Gas leak from carbs? (fixed)
- The549
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Gas leak from carbs? (fixed)
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.
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.
Last edited by The549 on Tue Feb 27, 2007 8:47 pm, edited 1 time in total.
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.
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.
- Sev
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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.
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.
Of course I'm generalizing from a single example here, but everyone does that. At least I do.
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- KarateChick
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Wood! Yikes...kaboom!The549 wrote:Ahaha![]()
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.![]()
Fixed. Thanks!

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.
Ya right,
there are only 2 kinds of bikes: It's a Ninja... look that one's a Harley... oh there's a Ninja... Harley...Ninja...
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prime
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
)
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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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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