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Back on Two Wheels: Sealing the Petrol Tank

If you are really lucky, you found it in your own garage or it was owned by a family member. If you are somewhat lucky, a friend or neighbour had one tucked away in their garage left over from the middle 70’s petrol crisis or a crazy whim in the 80’s. If you are a little bit lucky, you got one from one of those guys that advertises for leftovers so that they can take them apart and sell the pieces one by one.

If you aren’t lucky at all, you just keep checking the internet, losing auctions, and finally spend too much for something that ought to find its final resting place in a used parts bin. To add insult to injury, you probably have to pay to have it delivered to your driveway and for good or ill, it’s all yours. You have finally gotten back into motorcycling!

Luckily, you still have your old tools because you did all the wrenching yourself back in the good old days when you were riding that metric parallel twin around town. There it is in your driveway: the battery is sulfated, but you expected that. The motor turns over; you made sure of that before you paid. The carburetors are clogged, no doubt, because that’s what every ad says: “Was running perfectly just a year (or five) ago.

Needs tune-up and carbs cleaned.” The tyres are dry-rotted, the brake calipers stick, the tach won’t work because the cable is frozen or broken, the horn button and starter buttons may be missing and if they are there, the switches won’t work, and the seat is ripped or has hosted families of rodents for decades. The windshield is opaque (you never knew that could happen), the tank is dented, one of the side covers is missing, there is an American threaded bolt holding the gear shift, the tank mounting rubbers are missing or have turned into diamonds from pressure and age, the oil sump has at least an extra measure of something that you hope is oil and not water.

And the clear coat is missing from forty percent of the painted surface. In other words it is just about what you expected from a twenty five to thirty five year old Motorbike. Nothing you can’t handle. You’ll be riding in no time. Better look for the helmet and pay for the motorbike insurance. But before you start cleaning and draining and tightening and removing and rebuilding, take a look inside the petrol tank. Get your flashlight because you may think your eyes are playing tricks on you.

You can temporarily unstick a caliper with a sharp hammer blow, but what are going to do with the rusty poisonous mess inside the petrol tank? I’ll let you figure out what to do with the part petrol, part water, part rust fluid that you drain or drip from the tank when you remove it from the Motorbike. I thought about dumping in the back of the garden, but besides being illegal, it just isn’t good for the plants. I wound up putting it in an old plastic jug that used to hold antifreeze and finding a car parts store that would dispose of it: nothing grows in their garden either.

You have got to do something because your freshly cleaned and rebuilt carburetors will not last five minutes with that stream of rusty petrol coming from an unsealed tank. Here is what you’ll have to do:

• Go on the Internet and find a source for the petrol tank sealer. I found mine on an auction site and took delivery within a week. Don’t worry about the delay because you’ll be busy in the meantime with everything else you have to do.

• Take off all the hardware. This includes the fuel valve (for some reason it is called a petcock), petrol gauge (if you are lucky enough to have one—but wait, you wouldn’t be doing this at all if you were lucky) and any hardware that holds on the petrol cap.

• Clean out the tank with about half can of acetone that you get at the hardware store. This stuff attracts any stray molecules of water and rinses them away.

• This is the fun step: put a handful of one and one quarter inch long dry wall screws into the petrol tank. Tape up the holes and shake. Keep shaking. Shake some more. Open the holes and start shaking out the rust flakes and the screws. Keep shaking, there are still more screws in there. Did you count the screws going in and keep track of the screws coming out? No, you don’t have to do that, you’ll know when the tank is finally empty. When you are done with this step you’ll be so happy with the amount of rust that has come out, you may want to do it again. Go ahead, grab another handful of screws.

• Put the rest of the acetone in the tank and slosh and dump.

• Have you read the side of the can of sealer? I couldn’t either without taking off my glasses. The can tells you how much you need. A typical can may have enough for two doses so you can do this all again someday.

• Go to the toy store and buy some play dough. It’s more fun than your remember and your adult children with enjoy it as well. Use the play dough and some wide tape to seal all the holes except the one into which you pour petrol.

• Pour in the recommended amount of sealer and use your play dough and tape to seal off the last opening. Slowly and methodically turn and tip the tank in all directions. Visualise the sealer moving hither and thither through the tank and move the tank so that you know every part of the tank is coated. Then keep tipping and turning until you are really sure. Next time you can act as if you know what you are doing: this time be more thorough that you think is necessary.

• Take off the tape and play dough. Look at that, it’s all coated with sticky red goo. Pour the rest of the goo into the can and reseal the can and then throw it away, you aren’t really ever going to do this again are you?

• Let the tank dry for a couple of days. The instructions on the side of the can scared you with the possibility of putting in petrol before the sticky goo is dry.

• Did you disassemble and clean out the fuel valve and clean the rust off the other tank hardware? Don’t you dare put it back together before cleaning all that stuff. Put it all back together, but don’t install the tank until you are done with carburetors and adjusting the valves and cleaning and reseating all the electrical connections, because the wire to the coil is loose and its intermittent connection will puzzle you later on.

That’s it. Now there is only about another month worth of work to do. The good news is that all this bonding with the machinery means you will never ever sell this Motorbike. You will love it forever, or until it burns your ankle one too many times.

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