Oil tank sub as spare gas tank?

Gasoline wont break down the plastic that the oil tank is made of? I know only certain kind of poly carbonates can stand up to gasoline. I would just be nervous that it would break down and mix with the fuel and do alot of internal damage to pretty much every piece of the engine. Great idea though i would love to have an extra half gallon. especially after i hit my reserve and im like ehh it'll be good for a little longer than i forget and its like wahhhh.....brppp.. uh oh?? I wonder how to find out the type of pc the tank is made and check to see what reacts with it?
 
Hi people
I was just sitting thinking where I could fit an extra tank. Brilliant idea !!!!
Instead of having taps and tee's why not jut run it into the tank cap breather like the old header tanks used to work it should drain it as the main tank level drops?
G
 
Hi people
I was just sitting thinking where I could fit an extra tank. Brilliant idea !!!!
Instead of having taps and tee's why not jut run it into the tank cap breather like the old header tanks used to work it should drain it as the main tank level drops?
G

its called a Vent Tube for a reason. it only allows pressure out. if u flip the take upside down, nothing comes out. thats y, and cause it would only drip into there very slowly.
 
I always thought that the vent tube was to allow the tank to maintain atmospheric pressure, and save a partial vaccuum from hindering the fuel supply to the carby.
 
its called a Vent Tube for a reason. it only allows pressure out. if u flip the take upside down, nothing comes out. thats y, and cause it would only drip into there very slowly.

I have heard that it is a one way valve, and I know its function is to allow air into the tank as the fluid level drops.

So if you invert the tank, then it stands to reason that if it is one way, it will seal.

You said that it only allows pressure out.:-/

Aggh, I see the reason for the confusion, you mistyped the word out, it should have been in.:D
 
I have heard that it is a one way valve, and I know its function is to allow air into the tank as the fluid level drops.

So if you invert the tank, then it stands to reason that if it is one way, it will seal.

You said that it only allows pressure out.:-/

Aggh, I see the reason for the confusion, you mistyped the word out, it should have been in.:D

u saying my 15 years is nothing to ur 68???? hmmmmm.... :p yea thats rite i can get u :D lol

no i meant it allows air to come out, but its only very little. so if u tried to pur gas in, it will only drip into it. cause of how small it is.
 
I run a rear tank on my bike:

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With a shut off valve (see the little red thing):

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This photo had me wondering what the little grenade pin was for, but this explains it:

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I am running the engine with the main tank off, just on the rear tank to get easy access to the carb or whatever I was adjusting.

Anyway, one word of warning, the rear tank will not feed during acceleration.
The engine will lean out on hard acceleration. How do I know??? Sad experience.
A hard run through the gears overheated and seized a piston, skidding my old butt down the pavement.

So, keep it for emergencies only and make your way home carefully.