Motorcycle Repair: 1997 Yamaha WR250 dirt bike, piston rod, reed valves

Question
Hi.  We changed the cylinder base gasket on this bike & now when we try to kick start it, 1/2 way through the kick stroke it becomes extremely hard to kick.  The bike ran perfectly before this except for spitting coolant where the old base gasket was bad.  We pulled the risk pin & kept the piston in the cylinder to do this so as to not disturb the rings.  We did have some trouble getting the cylinder to sit all the way back down when putting it back together.  The piston rod was in the upstroke and we were finally able to slide the piston back up into the cylinder head to fit it back together.  

Answer
Lisa,
 Barring any damage that may have been done while refitting the cylinder back on the studs and over the piston just two things come to mind.  Make sure there is NO coolant or liquid fuel caught in the combustion chamber.  If there is and the piston is able to push most of it up past the ports it will not compress and cause lock up.  This is unlikely but possible.  The other is that there may be a "decompression valve" on that head that was not reinstalled properly.  This valve allows eaisier kick starting on high compression engines by letting a little of the compressed air escape upon kick over.  These valves are not common on 2 strokes though.
 Also be sure there is no obstruction in the exhaust nor at the intake (before or after the carbs).  Make sure reed valves are installed correctly and that they are not stuck shut.

P.S.  Common mispronunciation, it's "Wrist" pin.

Hope this helps, write back if still stuck,
Mike