The 70-9989 exhaust camshaft part number was designated for the 1970-1972 Triumph 650 models, but it’s E3134 profile was also applied to various earlier part numbers, among them E5047 and E10041.
The current version of the 70-9989 exhaust camshaft features a nitrided finish to minimize wear and is forged from a solid blank. 70-8801 R-radius cam followers are suggested for use with the “Q” camshaft profile to maximize the mid-range engine performance that this camshaft is known for. This camshaft is often paired with the 70-3134 inlet camshaft to provide great mid-range power from the B-range engines, including the later 750 engines From LF Harris in the UK.
The camshaft is considered the “brain” of the internal combustion engine, as it synchronizes the valvetrain events that contribute to determining the character of the motor. The camshaft works in harmony with the cam followers, pushrods, rocker arms, valve springs and valves to produce the sequence of valvetrain function in the Triumph twin cylinder engines.
The crank cases must be split to access the camshafts in the unit- construction Triumph 650 and 750 engines. Once fitted, careful attention must be paid to cam timing to ensure a properly functioning engine. Refer to the factory workshop for camshaft installation and timing specifications. Special tools are required for removal and installation of the camshafts.
We sell this cam paired with the legendary 70-3134 inlet cam click here
For Triumph 650 & 750 cam bush sets 1970 onward click here
For our complete selection of camshafts click here
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