can I replace an '02 CR250 cylinder with an '03 cylinder?

motometal

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#1
I am helping my friend put a new cylinder on his '02 CR 250.  The old one lost the plating on the exhaust port bridge for some reason.  Also, the ends of the top ring mysteriously snapped off, gouging the cylinder.  Not sure why on either problem.  He doesn't want to wait for the cylinder to be re-plated or bored. so he is buying a new one.

My question-can he just upgrade to an '03?  Is the piston and head the same?  How about the powervalve?

also, how does the powervalve come apart?  It seems very simple, looks like the shaft just pulls out once the keeper tab is removed, but I couldn't get it apart and didn't want to pry too hard and wreck something.
 

marcusgunby

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#2
the PV often gets tuck due to carbon-i believe the 03 will fit.Sounds like your friends 02 may have been detonating and that caused the failure.
 

smarttoys

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#3
The new '02 and '03 cylinders that I have checked come with the powervalve assembly. The '03 cylinder should bolt up fine.
 

motometal

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#4
Is the piston different?

regarding the detonation, I wondered about that as well...if that's the case, would the top of the piston show any signs of it?  It is very normal looking with no pits.
 
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#7
Did it snag on the power valve, did the ring snap at the same time as the plating came of. This sounds like your mate could have a lemon barrel. Talk to Honda ?