Norton Service Release Database N45

SERVICE RELEASE N45

NATURE OF RELEASE: Inlet valve guide replacement MODELS AFFECTED: Commandoo- all years and models PARTS AFFECTED: Inlet valve guide (old part No. NMT 2011) DISTRIBUTION: Worldwide (Trade Only) EXPLANATION: New valve guides 062725 fitted with plastic guide-to-stem seals 062726 have been introduced for the inlet valves only of Commando models. The existing valve guides NMT 201 continue for exhaust applications. The new valve guides are similar to the existing guides except for the provision of a groove above the valve guide collar. The groove is to locate the new oil seal. The latest inlet guides for inlet applications only. The seals are introduced to prevent oil passing between the guides and valve stems and being burnt, causing excessive oil consumption. Under no circumstances must the seals be fitted to the exhaust valve guides.   ACTION: On any motorcycle with an oil consumption problem which shows clear evidence of over oiling via the inlet valve guides (ie. with obvious wetness on the area of the valve head adjacent to the valve guide) replace the inlet valve guides with part number 062725 (2 off) and add seals 062726 (2 off) to the new guides. This necessitates removing the i inlet valves, springs etc. , Heat the cylinder head to 90°F whilst driving out the old guides with a suitable shouldered drift and fit the new guides in a similar manner. If the valve stems are scored the valves must also be replaced, as this will render the seal ineffective. After fitting, the valve seats must be recut with a 45 cutter and the valves will need to be re-ground to the seats. May 1971 Norton Villier Canada Limited