Gas tank. Not the ethanol expanding issue; though an expanding issue nonetheless

[DDDuc]

New to the forum (been hanging out in the background for a while).  Anyways, I just picked up an 09 Monster 1100s and I have a couple of (unrelated) questions:

First:  My gas tank seems to lack any sort of pressure escape.  For example, I went riding a few weeks ago and stopped at a gas station to fill up.  When I opened the gas tank, it sucked a good amount of air in (as if when the bike consumed fuel no air replaced the lost fuel in the tank).  Just a few days ago, I took the bike out of a cool garage and rode around for a bit.  When I went to the gas station to fill up, and opened the cap, a bunch of air rushed out; so much so that I could physically see the plastic side covers on the gas tank "deflate".  this was probably due to the expansion of gas vapors due to the increase in air temperature.  I purchased the bike new and have not removed the charcol canister.  Is this normal?  Any suggestions?

Second:  Does anybody know what size allen wrench I need to remove the oil screen?  I don't have any that large.

Thanks in advance for any responses.

[Heath]

Might want to check for a pinched hose.  If someone lifted the tank and wasn't paying attention to the hose that lets it vent it could of got pinched.  I did that to mine once.

[battlecry]

It's a 14mm on mine.  I believe it may be the same on the newer Ducs.

Buy one and display it with pride.  If anybody asks, make up a story involving Alfas or Volkswagens.

[chris1044]

Correct on the 14mm allen key...

[Slide Panda]

Might want to check for a pinched hose. 

+1 That's exactly why happens when a breather hose has been pinched off or blocked.

[thought]

hmmm... my bike has been making a vacuum noise when i've been topping it off recently too.  i just thought it was like how cars have that issue when you open the gas cap.  no expansion though.

i'll go check the routing this weekend too.

[DDDuc]

Thanks for all of the responses.  I think a pinched hose makes sense . . . looks like I'll be digging into this bike sooner than I expected!

[redxblack]

Glad for this thread. I thought it was supposed to as well, like a car.

[thought]

Glad for this thread. I thought it was supposed to as well, like a car.

might want to take a look at this thread too...

http://www.ducatimonsterforum.org/index.php?topic=49014.0

seems that the vacuum sound is something that's happening alot and the breather hose can collapse under engine heat.