All the engine gaskets fit all CRMs for all the major parts but I don't know if there is a gasket on the front side of the cylinder head of the AR covering the power valve. This would be an AR fittment only.

Honda don't do a full gasket set anymore, so you have to buy everything seperately from Honda.

Athena do a full kit - http://www.athenaparts.com/ or http://www.athenaparts.com/eng/models/v ... -crm-250-r

These are available from Massive Racing but several members of this forum have had bad service, with no gaskets arriving and having to claim back through PayPal. I suggest you to consider other suppliers?