I have another update on this build thread! Yay!
After much head scratching and pondering, I have decided I won't be using the K5 GSXR1000 as a donor chassis. Apart from the fact that it's an awesome ICE bike as it is, there are some serious issues with how I will fit everything into it. The K5 GSXR1000 was shrink in almost every way compared to the K4, and even more than the later, K7s. Why I didn't notice this, I don't know. But the reality is, it ain't going to fit, and if I did try to make it fit, I would be left disappointed with the compromises.
So I have decided to get a custom frame built
It's not as expensive as you might think - roughly the same as what the donor bike cost me. Granted, I will need to attach brakes, forks and shocks to it, but in the grand scheme of thins I will be happier knowing that the bike does fit everything and satisfies true race bike geometry.
Some important considerations - the Evo AFM140 motor is big, but narrow. Therefore it needs to sit inside the swingarm such that the chain won't be reaching too far to the drive sprocket. This means getting a custom swingarm made - or does it?
Exhibit one - A Ducati supersport 800/900 swingarm:
This swingarm allows for the shock to be placed above the motor. It also has a H-shape able to accommodate the rather large Evo motor. I want to run a 160 or a 170 rear tyre such that there is plenty of chain clearance and the motor can remain centrally located (not off to one side, upsetting the balance of the bike). A 180 tyre wouldn't allow this.
On the custom frame front, I have been in discussions with Framecrafters in Illinois. Randy and Karsten have been developing custom race bikes for a long time, and have made some amazing machines. Their speciality is Chro-Moly trellis frames, although they have made some Moto3 bikes using CNC's aluminium parts. I was thinking something like this could work for Voltron II:
The trick is to ensure there is enough room for a 220 mm by 320 mm battery box which can drop in from the top, while at the same time making sure the thing isn't too fat for the rider above. It will taper at the base where the motor will have a series of attachment points.
In this earlier sketch I considered using a CNC'd aluminium motor cradle which accommodates four large supports around the diameter of the motor on 8 mm aluminium plates. By allowing the motor to be suspended in the frame from these instead of the 16 M10 holes provided, it makes it a little easier for the frame builder to mount the motor after a somewhat generic trellis frame has been made.
I think the trellis frame is a winner, but supporting the motor will be the tough part.
Now, you might be thinking how am I going to get a frame built on the other side of the world and still have everything line up when I get it? Well I can provide Randy with a CAD file of the motor and he can get it cut from cheap plate ally or something, and weld a mock motor up. Since the threaded holes will all be in the same spots, it should be straightforward to build the frame around it.
Oh, and it goes without saying, I need to sell the Gixxer to pay for this. So if you know anyone who is keen on a track bike, already set up - let me know!