Triumph Norton BSA 500 650 750 850 Auto Advance Spring SET 54417992 HEAVY DUTY BSA Memorabilia ) One side shows specifications

) One side shows specifications for the '70s 750 GT

These parts should fit most 500 and 650 Triumph Pre-Unit machines with 4-spring clutch

The key is dead simple

as fitted to the last round-cylinder master cylinders of the early-to-mid eighties

Triumph 3TA 5TA T100C T100R 1964-1974

Triumph Norton BSA 500 650 750 850 Auto Advance Spring SET 54417992 HEAVY DUTY BSA Memorabilia ) One side shows specificationsThis pair of springs are to suit just about all "automatic advance" ignition units fitted to unit British singles, twins and triples of the '60s and '70s. Heavier tension to cope with modern, lesser octane fuels, less issues with pinging. Original Lucas part number is 54417992. These springs are tested for tension, and are as original Lucas back in the day.