Is it possible to get a plastic tank welded...

I don't know... pity you are in OZ, who knows how much shipping will be.

http://www.ebay.com/itm/2007-KTM-Superd ... 5961wt_898

Not mine by the way.

Seller quotes $96US shipping to Australia, not a bad price considering how much shipping stuff from the US to us here in OZ can cost!

Some plastic, polypropline for one, can be welded using welding rod of the same material. Look for extra plastic on your tank you can cut off and melt over your repair. You can use a soldering gun to melt the plastic together. I hope the area you need to repair is small. I really hope you can source another usable tank instead of making a repair. One less thing to think about while on the track.

I guess it goes without saying that welding fuel tanks can be dangerous but I'll say it anyway just in case you've never heard
of anyone getting killed welding an empty fuel tank. I know you are not talking about naked flame BUT it would be a shame ...
Good luck.

Depends on the kind of plastic used. If it's a thermo-softener (getting soft and sticky when heated) it should be possible when using the same material as the tank is.
If it's a very thin crack you might be able to fix it with just an soldering device.
You might want to use something like explosafe on the inside to get an extra layer of fuel-proof lining.

To be safe flow compressed air thru the tank when adding heat.
Here is a true story from my youth. I had a gas leak on my Ford car gas tank. Small pin leak. My cousin lived next door and he said he could braze the hole. Fine. I remove the tank. I know it's the fumes in the tank that will light the sky. We lived in the sticks and had a well and cistern for water, and not much of it. I started to fill the tank with water to void the fumes. My cranky dad came outside wanting to know why the pump is running non-stop and to make it stop....his house / rules. Fumes....so the next best thing is snow but it was slow going getting snow into the small opening....then here come cousin draging his tanks thru the snow in a hurry.....looks good e-nuf for him..not me. He lights the torch and gets busy, me standing behind him for protection watching with glasses. It shot water and snow out the inlet for about 20 feet. My tank looked like a huge hot dog. Changed shorts and went to a wrecking yard and bought a used tank for $15 USD.

The tank is polyamide ("Nylon") - see other threads on this. To heat weld it, it generally requires much higher heat than most plastics (and greater temperature settings than most conventional plastic welders can achieve) to accomplish properly. It can also be vibration welded, which offers greater strength, but that's a bit more exotic.

I'm sure there are vendors in Oz who can do the work - finding them may be a challenge. Just be sure to tell them that its A) a fuel tank and B) that its a polyamide.

I was told that nylon will not be a problem so I'm sure you could find a guy near you and save the hassle...
Although I do hear that JB weld is like duct tape... It fixes anything

Well... I definitely won't try it then, I've never used it, just heard of its virtues extolled on the interweb.
I'm a diver and for fixing things we have the holy trinity.
Cable ties.
Duct tape (cloth).
Sikaflex.

If we can't fix a one off multimillion dollar installation with these, then it's unfixable

Perhaps you could use a soldering iron to melt cable ties into the crack, then Sikaflex some duct tape over the top to really seal it in?

appreciate the input guys...a quick search results in options of either getting a plastic welder and nylon rod (which would be ridiculously expensive for just one repair) or a glue called plastic surgery. http://www.itwconsumer.com/devcon-produ ... %20Glue-41

will try to acquire the glue and do a test patch first...desperate times-desperate measures