watch out when heating and molding a tank

[dannygraves]

this could happen to you!


I only needed to push it in anothe 1/4" at the most to clear the head stay and look at what happened... it went pop and that was the end. anyone have any ideas on repair???
atleast I kept my stock tank!

[AlisoBob]

I know how Brit would do it....




+

[lewisclan]

suck fest

[Ported&Polished]

That does blow. Maybe a post on how to do it sucessfully is in order. I personally have zero experience with that kind of modification. But there must be a few hoons that could suggest the way they did it.

[ShanMan]

That stinks dude.....hate to say it, but that tank is toast. That hole is far too large to repair. Now then, my best results have been as follows:

Rinse the inside of the tank with water/simple green solution. Once cleaned, start the heating process. But wait, let's back up a second and talk about knowing how much you need to move the walls of the tank.

If it's a stock tank, the answer is not much at all if your headstay design is clean. In fact, at the location of the spark plug, you probably don't need to do any mods at all. The far better solution is to use the shorty plug. Even then, your likely going to have to pull the tank to swap a plug. The engine is an inch taller than the 250, and that is the price you'll pay for those extra 20 ponies. If you are trying to run a desert tank on a gen. one, things get much tighter in a hurry.....blech!!!

Now then, to clear the headstay junction: get some modeling clay and pack it all around the fully assembled headstay to head to frame joint. Be sure there is at least a half inch of clay that protrudes all around the top and both left and right sides. Now carefully put the tank in position and press down so you create a negative impression into the clay. This will tell you where you need to push in the tank for a clean fit.

OK, back to the tank heating and reshaping exersize: The heating must be done with a good heat gun. Nothing else will do the job. You should have marked the areas that need to be pushed in and ideally, written how far as well (i.e. a cloud shaped area with the number .25 written in it). Now begin heating the area with the heat gun. Here is the trick: heat at least TWICE OR MORE as much of the surface that will need to be moved. You will need to make the tank very hot, but not hot enough to start the tank turning brown...obviously that means it is burning. Once the area is hot and pliable (it might turn a little shiny), you need to work somewhat quickly to get the job done.

HERE IS THE REAL TRICK: Use something large that is not metallic to do the pushing. I had my best results using a wooden bat. The reason for a non-metallic object is that you do not want to conduct heat out of the tank. This buys you a little more time, which is critical, because you DO NOT want to have to reheat the tank. The plastic will become slightly more brittle with heat cycles, and as you move the plastic, the wall thickness will become less uniform. This is why you use an object that is larger than the area you need to move and you heat a much larger area as well, to spread out the stretching to keep the tank as stress-free as possible. If you push in the tank with the round end of the barrel of the bat, you keep the stress point to a minimum. If you need to move an area that is smaller, try using the end of a hammer handle...that works too.

Anyway, this method worked well for me, and I know if you are careful and pay close attention to the details, it will for you as well.

One last thing: If you can have a buddy working the area almost constantly with a heat gun to keep it hot (but not get it hotter and risk a blow-through) while ytou are doing the pushing, it might help. If nothing else, you'll have someone to blame when you put a big hole in your tank!

[Ported&Polished]

See, there it is, the voice of experience. Good post Mr..

[ShanMan]

Happy to help!

[dannygraves]

you da man!!!
too bad I couldn't read this BEFORE I messed up...
Oh well, I'll just have to get another desert tank, although maybe this time I will get the 3.0 gal instead of the 3.7, I imagine that would make it easier.