Fuel tank tidy up. I seem to be getting on top of the 20/80 rule when it comes to making old plastic fuel tanks look ok again.
As usual, I missed a bunch of photos, but this should be enough to get the idea.
First step is to scrape off the chalky outer layer.
Then wet sand with 240 grit.
They always look great when they’re wet (above), but once the surface dries out, you can see how much more work is needed...
And repeat the sanding with 600 grit...
Then 800...
And then 1200. The 1200 is the worst - while it is wet, it looks perfect and you start thinking that it is almost finished - then it dries out and you realise that there’s heaps more to do...
Even wiping it with a dry rag doesn’t help - you have to wait until the water evaporates out of the tiny scratches.
But eventually the colour is nice and even, albeit it entirely matt.
Then a bunch of fun with the heat gun to bring the gloss back to the surface.
I borrowed a decent heat gun for this task which was far more enjoyable than using my ancient, non-adjustable one. Set to 400*C, fan on the middle setting, and the task was relatively pleasant.
There are people who can do a FAR better job than this, but for a bike that is going to be ridden, this is plenty good enough for me - 20% of the effort for 80% of the outcome!
In the past, I have put in the effort to get tanks really good, but they end up looking like this after the first ride anyway.
Today’s other fuel tank challenge was to add the dent to the underside so it clears the 200 cylinder head. I did this halfway through making the outside look good, so the photos aren’t in sequence.
First I tried half filling the tank with boiling water and using the heat gun on the outside, but the water was too much of a heatsink.
Drained the water, turned the heat gun down to 320* and very carefully heated the entire area around where I needed extra clearance. Slllooooooow process, particularly because the plastic is so thick at this point - feels like 5 or 6mm.
When I first tried to reshape the tank, the outside surface was soft/semi molten, but the inside surface was still firm - all that was happening was that I was pushing the soft surface layer off the harder, cooler material underneath. So back to heating it until the entire thickness was soft.
I really needed a roughly spherical shape, but an old glass coke bottle was the best that I could manage.
Had to keep pushing the plastic down as it cooled because it wanted to return to its original shape. My shoulders are sore now!
Anyway, its not pretty but mission accomplished!
If it needs more clearance or the plastic wants to come back to its original shape over time, then I will make up a nice mandril out of bog or something.
