Oil pump drive shaft sprocket for Honda CT90 K0-K8; CT90 '78-'79 motorcycles
The oil pump drive shaft sprocket (also known as the cam chain guide sprocket) is a critical component for the proper functioning of your vintage Honda Trail 90's engine. Located behind the magnetic rotor, this 29T sprocket drives the oil pump by engaging with the cam chain, ensuring consistent oil pressure and proper cam chain operation. Over time, this part is prone to wear (a common issue we've observed) which can lead to reduced oil pressure and inefficient engine performance. Replacing a worn sprocket is essential maintenance to keep your CT90 running smoothly and reliably.
While replacing your oil pump drive shaft sprocket, it is also a good time to replace your cam chain, large cam chain roller, cam chain tensioner and engine oil seals.
The oil pump drive shaft sprocket can be removed following the removal of the magnetic rotor. With the magnetic rotor removed and tension on the cam chain released, the sprocket and shaft can be pulled out of the engine. When installing the new sprocket and shaft, ensure that the slot at the end of the shaft properly engages with the oil pump drive mechanism. The flat tab on the oil pump must fit securely into the slot at the end of the shaft. This alignment is critical to ensure that when the sprocket is driven by the cam chain, the oil pump is driven as well.
