Hi, Michael to avoid premature engine wear and damage this condition should be eliminated "ASAP" and the usual suspects are:
1. Fuel octane rating too low.
2. Compression too high due to excessive carbon deposit buildup on top of the piston, top of the cylinder bore, and cylinder head dome.
3. Engine overheating due to lack of lubrication, coolant, or lack of cool air passing by top end cooling fins due to accessories or bike not moving.
4. Engine under heavy load due to riding double overweight luggage etc.
5. Fuel-air mixture too lean or too rich.
6. Outside air temperature too hot for the load (dessert).
7. Faulty knock sensor.
8. Electronic ignition timing too far advanced due to faulty sensor inputs (MAP, CKP, CMP)
9. Points plate too far advanced or mechanical advance mechanism worn out.
10. Blocked exhaust causing excessive backpressure.
11. Incorrect spark plugs for the kind of service causing overheated tip.
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