both times it was easy as butter (why is butter easy?)  Heard the cap squealing, so I know I didn't screw up the escape vent.  And the tank hasn't crushed, so I know I didn't screw up the intake vent.

heh HEH  He said butter and squealing.
Yeah, screwing up the escape vent isn't for everyone.
....same goes for the intake vent, but the latter is one of the more popular options.

..sorry folks, but someone just had to show why all those "easy boys" are justified, and I'm just the guy for the job. Thanks max' for the assist.

 

And allow me to add: it is much less of a problem to plug up the exhaust vent for several reasons, usually internal pressure will overcome the vent's ability to stay closed, and there are other ports that will provide the venting process as well long before it becomes catastrophic (such as the entire spring loaded fuel cap sealing plate will simply lift- sure it will stink for a bit but it relieves the pressure).

On the other hand, plugging in the intake vent is often catastrophic because that often results in an entire vessel failure, always of course, depending on how long that vent is plugged.

But on a serious note, the most common method by far of fuel tank failure due to vent failure is collapse (the tank caves in). The reason is simple physics; on a fuel injected vehicle, the fuel pump can get quite close to a full vacuum inside the tank which makes for a 14+ PSI differential. It is not possible to build up 14 PSI inside the tank given nothing but gasoline expansion unless some ridiculous event happened such as you fueled the bike in Dead Horse, AK, at -60F, immediately put the bike in a plane and flew it to Death Vally, CA, while it was 125F..... and even them I do not think gasoline has the ability to form that much vapor pressure. But of course I could be wrong and so we better just wait for someone to do this and we will have actual results. 

Brian

heh HEH  He said butter and squealing.
Yeah, screwing up the escape vent isn't for everyone.
....same goes for the intake vent, but the latter is one of the more popular options.

..sorry folks, but someone just had to show why all those "easy boys" are justified, and I'm just the guy for the job. Thanks max' for the assist.

I usually end up filling the bike 2-3 times a week before storing it for the next days ride.  I usually fill it about half way up the fill neck which submerges most of the latch mechanism in gas.  I think that this reduces corrosion or oxidation, but who knows.

I don't think that graphite is the best thing to use to lubricate the mechanism as it will eventually wash into the gas tank.  Marvel Mystery Oil or any light weight oil would be a better solution.  As I said before I think that if you keep the tank above the bottom of the neck that there will be less corrosion or oxidation.

These are just guesses but after 30k on this C14 and 26k on the last c14 I have had little to no problems with the Latch mechanisms.

Nice write up Max!!

Fred
Wa2gzw

Add me to the list of folks that have had a gas cap become almost inoperable.  Read through this thread and thought I'd give cleaning/lubing it a shot.  The pitting wasn't nearly what I thought I'd find, but there was lots of grey "dust".  Cleaned everything with brake fluid and then lubed it with the lock de-icer lubricant I bought a few weeks ago.  Didn't seem to make much difference in its operation.  Sprayed everything down with lithium grease at this point and the latches moved MUCH more freely.

Reassembling: everything WILL fly in every possible direction when trying to get it back together.  Pay close attention to how everything comes apart.  It wasn't hugely difficult, but it likely would have been if I wasn't prepared for it to happen.  Lock works much more easily now, although not quite brand spanky new.  We'll see how long this holds up.  New assemblies are a little over $100 on RMATV.com.  I haven't shopped it elsewhere yet.

Cleaned it with brake fluid?

Cleaned it with brake fluid?

I think he meant brake cleaner
My mechanic friend loves that stuff and uses it a lot.

I like it as well.

I think he meant brake cleaner
My mechanic friend loves that stuff and uses it a lot.

Yep.  Brake cleaner. 

Brain fart...

Think ill be tackling this on Sunday. My tank vent has been screaming at me on warm days for about a year now. Time to shut the bitch up. 

Not long-term yet, but so far, so good.   I have filled the tank twice since.  Both times it was easy as butter (why is butter easy?)  Heard the cap squealing, so I know I didn't screw up the escape vent.  And the tank hasn't crushed, so I know I didn't screw up the intake vent.

OK, now I am concerned.  Twice now I have had the experience of going to fill it with gas and having a near "explosion" of pressure come out of the tank.  I am not sure what causes so much pressure buildup, nor why it wasn't released by the cap.  Worse, it is unpredictable as to if and when it will happen.  I didn't want to post anything until I was sure it wasn't a one-time fluke.  Also not sure what kind of damage, if any, this might cause.

This had never happened before I had to re-assemble the cap.  So this could be an indication that I did, indeed, mess up the reassembly of the little valve stuff in the gas cap.  My issue is that the factory manual has no information or diagram as to how it is supposed to be assembled.  Does anyone know how I can get access to such information?  I would ask if some daring person is able to get photos of everything in-situ, but I am afraid he might end up in a similar predicament

This help... http://www.pbase.com/fredharmon/gascapmod ?

But it sounds (pun intended) like a vent is clogged.  I've never had that happen to my gas cap.

This help... http://www.pbase.com/fredharmon/gascapmod ?

Unfortunately, no.  That is about the latch.  I need info on the mess that is above it.  I am quite sure my latch procedures were all fine (still turns great and love the key pull-out mod).  It was when I went in, snooping around under the black rubber area that I believe things went wrong (and also why I cautioned people about it too).

But it sounds (pun intended) like a vent is clogged.  I've never had that happen to my gas cap.

Although it is possible, that would make for a remarkable coincidence to my having to reassemble the cap (4.5 years no problems, mess with cap and then immediately have random pressure issues). 

Although it is possible, that would make for a remarkable coincidence to my having to reassemble the cap (4.5 years no problems, mess with cap and then immediately have random pressure issues). 

No problems before you messed with it...   Problems after.   Hmmmm

Twice now I have had the experience of going to fill it with gas and having a near "explosion" of pressure come out of the tank.  I am not sure what causes so much pressure buildup, nor why it wasn't released by the cap.

I've only refueled my 2015 once, and that happened to me. Maybe not 'explosion' bad, but way more than normal IMO. Now, all 2015 bikes have CA emissions now, and maybe that's the way they work (unlikely a brand new bike off the truck has such an issue, but always possible). Positive pressure shouldn't be an issue on a CA bike since fumes are routed thru the charcoal canister (that's what it's for). It'd be nice to see a diagram of how exactly the EVAP system works on these bikes. Anyway, I'll have to determine if what I have is positive or negative (vacuum) pressure, since both 'swishhhh' when tank is opened... but are different problems. Wasn't expecting that, so didn't notice which one. Vacuum can collapse a tank. But the good news is positive pressure should force the gas cap spring open before causing damage to the tank (that's what it's for too). Let us know if you find the culprit. Good luck.

One thread talked about a pinched vent hose.

Anyway, I'll have to determine if what I have is positive or negative (vacuum) pressure, since both 'swishhhh' when tank is opened... but are different problems.

No question which direction in my case, because it was way more than a swish/hiss.  It energetically spewed out gases forward, toward the dash (that I could even see), after the cap flew open when I turned the key.  "Explosion" might not be the best word, but both events were orders of magnitude more pressurethan I have experienced on any motorcycle (or any vehicle for that matter).

Buy a new cap and have done with it, Max.  51049-0039 105.00 at Ron Ayers or take it in to the dealer or buy an aftermarket cap for about 1/2 or less. 

Buy a new cap and have done with it, Max.  51049-0039 105.00 at Ron Ayers

I will if I have to, but it is just so annoying that it is probably just one little part not in there right and there is no info anywhere.   I hate spending money for no good reason.

He says as the bike blows up in front of his face...

My gas cap use to squeal like crazy when the weather got hot. At times, I could barely open up the gas cap with all the suction it created.  I took my overly complex gas cap apart and removed a little spring that pressed a plastic valve against air relief valve. I think it's there to prevent gas from coming out if the bike is tipped over, but I'm not sure. Anyways, venting has worked perfectly since, no squealing or excessive suction when opening up the cap. I figured, if the bike crashes or tips over, a small amount of gas on the pavement is going to be the least of my worries. Besides, there's a tip-over sensor that kills the engine, so fire is very unlikely. I got the idea from a forum; I wish I could find it...