
Originally Posted by
merv
The older style 4 strokes go and go and don't wear out very quickly.
The stories around about 4 strokes relate to the newer breed of hard-out race engines found in MX and enduro bikes where they say fit a new piston and rings every bugger-all hours of riding. That's because they have very small piston skirts, super short strokes which means quite sharp conrod angles and therefore side forces of the piston against the bore, but they are built to rev like hell (13,500rpm at least) and make great power.
A KLX is not one of these (e.g YZ/WR, CRF/CRFX, RMZ, KXF) and probably would rev to 9,000. You haven't told us exactly what year and what condition coz that depends on what he can get but I'd expect them to give a good 10 years use without an engine rebuild.
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