DocShadow wrote:
rollover valve

For the life of me I don't see how that would relate to 'puking'.

What you describe is a vacuum in the tank (that's why they implode). In that case the direction of flow would be the gas getting sucked out of the carb into the tank not forced out of the carb.

Doc
Doc if you have an electric fuel pump sucking the gas out and putting pressure towards the carb where is the pressure going to go?? It can't push back towards the tank! I don't know about a roll over valve but I can tell you that if you put pressure into your tank it's going to follow the path of least resistence which would be to push the pressure out through the carb. What's so hard to understand?? I'm not here to argue problems that have occured with R*'s. I had a problem just like what this person was discribing and I gave him an answer of what I found to be the problem with my R*. Take it for what's it's worth or ignore it. I don't really care. I'm trying to understand why you would post a comment questioning what happened to my bike?? Do you think that I post here with just mere guesses??
Danny

First you need to take a deep breath ... I asked a valid question, not an attack on your post.

The R* gas cap is not vented so the purpose of the vent tube is to provide an inlet for air as the gas is sucked out by the pump. The purpose of the rollover valve is to prevent gas from coming out of the tank if the bike falls over ... it's essentially a one way valve letting air into the tank but no gas out. Under some conditions the valve sticks closed and air cannot get into the tank as the gas is emptied by the fuel pump. This result in a partial vacuum forming inside the tank and under extreme situations it causes the tank to implode ... such as you witnessed.

Nature abhors a vacuum thus a liquid or gas outside the vacuum will flow towards this area of lower pressure in order to normalize the pressure (the "whoosh" sound you hear when you take the gas cap off) ... in other words the gas in the fuel line would tend to flow towards the tank, away from the carb ... it would not pressurize the carb.

Puking is a result of gas being expelled from the carb due to excessive pressure within the float bowl. Numerous people have speculated that it's due to the gas heating up and pressurizing the carb or possibly due to a faulty pump pressurizing the carb.

Be it as it may, my question was, and still is, how is a partial vacuum in the tank was related to puking of the carb?

The tank is under vacuum ... it cannot pressurize the carb.

Puking normally results in a 'hard to start' situation. A stuck rollover valve could also be a cause of hard starting. The partial pressure inside the tank becomes so great that the fuel pump cannot overcome this pressure and will not be able to replenish the float bowl, starving the carb. But again even though the symptoms are the same, the cause is different .... one produces a flood carb, the other a dry carb.

Doc

Well Doc I took a deep breath and I have to say you must have the right answer! I guess I can't explain what happened to my bike 9 years ago when I had the same exact problem as xludan described. I know what I did to try and get by, like turning off the gas before I shut it down and leaving the petcock closed till I got the bike started but it still never completely solved the problem until after the implosion of the tank and taking it back to the dealer. I have told xludan what I was told by the mechanic at the dealer ship and it being a stuck or defective valve. Once this valve was replaced I never experianced the flooding and hard starting after that point. That is 9 years & over 68,000 miles later. So again I guess your answer is the right one and I don't know what I'm talking about. And when you tell me that your not attacking my post then why are you still arguing the point I made and going to the effort of trying to prove that it's impossible what I said happened??

Oh and Doc let me ask you another question. If the fuel pump sucks the gas out of the tank would that not mean that it has to push it to the carb? Most electric fuel pumps are placed close to the tank as they push the pressure to the carb. Mechanical pumps pull that is why they are on the engine. No matter what you say if you block the tank from getting air and you have a pump that is pulling gas and pushing it towards the carb that would cause pressure to the carb.

I to had the the puking syndrome, Vented the cap and have ridden over 2000 miles in the Florida heat with no puking and no hard starting.Was in the 90's all last week with No problems.... justmy02cents

Thanks for the suggestions all. I will try venting the gas cap and post my results.

Midnight1700 wrote:
My 07 R* has also had this same problem. What I've been doing is shutting of the fuel about 1/4 mile before I stop. It helps burn some of the fuel in the carb and seems to help with the puking problem. At least it seems to work for me.

Ya, this is what I do too, and always shut the fuel off. It can be a vapour lock from the heat. I will sometimes open the gas tank with the fuel on and it seems to help.

So far I have only had mine puke one time. It is a 2006. It had less than 200 miles on it at the time it happened.

Float bowl level is just a tad too high. Since the carb sits between the jugs it gets very hot and at shutdown of bike the gas is boiling over in the carb, hence, gas comes out the overflow tube. In some cases it can cause the float to stick, and keeps the float needle valve open allowing the pump to pump even more gas into the bowl. Even to the point of such an overflow it comes up thru the main jet and floods the engine, hence the hard start. And add to the problem, if you are running too lean, your engine will be running even hotter, making it easier for boil over. I've never had to shut the petcock with either the stock carb nor the 42hsr I'm running now. Shutting the petcock only gets rid of the symptoms, does nothing to cure the problem.

Erbman02 wrote:
Float bowl level is just a tad too high. Since the carb sits between the jugs it gets very hot and at shutdown of bike the gas is boiling over in the carb, hence, gas comes out the overflow tube. In some cases it can cause the float to stick, and keeps the float needle valve open allowing the pump to pump even more gas into the bowl. Even to the point of such an overflow it comes up thru the main jet and floods the engine, hence the hard start. And add to the problem, if you are running too lean, your engine will be running even hotter, making it easier for boil over. I've never had to shut the petcock with either the stock carb nor the 42hsr I'm running now. Shutting the petcock only gets rid of the symptoms, does nothing to cure the problem.Can I ask what your float level was set at on the stock carb,if you know?