Engine Trouble horrible knocking sound

How hard was the engine revving when at full throttle?

butre said:

these engines often need to be a little rich for cooling purposes

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I agree.

The engine currently in my bike needs a No 77 main jet to run optimally, with fuel that is equivalent to American 93 octane and an oil/fuel ratio of 25:1

The previous engine needed a No 76 main jet.
The engine previous to that needed a No 70 main jet.
The engine previous to that needed a No 83 main jet.
The engine previous to that needed a No 86 main jet.