I'm guessing it's time

[Jean]

With a lot of carbon, the compression could be pretty high, for sure.
I hope you can get the pistons you'll need. Some R90 EXPERT will have to get involved with this...
So, 5 years ago, you didn't see any oil burning/carbon deposits like you see now?
While you've got the engine torn down, might ought to check the timing chain...pinging....
Hey! Good luck with this...don't disappear without a feedback report.