Symptoms
Flywheels that shift out of true at the crank pin generally exhibit one of two symptoms: no oil pressure or vibration. This condition is also known as scissored flywheels.
No Oil Pressure
When the crankshaft shifts more than 0.015 in (0.381 mm), it can break the oil pump gerotors, resulting in a loss of oil pressure.
If a very low or no oil pressure condition is confirmed, inspect the oil pump and cam support plate. If the oil pump gerotors are bound or damaged, the cause is likely from a contaminant running through the pump or a shifted crankshaft. If this type of damage is found, always replace the oil lines and clean all debris from the oil pan or oil tank. See 1.26 TROUBLESHOOTING for general diagnostics of low oil pressure.
Vibration
Generally, left crankshaft runout must exceed 0.020 in. (0.508 mm) to be noticeable to the rider. It is much more likely that vibration issues will be resolved by following the checklist in 1.26 TROUBLESHOOTING.
If correct chassis set-up has been verified and other items in 1.26 TROUBLESHOOTING have been eliminated, checking left crankshaft runout is appropriate.
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