I've been treating my fuel tank now for a week, trying to rid myself of the rust an scale that's on the inside. I think I've gotten it done, but I have to ask, why don't the manufacturers use aluminum or plastic for the fuel tanks?

You could prevent fuel system contamination this way. I just don't get it.

Feedback?

 

People do make aluminum gas tanks. But aluminum is more expensive, you have to use thicker aluminum, and it's harder to work with. That doesn't work well for manufacturers. It's mainly an aftermarket deal. But a lot of choppers and cafe racer's use aluminum tanks. Jeese James even made one once on one of those chopper build-off shows

As far as making them out of plastic, well, have you ever held a 4 gallon jerry can? It weighs a lot, and mounting that plastic to a motorcycle frame, dealing with the heat (causing plastic to get softer), the risk of sliding a bike on the pavement, etc. It wouldn't be very smart.

But I've seen some completely carbon fiber gas tanks - now THOSE ARE COOL.

 

To add to what Conrice said...

Ever hear about those Ducati gas tank issues? The plastic tank idea doesn't really work well because the fuel (ethanol treated fuel that is), heat and other factors cause the tanks to expand and contract. The Ducati tanks are pretty bad on some of their models to the point where people have had 3-4 new tanks installed on late model bikes.

 

One other issue concerning plastic is safety. In the unfortunate event of a slide or crash, plastic is much more likely to rupture allowing fuel to be released and maybe combust.

 

I can attest to that. I swapped out my plastic tank for the DP aluminum one (which actually cost the same as a new OEM plastic one..) I did this before I moved back to the USA and had to deal with the E10. In Italy, there are zero problems with fuel deforming the tanks.

 

Ethanol is some pretty nasty stuff...

 

If they were made of plastic my magnetic tank bag would keep falling off. Very dangerous and distracting.

 

I don't understand how plastic wouldn't be a good choice here - just look at dirt bikes to see that plastic tanks are really more durable than you imagine. Heat deformation is minimal as the four stroke mx bikes run really hot when you're banging a 450 single off the limiter for a half hour non stop. It's pretty few and far between to see a tank that's been punctured by a stick or a stone, and even when they do slide out the frame is covering the tank and preventing the bike from sliding on the tank itself. If you need proof that plastic tanks can take the abuse on the road, search up supermoto crashes. The tank is protected by the frame and prevents asphalt from wearing through it.

You're right - ethanol is some nasty stuff. We've been using it in our plastic MX tanks for years now with nothing more than a leaky petcock seal every few years.

Steel is the OEM choice of material because it's easy to stamp into shape, easy to weld, provides good abrasion resistance, won't shatter or crack when dented (unlike aluminum) and is really really cheap. I'm sure it was in the game plan to have people buy replacement tanks when theirs rusted through.