500cc twin crankshafts with full-circle end cheeks

[fdgconcepts]

Some years ago I acquired a 1955 AJS Model 20 twin in very poor condition. Upon dismantling the engine I found that the totally clapped out (0.060" undersize and ovalized big-end journals) crankshaft featured full-circle end cheeks instead of the bob-weighted style shown in the 1955 parts book.
Nowhere in any of my numerous reference books can I find any mention of cranks with full circle end cheeks. Nonetheless, thanks to a Club member I have been able to source a serviceable replacement crank (standard grind even !!!), but this one also has full circle end cheeks. Can anyone enlighten me on the manufacturing years for these cranks and could one be safely used in a 1955 twin without special precautions?

Related question: In Roy Bacon's book, "AJS and Matchless, the Post War Models" on pages 80/81 the exploded line drawing shows oil thrower discs fitted on both ends of the crankshaft between the roller bearings and the (bob-weighted !!) crankshaft. In a box of miscellaneous bits I inherited with my bike there is at least one of these discs. Could it be installed on the drive side of my (full-circle) crank without without problems (sufficient axial clearance ?), or is its use totally superfluous?

This is probably not the place to post technical queries of this nature, but I find no-where else on the website to post them.

The website could definitely benefit from an e-mail enquiry facility.

Please reply to Denis Grafham (member #4188) at: fdgconcepts@wanadoo.fr

[Eric]

Denis the Help part of the Forum is exactly the place for your technical query. Its here where those who may know about things mechanical on a 1955 model 20 500cc twin will pop in from time to time to see if they can help. If there was only an email it could only go to one person who may know nothing of your specific problem, but this way you have the potential of the entire internet active membership.