Classic Bike Guide - - Cbg Work­shop -


Ir­re­spec­tive of the sealer, you need to make sure the tank is cleaned and pre­pared in­side or noth­ing will stick to it. If it has an old sealer in, that needs to be dis­solved, rust needs to be con­verted and re­moved and old, stale fuel also needs to go. It goes with­out say­ing that most of the chem­i­cals and acids used here are not nice to say the least, so gloves, pro­tect­ing paint­work and ven­ti­la­tion need to be se­ri­ously tack­led. Tanks have one or two holes in for fuel taps, pumps or even fuel level gauges. These need to be bunged up with stout dow­els, as they will also need to be re­moved sev­eral times and then re-in­stated. Larger holes may need gaffer tape to fill. Lastly, you need to con­sider tem­per­a­ture, de­pend­ing on what the sealer man­u­fac­turer rec­om­mends. Ian has found his epoxy sealer works around 22°C or above for the sealer to flow well. Too cold and you will risk not get­ting full cov­er­age, so Ian also has an in­su­lated area with heat lamps to help.


Our tank hadn't been sealed be­fore, but it was rusty and it had suf­fered from pin­holes, which Nev had filled, but we wanted to make sure. Some rust re­movers claim to make the rust back into steel, but I can­not see how that works, so pre­fer the ones that re­move the rust us­ing acid. This was what Ian pro­vided and in­cluded a rust re­mover which you keep in for sev­eral hours, reg­u­larly shak­ing the tank. Iron­i­cally it's mixed with hot water, but does do a good job of clear­ing the rust, just like the rust killer you would use on body­work. •


To re­move an old sealer you'll need to soak the tank for sev­eral days with a 'pet­seal re­mover', that soaks into the old sealer and ei­ther dis­solves it, dries it out or other­wise at­tacks it so you can get it out. Some bungs will have to be made for any tap out­lets, from wood, cork or dowel. Messy and time con­sum­ing, how long it takes de­pends on the old sealer. "It's not un­com­mon for me to have to cut holes un­der­neath a tank to get ar­eas you can't reach from the filler, or even to re­move large lumps of old sealer," ex­plains Ian. Once you're happy all the sealer has gone, it's time to tackle any rust or cor­ro­sion.

The two-pack sealer comes pre­mea­sured, so you just need to find some­thing to pour it all into and stir it up. As the BMW­tank is so large, I needed to cut up a milk bot­tle, but it worked fine. As you stir it the grey hard­ener lets you see if any part hasn't mixed thor­oughly, then pour it in, mak­ing a note of how quickly it is mov­ing.

This is where I found it tricky. With tape firmly over the filler hole, I'd been used to shak­ing the pre­vi­ous con­coc­tions, but the sealer is much slower to move around in­side. And it is go­ing off all the time, so you have to plan where it's been and where it needs to go. With 750ml in the BMW tank there was plenty, but be­cause you can­not hear it splash­ing around, I found it tricky to keep a track of where I'd cov­ered. So I had to keep re­mov­ing the tape on the filler and peer­ing in with a torch to see!

Ian's tips were es­sen­tial. Make sure the top of the bridge and the front and back are cov­ered - ar­eas he of­ten sees have not been cov­ered well enough. Don't be afraid to use a fine art brush at­tached to a stout piece of wire if you need to touch up the breather tube, or any other parts not cov­er­ing. And as said, make sure the tem­per­a­ture is warm enough to keep the sealer mov­ing in­side.

Once you're happy it is all cov­ered in­side, in­clud­ing the filler, drain the re­main­ing sealer into the bin through the fuel tap holes. The tank will now need around 6-7 days to cure, with the more air flow­ing through to re­move vapours, the bet­ter. Ian uses (and sells) mini USS-pow­ered fans to help.•


Some tanks should be easy to see in­side, while oth­ers, like the BMWone, are very tricky, thanks to the large bridge in the mid­dle. I used a pow­er­ful shoot­ing torch through the tap hole and a den­tist's mirror to check around, with the only part need­ing a lit­tle more be­ing the breather tube. Luck­ily there was enough left in the milk bot­tle and I could reach with an artist's brush. If there are larger ar­eas you've missed, you can add more sealer as long as you do it be­fore the sealer has cured.


No, to be hon­est. I would pay some­one like Ian to do it. Mainly be­cause they have all the ex­tra tools that make the job eas­ier like sand blast­ing and weld­ing, they know what to do and there is so much to go wrong if you don't get it right. I'm glad I've tried it, the tank seems to be al­right, but next time I'll hap­pily pass the job on!

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