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I Have a 2005 CRF150F and the valve broke off and blew up the engine, The cylinder still looks great but the i want hone it myself. If I get it honed do I need to get an oversized piston? or oversized rings? Im going to get a new head.

Thanks, Pat

I recommend that you gauge the cylinder to be sure it is still in spec. Your service manual will give you all the spec's.
If it is then just use some Scotchbrite pad and light oil to "scuff" the walls in a criss-cross pattern. All you want to do is remove any tarnish and just clean it up. You will be good to go after that.
Good luck on the rebuild.

So don't hone it at all? also how should I measure it if I dont have a micrometer?

also the timing chain cover looked all eaten up on the inside, any idea why?

Not seeing it I cannot tell what your cylinder condition is but they are tough,tough,tough in modern bikes.
I suspect if you look closely you will see the factory cross OEM pattern still on the walls. If you do not have the measuring equipment I would say that a local bike shop or machine shop can help you out. I hope you have a Honda service manual - it's invaluable.
If you aer satisfied that the cylinder is ok then I would do the cylinder wall cleaning up and a new set of rings,piston, wrist pin bearing ect... The chain cover looks like it took shrapnel hits. Take a good look at the lower end also.

why would shrapnel hit the timing chain cover though? there is some cross hatching on the cylinder but it is also gone in someplaces. There isn't any scoreing though.