So middle of last year, I was at the track, flying down the straight when all of a sudden I lost power. The engine sounded really funny, and had a really weird vibration. I limped back to the pits to check it out. Started it again to have a listen. The engine was rattling and wobbling, my day was done. I've only done the basics on a bike, oil/coolant, bleed brakes that sort of stuff, so I had no idea what was wrong with the engine. I actually thought it had dropped a valve or something. I booked it into a bike mechanic for them to have a listen. They poked around at a few things, checked the timing etc. But told me it was something in the bottom end of the engine, and would likely need a rebuild. I asked how much.... around $2 – 3000 was the response. Considering I only paid $2k for the bike, It wasn’t worth it. So the bike just sat there for a few months while I decided what to do. I have a complete service manual, and my dad owns a workshop which was going to be vacant for nearly a month over xmas. I was on holidays, So I thought, I'll just rebuild it myself! I've got nothing to lose.) So with not much mechanical experience with bikes, with a friend to help with the heavy lifting. I got started. It was surprisingly easy to get the engine out of the bike, taking photos of everything as I went, marking all the plugs with coloured tape, and using labelled zip lock bags, I had the engine out of the bike in one afternoon. Then following the service manual step by step, managed to separate the crankcases. And I found the problem. It had “spun a bearing” a new term I have just learned. Not only did it spin the bearing, it had worn the crankshaft beyond its service limit.