Help Need a fuel tank!! YZ426

my fuel tank is leaking from the back near the rubber strap to hold it to the frame...does anyone know which fuel tank would fit besides a stock one and if so do you have one to sell?? I put some plastic bondo stuff on it that hardened up like steel but I dont realy want to ride it again without replacing the tank...FIRE HAZARD...

any ideas?

Mine did the same thing. Just bought a YZ426 tank on e-bay last week. 50 bucks and it was in perfect shape.

Seems to be a common problem - mine did this before I had it (can tell where prior owner welded it) and it recently started again with me - I just pulled my tank and with a dentist mirror and flashlight on the outside am able to see a small 1/4" long crack in that same spot you described. The reason mine started again is that the previous owner welded to the edge of the crack, and literally left a pinhole that didn't get done - it doesn't leak unless the sun gets on it and increases the pressure in it - due to changing the breather to a spinning type - mine now closes if the airflow out is a little more than minimal and this started it all.

The tank is made from polyethylene so you can do one of two really cheap things:

1. Weld it with material shaved off the tank bottom where it's not visible (my plan).


2. Weld it with a chunk of plastic from another polyethylene container.

I have been told by a chemical engineer that polypropylene will also work but he would stick to the same material because it would have the same molecular structure. Both are safe to use for gas containers.

The hard thing is being able to tell the difference between the two materials.

Polyethylene is a little more plyable but that doesn't tell you much....

You could use a chunk off a fender or recycle bin to weld into the tank - once again though - how do you tell the difference.

Glueing or epoxy is very temporary and will likely leak very soon - those epoxies are NOT designed to work with chemicals such as gasoline.

I will be shaving off some material on the bottom of mine to use as filler and use a flat head soldering iron to do the welding, to do it successfully, you have to melt the tank and the filler together and build it up a little bit - just like regular metal welding - don't burn it - just melt it together.

With a YZ tank - don't you have to change out the seat too?

Also - reason I'm fixing mine and not replacing is because I just put new graphics on last fall and it would be a shame to lose the perfectly good tank portions.

I've got a 99 YZ400 tank in the garage if you need it, $40 shipped??

What materials do I need to "plastic weld"? I have heard of this before...but never looked into it.

Clean Soldering iron - preferrablt buy a new tip - that's flat on the end.

Some of the same plastic.

I fixed mine this weekend and tested it (pressurized it with gas in it) - shaved off some plastic strips from the corners on the underside with a sharp blade - strips were quite thin - don't need to be thick.

Carefully melt the top 1mm layer starting beyond one end of your crack and working down the length of the crack - as you go, feed the shaved off strips into the soldering iron where the crack is and smooth it out using the soldering iron - you need to melt both the tank and the filler strips together - overlaying it onto an unmelted tank won't do it.

Here's a video of a pro doing it - haha:

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