I checked mine at about 7000km. The inlets were too tight and the exhausts too loose.

I didn't do anything to the radiator. From memory I used a 1/4" socket ratchet and extension bars + 5mm allen key fitting, and reached the mongrel bolt with a bit of swearing. Did the job and refitted everything - more swearing - but it didn't take long, really. Just unnecessarily fiddly for a biggish engine.