BSA & Triumph A75, T150, T160, X75, &c.

Note

Size, CC

Bore

Stroke

4K P-speed

1

740

67mm

2.6378”

70mm

2.7559”

8,709

2

831

71mm

2.7953”

3

915

77mm

3.0315”

7,917

4

974

82mm

3.2283”

7,434

5

748

63mm

2.4803”

9,676

BSA & Triumph 750 ID:
  1.  1969-76 A75, T150, T160, X75 etc. unit construction 750
  2.  Maximum oversize on original cylinder (T120 bore size), or new big bore cylinder
  3.  Big bore cylinder and + 7mm stroker crankshaft
  4.  Big bore cylinder and + 12mm stroker crankshaft; same bore & stroke as T120
  5.  Big bore cylinder, de-stroked 7mm to 750 Random notes, in stream of conciousness order:
    Despite frequent statements to the contrary, the triple is not a “Daytona 500 with an extra cylinder”. The bore and stroke, rod length, combustion chamber size, crankshaft rod journal size, etc. are all different.     Here's the P&M / Triple Cycles 71mm big bore aluminum cylinder block: