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Have a crf250 lately it wont start from kick was told its something to do with the valves but the compression seems very low too can you help

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Bad valves will cause low compression. When the bike was running, did it smoke constantly?, ( bad piston rings ), or did it only give a puff of smoke when started and when pulling away from a stop?, ( Bad valve guide seals ). Do a compression check. It should read around 150psi.. Chances are the valve faces are carboned up, pitted and or burned. The problem can likely be fixed by re-seating the valves ( AKA grinding the valves ). Removing the head is easy, re-seating the valves is easy, but putting it all back together and setting the valve timing and clearances is a bit tougher for the novice. Some special tools are needed. If the bike is smoking as described above, now would be a good time for a cylinder bore, new piston and rings and valve guide seals. Please rate this solution, thanks!

Posted on Jul 18, 2010

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