Norton Service Release Database N69

SERVICE RELEASE N69

NATURE OF RELEASE: Summary of oil consumption causes MODELS AFFECTED: Al 1 Commando DISTRIBUTION: Worldwide (Trade only) EXPLANATION: From previous experience it is apparent that excessive oil consumption has been caused not by any one deficiency but by the cumulative effect of a number of problems - some extremely basic but some of a minor nature. These problems fall into two categories - common problems and less likely ones, but nevertheless, problems which are known to have occurred and which should be investigated in any obstinate case. Factory Production Changes We have already introduced onto production those modifications necessary to combat excessive oil consumption figures. The factory improvements with introduction engine numbers are listed below but described in detail in the main text Common Problems   ACTION: The rectification for any Commando showing continual evidence of excessive oil consumption should be dealt with as follows, but at all stages ensure absolute cleanliness of all parts receiving attention:- 1) Taper Piston Rings On any motorcycle returning an oil consumption figure heavier than 200 miles per pint, replace the middle ring on both pistons with the special ring 06-2262. It is essential to fit these rings correctly with the word Top facing upwards so that proper oil control is gained. This special type of ring is identified by a chamfer on the inner diameter. 2) Scraper Piston Rings Spring expander tyoe oil control rings have been introduced, The piston bodies are revised to accommodate the spring expander type of ring for this reason it is not possible to use the later rings on an earlier piston or vice versa. For spares purposes the revised pistons with rings as a pair can be used to advantage on previous Commando models. It is not considered good practice toassemblean engine using one old type and one new type piston. The part numbers of the old and new components are detailed below: 3) Inlet Valve Guide Seals New valve guides 062725 fitted with plastic guide to stem seals 062726 have been introduced for the inlet valves only. The new valve guides are similar to the previous 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, with seals service previous guides for inlet applications only. Under no circumstances must the seals be fitted to the exhaust valve guides. Where there is obvious wetness in the area of the inlet valve head adjacent to the valve guide, replace the previous inlet valve guides with the latest sealed variety. This necessitates removing the iglet valve, spring, etc. Heat the cylinder head to 90 F. whilst driving out of the old guides with a suitable shouldered drift and fit October 1971 Norton Villier Canada Limited