Criticism is often levelled at the Brit Twins for a myriad of reasons, the XS is an unashamed copy of the Brit twins, seems they also included more than a few design floors in their efforts to emulate the Brits. The sump filter is an excellent example. Well, it's not really a filter, more of a strainer relying on flywire type material to strain the crap from the oil.

The XS has needle roller big ends so lubrication depends more on volume rather than pressure. Cold the XS will develop around 10-12psi, hot and the pressure drops to around 5-6psi. Despite this the sump filter tends to tear, obviously not from pressure, so probably from the oil being swished around by the Crank and gears. The filter is a single layer flywire type material, the holes only being marginally smaller. The filter material is folded or corrugated for much of the periphery, but for some reason, Yamaha left a straight stretch around one of the corners. Without the folds the material is weakened and usually ends up tearing. just another of the XS650's design flaws.

To fix the problem, I fashioned a guard around the corner in question, covering the flat section of filter material. Oil can still get through obviously as there is a small gap between filter material and guard and of course the filter is immersed in oil. This guard has worked well, leaving the sump filter intact and depriving Yamaha of dollars.
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