Compression ratio and octane

I just picked up an 05 crf450 flat track bike with ported head, race cam and 13.5 to 1 CR Wiseco. The last owner was using 110 octane race gas, but I think that is serious overkill. stock CR is 12 to 1. What is the minumum octane any of you with 13.5 to 1 are running?

Use the lowest octane you can, without experiencing detonation

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