After the OEM chain on my 2003 Crf230f literally snapped in half, bending the exhaust valve in the process (but that’s thankfully all the damage it did), ProX’s Crf230f timing chain came to the rescue and it works absolutely perfectly!!! My rebuilt 230f also has ProX’s intake and exhaust valves which are better than OE quality and I’m looking forward to years of problem free riding. Thanks, ProX!!