i have a 2007 honda crf250r dirtbike i resently did a tear down on it. i took the head off and cleaned the piston. i have it all together now but it wont run. all the timing is right, there is spark. any ideas?
If your certain your timing is correct, check your intake valves they are probably tight. Honda's intake valves are garbage. If you want longevity, go to a stainless steel valve rather than a titainium. hope this helps.
Also since you went that far you should have replaced the top end. Was just a pull away and would have last a few more years. Forged pistons don't last as long as a cast piston does.
You should check your valve clearance. When they wear they tighten up, and when they tighten they stay open, giving you not enough compression to run. If your ring end gap is larger than .018" replace them.
the gaps are good, i took the head off and put gas on the valves and everything to see if they need to be reseaded but the gas was still there the next morning. i am stumped with this one, i built up a raptor 250 and she runs like a charm.
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