Before any rebuild of a damaged motorcycle engine is done, it is imperative that the engine be completely disassembled, thoroughly cleaned, and inspected for adverse wear. Most motorcycle manufacturers say that any damage caused by a camshaft bearing failure will be contained and confined to the camshaft assembly (gearcase) and the return oil system. Motorcycle manufacturers asset that any gearcase component breakdown and the related debris does not affect other parts of the engine: 'After careful inspection, some of the motorcycle manufacturers have determined that complete engine disassembly is unnecessary. All contamination is confined to the camshaft compartment and the return oiling system.' I disagree.
I feel that fine metal particles transfer from the camshaft compartment of the engine through the pinion bearing that separates this compartment, on some motorcycles, from the bottom end compartment. I feel this occurs via suspended particulates in the oily mist that transfers back and forth between the two due to the violet pressure differentials caused by rapidly ascending and descending pistons. I also believe that debris created by a failure anywhere in the engine will usually travel unimpeded throughout the engine a few times before it is totally filtered out of the oiling system. This is because the oil filter has an internal bypass, so the filter's element does not restrict oil flow. Odds are that a metal particle can make a number of passes through the oil system before it is finally caught by the filter element. In any bypass filtration system used on all modern vehicles, including our beloved motorcycles, a portion of the oil will be filtered each pass, while another portion will be bypassed back into the engine unfiltered.
For me, if there is catastrophic damage anywhere in any motorcycle engine, the whole engine must be disassembled for at least a thorough cleaning and possible rebuild. It is also necessary to flush and clean the oil tank or pan, as the case my be. These reservoirs for sediment and particulates are often overlooked with disastrous results. Furthermore, oil lines must be flushed or replaced to remove any chance of recontamination.
Oil filtration on modern motorcycles has never been more efficient than it is now-a-day, but, you also need to understand that filtration isn't complete or total as in 100 percent. Therefore you need to demand that a motorcycle dealer disassembles your engine and rebuilds it completely after catastrophic failure.