BobH

Hello,
 
Thanks for your reply. The number on mine is 5080, and it's an A.P.M. model like yours, so one of the later ones I think. There's one on Ebay at the moment in Northern Ireland, and that's blue like mine. However, there's also another one advertised on Ebay that doesn't look to be in very good condition. It's green and has a plate on it saying it's the AU model and the number 631. It's also got a very odd looking cutter mic, so I guess different models had slightly different cutting methods, and different colour schemes to help identify them. I must say I prefer the bright red of yours to the rather washed out blue of mine, but I wonder if they changed the colour scheme to prevent confusion between their tool and the American Van Norman boring bars which are also bright red.
 
Regarding the Rotax barrels. They are off a converted snowmobile or hovercraft engine that was used to power one of my microlight aircraft. The particular pair of barrels I've been playing with both had broken exhaust manifolds, so I decided to use them as practice bores as I don't have any aluminium welding kit to try and weld the manifold castings back on. Even if I did get them welded the face of each manifold would then have to be machined back exactly square to the original angle so that the exhaust header could bolt to it successfully. As it is I now have something to practice on with my boring and honing equipment, and I've got another spare engine sitting in the garage should I need it, so no great loss to the microlighting world.
 
I've attached some photos of the engine before the manifold castings broke away, so that you'll see where the barrels came from. The first photo shows the other side of the engine, but gives you a better overview of what the engine looks like in situ. Lastly, I've put two photos of the plane after it's had a clean. The last of those two shows the plane ready for me to go off on a flight, with a jerry can full of petrol strapped to the back seat as a backrest, and as a 20ltr supplementary tank to the 47ltr plastic tank that's fitted under the engine. This means the plane could theoretically fly with just me in it for just under 8 hours, at around 50 - 55mph, although I'd have to land after a while to top up the main tank from the jerry can. Also, my bladder wouldn't last that long, so I'd have to land anyway at regular intervals. :-)