Some rookie, Poo rider's thoughts on deto:
Not a cat 1000, but my Poo 800 just went down, PTO rod bearing, deto with twin pipes. And yes, as was stated, pipes effectively increase the dynamic compression ratio so more octane is required. I have learned the hard way. Running lean edges you closer to deto, especially if you go a little too far, so yes running a little more rich than you can get away with has a tendancy to keep deto at bay. But more importantly; good fuel, good fuel, good fuel. Trying to beat that into my brain.
You have to think about what is happening when detonation occurs. The piston is on its way up, crank spinning away with alot of rotational inertia. Then your ****ty A/F mixture enters the combustion chamber, with too low of octane, so it is very volatile and ready to explode at much lower pressures than a more refined high octane fuel. The piston continues up, cylinder pressure hits auto ignition levels for that low octane fuel and the A/F mix explodes. That flame front hits the piston top, gases expand, and try to seperate the piston from the cylinder head. If the crank is trying to push the rod up, but the piston down, you either break plugs electrodes, pistons, or crush rod bearings (sometimes a little of each). I may be off a little on the nature of detonation: maybe the low octane fuel just ignites when the spark plug fires like normal, but the lower octane fuel just burns that much faster, so cylinder pressures peak before the piston makes it past TDC. Think about it, the rod pin is trying to go up. The piston is trying to go down. The weak link is usually the rod bearings.
I do like the point WyoBoy brought up. When we mod motors, we increase power output, but then go to altitude and then even with mods we're well below stock output at sea level. So for us high altitude riders, the argument that mods put too much force on a stock bottom end and is what takes them out is garbage, unless the bottom end in question was never robust enough to withstand stock (at sea level) power output.
Not a bad year for a sled to break though. ha