Getting petrol and air into a tank the lightest way?

[gavinnz]

Ok... another brain storming session for the creative thinkers out their....

You have a roadgoing motorcycle fuel tank to be made of carbon fibre. You need to get petrol in and air in and petrol out. What are the lightest weight ways of doing that?

"Petrol in" requires a hole big enough for a gas staion pump nossel (unless you carried a small plastic funnel with you).

Needs to not leak petrol out in use.
Does it need to be a cap that screws on or could it be a clip on cover of some type?

Air must be able to pass into the tank when in use to not create a vaccum in the tank. How do the best motocross bikes do it?

Petrol must pass out the tank to the carb.
Simple pipe with an in line fuel tap.

Any outside the box ideas anyone??

Regards
Gavin

[hmmmnz]

get a pit bike tank off trade me for a few bucks and cut the top of the tank off and use the threaded part and the cap,
and then build the carbon fibre around the part that you have cut from the pitbike tank

as for the drain for the fuel, use the pit bike parts for that as well

[CookMySock]

Just use a hole. Holes weigh nothing!

For the filler I'd be tempted to cut up a gas tank and bog together what you wanted it to look like, then take a mold off that and make up an ultralight part off of it.

For the outlet I'd just use some thin-walled alloy tube.

Steve

[Hitcher]

Get it really hot, as gas is much lighter than liquid.

[imdying]

Lightest? Get a vented plastic fuel cap to allow petrol and air in, and mould the male threading into the top of the tank. Outlet, too many ways to do it, just pick one you like.

[AllanB]

As above for inlet - plastic cap. Air in - Bunnings/Placemakers for a length of plastic hose and glue it into a hole in the plastic cap. Run the other end into a hole in the top nut on the steering stem - hole in nut = less weight too!


Outlet - I suspect there are plastic fuel taps available out there too!

A thought:
Do you need to treat the inside of a carbon fiber tank with anything to avoid the fuel eating at the resin? If so this may be weighty and a alloy tank may end up lighter.

[imdying]

Do you need to treat the inside of a carbon fiber tank with anything to avoid the fuel eating at the resin? If so this may be weighty and a alloy tank may end up lighter.

VER was designed for chemical tanks, it's not a problem.

[motorbyclist]

How do the best motocross bikes do it?

every offroad vehicle I'v ever seen has a plastic screw on cap with a breather tube (tube fitted with with a one-way valve) and the tube generally went into the steering head somewhere.

You can buy blingy anodised caps with short breather lines from most shops (cycletreads has a whole section devoted to useless dirtbike bling)