Is the gas cap supposed to vent?

I have found out that when I ride the fuel stops flowing after a little while. I look down at the fuel filter and it is empty. The tank is creating a vacuum and stopping the fuel. I finally found out that if I open the gas cap for a second the gas flows into the filter. I can run with the gas cap NOT fully latched so that it vents air into the tank, then it runs great.

Is the gas cap supposed to have a vent to keep from building a vacuum in the tank? I don't want to ride with my gas cap open all the time.

yes it has a vent built into the cap area

Yes, it should have a venting action, otherwise when out for a ride, the engine will suffer fuel starvation & possibly run lean. Open up the cap, looking for sealing washers/flaps to allow air to get into the tank. You'll probably have to go to either www.bikebandit.com or www.kawasaki.com for a parts breakdown.

fuel tank cap gasket 11009-1051 $4.98 according to babbits.com anyway

If you take the cap off, then put it upside down on your work area, take out the two Phillips head screws. Then the center section will come apart. there will be two holes and matching groove for the venting.. make sure that they are clear, clean, etc. Pretty simple to clean it, just be careful with those screws, could be pretty stuck, soak then overnight with PB blaster or something. then one the ones I've done I used a hand impact driver with the correct bit. Came out without striping or breaking.

Took the cap apart and the vent goes through the lock. After taking the lock off there was a little 1/32in whole under the edge, beneath the spring loaded seal. I can't believe this little bitty whole has been my whole problem.

Thanks.

if your not gonna ride for a couple days take the cap off put it in a small bowl spray it real good with pb blaster or whatevr penetrating oil you have let it soak a while fill it up with CLR and by morning those screws come out like a genie broke them loose in the middle of the night. did the last couple of nasty rusted unusable caps that way tookk a detail brush brushed it off put the new gasket on looked ans worked like new

Yep sounds like you got it then. It looked to me like a puny little POS design, but it seems to work. Same size vent on a 1100 as your 550. Go figure. Any decent two stroke has a 1/8 line at least, and only 1 carb!

I was expecting a larger hole then that or at least more then one hole (so if one got plugged it would still work).

I also found another negative side to the dredded pod filters today. While my bikes was parked today it rained and I think practically filled the #4 carb with water. Need to design some kind of sheet metal sheild over the top that bends down on the sides to keep rain and cross winds out.

Pod's= fair weather, I do to much varied riding to even consider those.
Factory Air-Box, with a good flowing filter, Best for street/ everyday riding. Now if your racing on a track? Can you get more power from pods or a Custom Air-Box? I bet Air-Box, you can Ram Air a box pretty easy.

Pods=fair weather=bs

If you're really in the mood to play with jetting - try this

www.zrxoa.org/forums/showthread.php?t=226528&page=4

On my GPz after I shut the hot engine down, I will actually hear the fuel cap vent emit a very soft "whistle" type venting sound .