Gas Cap Blues....

[Vince Lupo]

I'm very excited about this little project -- thanks for all the advice, everyone!

The metal around the filler is in fact bare metal, but the gas managed to get under the seam between the paint and the bare metal. As mentioned earlier, the Krazy Glue solution seems to have fixed that issue, and we'll see if this vent arrangement might help alleviate the wet gasket situation -- anyways, it's worth a try!

As far as routing the hose, I'll have to look more closely at the bike and see what would look unobtrusive yet functional. I was looking in Hugo Wilson's "The Ultimate Motor Cycle Book", and under the 'racing' section on page 147, there's a photo of Kevin Schwantz's Suzuki, and the hose on that one just seems to sit inside the fairing behind the clear windscreen. I was a bit concerned myself regarding the hose going underneath the tank....don't want anything going BOOM!

So why would dirt bikes and race bikes have this type of cap/hose, but street bikes don't?

[teazer]

Vince,
I didn't design either type of bikes, but I'd speculate that race bikes of any type suck gas out much faster than a street bike and need a larger hole to be sure that enough air gets back in. Bigger hole = more propensity to leak.

LM,
Good point about the nature of modern gas which is almost as effective as paint stripper.

[Vince Lupo]

Well I actually managed to tear myself away from the computer last night and actually have a look at my bike. The only spot I can find that's in front of the gas tank and away from any hot surfaces would be the front right tank mount. I could probably loop the tube around it and it wouldn't be affected by any steering issues. I'll have to discuss it in more detail with my mechanic to come up with a good location (I still do like the idea of routing it under the tank though).

I did, however, ask a race bike friend of mine about it today (he races regularly at Summit Point and Miller Motorsports). He said that as long as the tube is out of the way of the breeze/wind, it doesn't really matter where it goes -- if any breeze/wind is allowed to create a vacuum, it could suck gas right out of the tank (one reason why the tubes are normally clear - so you can see if any gas does happen to get in there). I guess that's one reason why race bikes normally have the tube just sitting inside the fairing, and probably why you guys are suggesting the one-way valve. So based on this info, it could run underneath the tank as well.

Who knows, this whole endeavour might not even solve the problem, but I'm willing to look into it -- what the heck!

[Vince Lupo]

So I received the new gas cap a couple of days ago, and it looks really good and fits just fine (it's pretty well like the SuperHawk cap, but with the nipple on the top). I also found a Sunline 'one-way' inline vent on eBay, so hopefully that will help things out too.

I'm going to try clear fuel line instead of the black tube that was provided with the cap -- I think it will look better, and it will enable me to see if there is any fuel being sucked out of the tank. Hopefully I should have this rigged up by the end of next week.

[burvis]

I read through this thread trying to find an answer to my own problem. My gas cap is not venting, and danged if I can find any vent hole on the underside of my gas cap at all. I was getting some very expert help with my clutch earlier (thanks LM!) and went out for a ride only to be stymied by a bad gas cap. Here are some pics with the rubber gasket removed. Where should this vent hole be? Is this the wrong cap for my bike perhaps? I'm showing the underside of the cap from 12 oclock, 3 oclock, 6 oclock and 9 oclock. Oh, and I'm taking this opportunity to clean this cap up a bit with some steel wool...

[Vince Lupo]

The closest thing I can see is in photo #2 on the right inside edge of the cap, as it appears that there's a hole there. The vent hole is a teeny-tiny hole, and you should be able to see it with the gasket on (the gasket does not cover the hole).

As far as my 'new' cap goes, I have all the elements together now (cap, clear tubing, tube clip, one-way vent), and hopefully it should be on soon. I just need to figure out the routing/location of the tube.

[burvis]

you're right it looks like a hole... but it ain't it's just a speck. So that's where the hole is supposed to be? Just inside the lip like that? I promise this cap doesn't have them. So it is possible to split the two halves of the cap? maybe I should try that and drill some vent holes in the inner cap?