I think it's a CBR600, Honda always had trouble with their cam chain tensioner's.....I reckon there is a problem with the chain tensioner and its letting the chain whip that top guide.
Bob
I have seen multiple peek parts become glass like and brittle at prolonged 120 degrees C, so would not advise this.A nice block of PEEK would do a good job in there, but you'd be lucky to get the raw material for £50