Fuel Tank Vacume

[The_Inventor]

So you order a new fuel cap and find out you just wasted another 15.00 because it doesn't breath either. It took me all of 15 seconds to drill a hole and you can't really even tell it's there.

I dont think that drilling a hole in the cap is going to fix a seal that is letting fuel out

 

[steelfan41]

Here are a few pics of the cap. As you can see the seal is in good condition, the springs work as well. There are 4 holes in the bottom and 2 on the sides. My idea was to fill all the holes with RTV and then drill a hose to accommodate a 8-10 inch piece of fuel line to act as the vent and hopefully allow more fuel. My rides are roughly 20 miles each way and I want to be able to make a round trip w/o smelling like an oily rag. One other solution I had thought of was RTVing the underside of the seal, as right now the seal sits above the tank mouth. Would putting say 1/2 inch or 1 inch of RTV under the seal pushing the seal further down the throat fix the cap's leaking problem... Right now I can fill up 1/3 and carry a handy liter of mixed petrol in a gatorade bottle.

 

[The_Inventor]

There are 4 holes in the bottom and 2 on the sides. My idea was to fill all the holes with RTV and then drill a hose to accommodate a 8-10 inch piece of fuel line to act as the vent.

What exactly are you going to hook up that fuel line vent to?

 

[steelfan41]

My thought was about 1 inch or maybe 2 in the hole I drill. Basically like the 2 stroke motorcycles run. I shouldn't (I think) run in to overflow problems. The rest of the line would be unsecured.

 

[The_Inventor]

Where will you drill the hole is what I meant

 

[steelfan41]

Center of cap. =) Insert 1-2 inches of fuel line and add some RTV and see if it works.

 

[w31john]

I think you need a new gas cap or your tank is bent near the seal.

 

[steelfan41]

I think you need a new gas cap or your tank is bent near the seal.

I am trying sealant in the top of the cap above where the seal sits. I know it probably won't work however, I just have to make an easy fix attempt. Where is the best place to get a new cap if that's needed?

Thanks, Walt

 

[RedBaronX]

Yet another problem. Don't they test anything in China to see if it works? My fuel stops flowing after a couple of minutes and I have to loosen the fuel tank cap to let air in and get fuel back in the carb. Are you guys drilling a hole in the cap or something so it'll breath?

I'm using a tank from a Whizzer bike, and the cap doesn't breathe on that, either. I drilled a hole, and because my bike does have to live outside during the months I ride it, I fashioned a rain "cover" out of epoxy putty, which you can kind of see here:

 

[steelfan41]

How big is that tank? I am looking for the biggest tank I can safely mount on the frame.