SLOW STEADY REFINEMENT
The 1965 Triumph Bonneville T120 650 was again more or less a carry-over from 1964, which itself was a carry-over from 1963. Changes were minor and evolutionary in nature, aimed at refinement, improving reliability, performance and ease of production. Model designations were also carryovers: T120R was the road machine with down pipes; the T120C was the off-road/street scrambler (like an Enduro); and the TT Special, which wouldn't actually get its own official model designation until 1966. For now, the TT Special was an option package for the T120C series. The color scheme for 1965 was Pacific Blue over Silver.

ENGINE

Engine refinements began with Engine # DU13375 and included a drilled hole in the crankcase behind the cylinder to facilitate finding top dead center, a new oil pressure relief valve, and a change to Champion spark plugs. The exhaust system on the T120R was restyled (more swept back) and brackets added. UK and Export models retained the long mufflers, but US models got a shorter muffler with straight-through baffles. Minor changes were made to the kickstart mechanism, clutch lining material was switched to Armstrong cork, and a longer alternator cable was added to keep it from rubbing on the primary chain.

FRAME & RUNNING GEAR
Frame and running gear also received only minor attention. The rear subframe was modified slightly to make the center stand work better, the horn was hung from a new bracket under the tank, the rear brake actuator rod's operating arm was moved to the inside of the left engine mounting plate and the rod re-routed accordingly. The battery box received steel liners for its rubber mounts to prevent damage due to overtightening. The QD (Quickly Detachable) rear wheel swapped its taper roller bearings for ball race bearings.

PAINT & TRIM
Some US models got all-black seats, while most had the more familiar 2-tone gray-and-black seat, similar to 1964. The new paint colors continued to follow the same pattern as 1964, with the Pacific Blue top covering most of the tank, and the Silver showing only under the tank emblem. Of course the steel front and rear fenders were painted silver with a blue strip running down their center, except for the TT Specials, which sported lightweight polished alloy (aluminum) fenders.

Source classic-british-motorcycles.com