Pick a model. Get the spec sheet — engine, gearbox, oils, electrical, chassis. Print a single page to keep on the bench while you work. Numbers extracted from the shop knowledge base — always cross-check against your workshop manual.
Technical Specification Sheet
Ref LH23-TS-TRIUMPH-T25-1971
Triumph T25 1971
1971 · 250cc · Oil-in-Frame era
Spec sheet
Triumph T25 1971
1971 · 250cc · Oil-in-Frame era
The Triumph T25 of 1971 — the T25T Trail Blazer and T25SS Blazer SS — was a 250cc unit single, the badge-engineered sibling of the BSA B25 and successor to the TR25W, built in the final year of the BSA-Triumph 250.
Engine Torque
Cold · clean threads
Fastener
ft-lbs
Nm
Cylinder barrel nuts
20
27
Conn-rod end cap nuts
27
37
Crankshaft pinion nut
40
54
Flywheel bolts
32
43
Clutch centre nut
60
81
Kickstart ratchet nut
50
68
Rotor fixing nut
60
81
Stator nut
20
27
Oil pump stud nuts
6
8
Valve cover nuts
10
14
Carburetter flange nuts
10
14
Spark plug
14
19
Gearbox Torque
Per workshop manual
Fastener
ft-lbs
Nm
Counter-shaft sprocket nut
75
102
Engine
Factory data
Engine typeOHV unit single
Bore & stroke67 × 70 mm (2.64 × 2.76 in)
Capacity247 cc (nominal 250)
Compression ratio9.5:1
CarburettorAmal 928/20 concentric, main jet 190
Tappet clearance (cold)Inlet 0.008 in · Exhaust 0.010 in
LineageBadge-engineered BSA B25; successor to the TR25W
Engine number locationLeft side, below cylinder barrel flange
Source1971 T25 Workshop Manual (99-0945) — General Data GD2/GD3/GD5
Disclaimer. Always cross-check torque values and clearances against the workshop manual specific to your engine and frame numbers. Le Hangar 23 publishes these for reference, extracted from shop knowledge — final responsibility rests with the person turning the wrench.
