So those of you who have been following this blog will know that the GSX motor I bought with the other bits is not so healthy – it needs a rebuild really – and if I am doing that I may as well tune it.

Following the recent Cadwell ride a couple of things are obvious:

  • 91bhp is not enough to lug the old bird at a respectable rate of knots
  • Ground clearance is an issue
  • The motor is in need of a rebuild

As we head towards the back end of summer, with my back in pieces, my mind is turning towards Winter, and where we go next.

It’s all solvable given time and money, and I have a wedge of cash tied up in a 4 wheeled project which will be up for sale eventually. I started to look at the cost of totally fettling the GSX motor – I reckon for the money I’d throw at getting the GSX motor pulling anything near respectable power (125hp is possible), I started to think it might be worth exploring an engine change.

The SpaKat website highlights the cost of tuning a GSX lump properly. Sure it would be air-cooled, but in fairness I’d be putting an oil cooler on it once we got to that sort of level anyway. I’d also need to be looking for an EFE top end (can you say rocking horse poo?), never mind finding someone who has time to to do the engine work. So I sound like I have convinced myself the rewards are not great enough. Watching OSS member Johnny throwing his GSXR1100 oil cooled monster around Cadwell has set me on a path for an oil cooled engine from a late GSXR.

Right at the start of the project I was thinking Bandit 1200 motor anyhow – with the offer of a worked on top end waiting, I could see a relatively simple 130hp. Well the offer was there, but Phil (at Cambridge Motorcyles) now needs his tuned head with the death of his turbo B12 engine.

So I’ve started looking for and 1127 motor from the last of the GSXR1100 models pre-watercooling.  It’s lighter, narrower, and will fit into the Kat 750 import frame.


Photo credit OSS

The more I look at the budget for the GSX motor, spending that money on the GSXR1100 would give me nearer to 150hp, 90ftlbs, and that would be about perfect from my point of view. Reading and digging into lots of websites and blogs, it seems that the stock valves and bottom end are more than up to the job. Most of the power comes from head work (gas flowing), and a higher compression 1216 big-bore and a good pipe. Easy-Peezy, just need to find a donor motor :o)

Watch this space.