JA Purity IV JA Purity IV
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  5. F131-3R Instruction Book 1937
  6. Piston Rings

Removal

To remove the piston rings, insert three or four thin metal strips between the rings and the piston. Slide the rings over the piston, taking care not to bend the rings any more than is necessary to remove them and not to distort them, as they are rather susceptible to breakage. Special care should be taken with the scraper ring as owing to its construction, it is very easily broken.

Fitting New Rings

If new rings are fitted to the piston during decarbonising, it is most important to check the ring gaps before finally assembling the engine. Place each ring squarely in the bottom of the cylinder bore about 1" up. Now with a feeler gauge verify the gap between the ends of the rings. The gap for the top rings should be .010" minimum. The gap for the scraper ring should be .012" minimum. Under no circumstances must the clearance be less than these. Rings supplied by us are correctly gapped.

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  • Velocette Documents
    • GTP Manuals
      • F40/5R GTP Instruction Book 1951
    • KSS, KTS Manuals
      • F236/4R Mk. II OHC Instruction Book 1950
      • F42/3R OHC Models 1925-1931 Instruction Book
    • MAC Manuals
      • F469/4R MAC Service Guide 1965
      • F466/2R MAC Owner's Handbook 1955
      • F50/7R MAC Rigid Frame Service Manual 1955
      • F50/4R Supplement
    • MOV and MAC
      • F131-3R Instruction Book 1937
    • MSS Manuals
      • F477 Owners Handbook 1954
    • Venom, Viper, MSS
      • F485/1R Owner's Handbook 1956
      • F484/9R Service Guide 1967
      • F484/11R Service Guide 1971
    • Valiant Manuals
      • F62-1R Service Manual