Vintage Dirt Bike Q & A

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 Post subject: 1977 Mx-3
PostPosted: Sun Apr 01, 2012 6:38 pm 

Joined: Sun Apr 01, 2012 10:42 am
Posts: 1
I have a 1977 can am MX-3 that I started a restoration on today. I have it completely torn down, and I working on getting 30 years worth of dirt and grime off of it. I was wondering if anyone on here knew how to restore the plastic gas tank on them? I have heard people that say paint it, and I have heard that you can polish them. I sanded on it a bit today and let it sit for a while. When I came back, it had started to bubble up AGAIN. I need to fix this problem. I would like to keep the original tank.

Any help yall can give me would be greatly appreciated. This is not my first restoration, although it is my first dirtbike resto.


I have attached a pic of the bike before I tore it down today, its def a diamond in the rough. Haha

362_28902052249_586842249_840512_6747_n.jpg [ 76.82 KiB | Viewed 2039 times ]
 Post subject: Re: 1977 Mx-3
PostPosted: Thu Apr 19, 2012 7:18 pm 

Joined: Fri Sep 19, 2008 8:31 am
Posts: 21
That tank is made from polyethylene, which has 2 properties that cause problems over time. The first is: Nothing likes to stick to it - it's like plastic teflon. The second: It is porous, which means gas fumes leach through the plastic causing bubbles under the paint.

There's only a couple of ways you can restore a polyehtylene tank and have it last. The first is to "flame treat" the outside surface of the tank to cause an ionization change to the surface molecules, and then apply specialized polyethylene compatible expoxy such as, flexset epoxy, over the outside of the tank, effectively sealing it.

The second is to find a chemical that you can apply to the inside of the tank that will prep the surface to allow a compatible epoxy based liner to be applied. There are companies out there that have a chemical prep for polyethylene nowadays.

There is actually a third way, but it won't work on your tank because it has had gasoline in it. Flourination of polyethylene. will put a seal on the outside of the tank, but they would only do a new tank that has not been contaminated.

You will run accross some people that will tell you they just painted it and it's fine. If that is tue, then it's not polyethylene, and if it's not, well, they lied.

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