REMOVE THE UPPER CHAIN ROLLER.
It is located too low on the frame, so it comes into contact with the chain when the suspension is compressed and you accelerate. Having the correct chain tension will not prevent this problem.
Nobody has ever reported any negative effects from having the upper roller removed, while plenty of people now have holes in their frame for being ignorant of this issue.
Put a small set screw or a big blob of silicone in it's place instead. Don't use a bolt with a big head that will stick out and catch the chain.
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'12 Husaberg FE570, 09 KTM XC-F/ 450 RFS hybrid, 07 KTM 450 SMR, 08+09 BMW F650GS twins/F800GS conversion, 03+05 YZF-R6