Crf250r rebuild troubles
  • Crf250r2008
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    Joined: Mon Nov 27, 2017 12:20 pm

    Crf250r rebuild troubles

    by Crf250r2008 » Mon Nov 27, 2017 11:03 pm

    So I recently bought a 2008 crf250 with big end bearing fail so bought the mitaka rebuild kit and fitted it no problems so far but when it came to starting the bike it would not start at all did eventually get it running from a bump but it only ran for about a minute then droped a exhaust valve and smashed the head an piston. So I've ordered a new second hand head and a new piston how can I be sure the same is not going to happen when I fit the new head an piston any help will be much appreciated
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    Re: Crf250r rebuild troubles

    by crfsonly » Sun Dec 03, 2017 6:47 pm

    We're not familiar with the mitaka brand so I can't speak to the quality of their products. Using second hand parts is almost always problematic. The problem with an engine with catastrophic engine damage there are often parts damaged that are difficult, if not impossible, to see with the naked eye. Many parts are heat treated and often engine damage is a result of oil deprivation which also means the engine experienced extreme heat during failure. This extreme heat can reduce the heat treatment of these parts and they can subsequently fail. It's also not uncommon for used valves to fail if reused under these conditions. Springs may no longer offer the correct spring tension or they can outright fail. Valve stems, cotters and retainers wear as a unit. If a valve is installed in a different used retainer with different used cotters they can fail causing a valve to drop. So, the best way to ensure there won't be continued engine failures is to replace all affected parts with new OEM or quality aftermarket parts.

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