HO 50K 2
The slow process to completion continues as Captain' Mark Haycock makes his nal ascent on his K2!
Mark Haycock starts to line the tank.
When looking over a prospective project bike, you will probably take a uick look inside the fuel tank and perhaps be slightly horrified by the unappealing sight. After years of storage the inside surface will be rusty and dirty, with possibly the remains of old fuel or at least deposits from it. This need not put you off as it can be sorted out, by applying a new lining. ou might have heard a lot of stories about the fuel currently available from pumps damaging tanks and among the nonsense there is a small amount of truth. t is probably best to line tanks now as modern fuels do contain a proportion of ethylene which can give rise to more rusting than in former times. know people get rather hot under the collar about this, but if you just spend a little time preparing for it then in my experience± modern British fuels work perfectly well with old engines, though that may not be the case with what' s available in other countries. So even if the tank appears to be in good shape, a lining makes sense. There are one or two provisos here: 1) The process has to be carried out in a thorough manner. 2) The lining material must be suitable for new-style fuels, both now and in the future. t is uite likely that the paint on a project bike is not perfect and you will want to respray it, so it makes sense to do the lining before the painting. What am going to look at then is how to prepare the tank, choose the lining material and apply it. When looking at adverts for tank liners you will often nd that the sellers also offer a preparation kit and for many that will offer the simplest solution. But this magazine is for enthusiasts who like to do it themselves, so shall show you how do it from scratch. am not saying that this is the way to do it but just what works for me. f you are lucky, you will look inside the tank and nd it to be empty, clean and shiny. Returning to the real world, it will be anything but. f it has the remains of some sort of motor fuel inside, in a way that is a good sign as it shows the tank is not completely full of holes. ou need to drain it out and savour that delightful smell it produces after years of storage. believe it is caused by a reaction catalysed by the steel tank, but the fuel is now completely useless and just a liability: what do you do with it? Please do not tip it away at the end of the garden or even down the drain, but instead contact your local authority for advice. Now you can test whether or not it holds water literally, as this will show you whether or not you need to carry out repairs
to make it fuel-tight. A very slight leak is okay as the liner will seal it, but anything more will need welding. f the test is passed, you can go ahead to clean it out. f the fuel tap is actually working correctly you can keep it on for this but otherwise you will need to take it off and nd a way to temporarily block up the hole. In Photo 1 we see the tap for my CB750 K2 which, apart from a general overhaul, needs to come off for repairs as the second little brass tube has become detached. After taking it off, cleaned up the mounting (Photo 2) and cut a small steel strip to cover the hole, AET ting it and covering the whole lot, including the mounting screws both externally and on the threads, in silicone (Photo 3) . es, it looks a mess but it is temporary and it needs to seal. us e the superior oxime-based silicone (Photo 4) which gives me a bit more conaedence t hat it will work. This type is distinguishable from the ordinary stuff as it does not smell like vinegar when curing. We are going to ll the tank with a home-made cleaning uid but it is best to use something other than the normal ller cap to seal it as they often do not provide a hermetic seal. A large rubber bung (or stopper, as they are known) seems to work okay (Photo 5). They are sized by a slightly arcane numbering system: have used my number 11 (tapering from 56 to 48mm diameter) on several ller necks with success, but maybe yours is particularly big or small: who knows? Now the tank is ready to be cleaned out and for this use a hot, strong solution of industrial detergent with maybe a little caustic soda added. have found that if it is spilled on the outside, this will not damage paint provided that it is washed off immediately. ou need something to scrape away at the inside and have tried a number of things over the years. ou can use gravel, preferably with sharp edges, but that has the disadvantage that it is uite hard to get out again. This is because you will generally nd a lip around the bottom of the ller which seems to be scientiae cally designed to make it harder, but by shaking the tank it does come out eventually. progressed to using a handful of random nuts, bolts and washers which worked okay and had the advantage that it was easier to remove them using a magnet on a stick' pickup device (Photo 6). Best of all though is a steel chain which works well and is easy to remove (Photo ). With the cleaning uid and scraping arrangement in the tank, just keep on moving it around every way you can until you are thoroughly fed up with it. f you ll the tank right up you will discover that 15 litres of water make it surprisingly heavy and you will remember not to ll it up so much next time. After tipping out the contents (you have only used household cleaners so it will be okay to pour down the drain), use plenty of water to rinse it out several times and you will probably see uite a bit of rust being ushed out. Next time we shall look at a more difae cult case and move on to applying the new coating.
Mark’s back on the chain gang. It does the trick...
3 Messy, but needs to seal!
Magnet on stick works!
2 Tap mounting was cleaned.
5 Bung the bung in the tank hole!
1 Repairs needed on fuel tap.
4 Our Mark swears by this stuff.