Having now got the tank to sit where it does not clash with the forks on full lock I spent the better part of today trying to get the seat to sit in the right place. I wanted to shorten the seat base having previously extended it by about 50mm. I was anxious to get the seat/tank interface just right, with the seat enveloping the rear of the tank rather than a shaped tank rear and a straight line for the start of the seat base, also to get the base line of the seat to be a continuation of the line of the bottom of the tank. This was not easy as the tank profile changes with height above the frame rails and the leading edge of the seat base slopes downwards rather than being parallel with the frame rails.
I thought I wanted to cut off about 50mm from the front of the seat base. Rather than doing it in one hit I decided to do 25mm first and see if I could get the leading edge profile to match the tank. There was no way of measuring it. I had to hold it at the correct height with one hand and sketch the profile in pencil on the seat base that I saw 25mm away from the tank edge. It had to be done by eye alone. After the first cut and some very slight adjustment I was well pleased with the way it turned out.
I was about to copy the line made by my cutting 25 mm further back when I thought is the seat base big enough for my “bottle and …..”. Luckily I realised that it was but only just – time to stop cutting.
The next challenge was to get the seat height correct along its length. This is not helped by the fact that the seat base itself is assymetrical, one side sits about 6mm higher than the other, whilst the hump is flat and rests nicely on a flat surface along with the right hand side of the base, the left hand side has 5 to 6 mm of daylight showing. I blame poor workmanship.
I started in the middle of the seat (just in front of where the hump rises) working towards an objective of getting the bottom line parallel with the frame rail with about half the frame rail showing from the side elevation. This location gives me the best chance of setting the correct height across the whole length of the seat. After a couple of iterations with oasis foam I think I managed to get it about right so then I bonded in my saddle clip mount.
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Next I mixed up 180ml of ethanol resistant resin (Caswell tank sealer) and applied it to the internal surfaces of both the top and bottom halves. The resin is very viscous and the hardener is slightly thinner but the resultant mix is about the consistency of Araldite (on a cold day). It is difficult to believe that this stuff will flow onto the crevices when I bond the two halves together. I think I will leave this at least 3 days to cure properly before attempting the bonding of the two halves together. Truth is, I am a bit scared of bonding together job, if it goes horribly wrong as I am certain it will, then there will be a mountain of extra/repair work.