Quote:
Originally Posted by spooph
Doesn't the pregen have an overflow tube like the new gen though? Shouldn't it be able to breath out of that as well?
Yes, good recommendation for the test, just wondering for my own edification.
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That's a good question for someone who knows about these bikes. =)
It's a huge problem on the VN750 (they even gave it a name - Phantom Out Of Gas Syndrome, or POOGS) and pretty common on the EX500. I've seen posts about the vent here before, so I'm just assuming it's similar.
On the 500, there's an overflow drain tube that's connected to the area around the fill hole. But the air in the tank still has to go through the vent system to breathe out to that area.
The tank has to have some sort of vent. If air can't get in to replace the fuel that's leaving, it'll vacuum-lock and the fuel will stop flowing. They use a few rubber discs in the vent so that it's not just completely open to the atmosphere, which would allow for faster evaporation, contamination, and more spillage if it tipped over. Over time those rubber discs get hard and stop working properly, leading to that vent not actually venting.