2019 R1250GS TE

[Alf]

NOT left hand ticking, when engine really hot pulling in top at approx 4500 rpm. loud rattle [ear plugs in ] accompanied by what feels like engine retarding, can pull through this but returns, engine has covered approx 11000 miles. sensible clues/ideas please.

 

[Pukmeister]

If you are still under makers warranty or a used bike warranty I would be straight onto the dealers for a diagnosis and fix. If like you say it is retarding under load it will most likely need a diagnostic tester to check why.