Mon Feb 12, 2007 6:51 pm
by KarateChick
The549 wrote:Ahaha :lol:

Yes, so what are these newfangled "vacuum petcock" things anyways? Back in my day, we used to make gas tanks out of wood!

I thought pri was primary. So there's no "off" is there?

Rarely do I feel this mentally challenged. :frusty:

Fixed. Thanks!
Wood! Yikes...kaboom! :laughing:

There is no "off", just On, Prime and Reserve. When you start your bike, there's a little air/vacuum hose attached to the petcock that starts up too to draw in fuel and this shuts off as soon as your bike's shut off, so you just would usually leave it in the On position... no need to switch it to an Off setting.

prime

Posted: Fri Feb 16, 2007 2:55 pm
by honda750
the reason for the prime is that when the bike has sat long enough the fuel can evaporate out of the flat bowls in the carbs. The prime allows the gas to flow down into there, but you don't want it to fill the float bowls and keep going, so if you need prime you only want to leave it on max 1 min. any more and you'll just flood the system (before i learned this i actually had gas rolling ouf the exhaust :laughing: )
Res is reserve. There is a part in your tank thats probably half a gallon that doesn't get used at all. When you run out of gas you switch to Res and it goes to the reserved portion of the tank. (You then have to put it to prime for a couple seconds to get it flowing again)
The ON is what you're going to leave it on normally... This way it's only brought into the engine when there's a vacuum

Now for the vacuum part...There is a hose that goes from your petcock to the top of the engine. This is so that whenever the engine is running the vacuum from the engine opens the valve and lets the gas flow.

good luck...those yamahas are keepers :)
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