Breaker weight spring set. Heavy Duty - 70-99 B.T.(excl. TC); 71-03 XL (NU). With mechanical advanced ignition 570850 VANCE + HINES VALVE INTAKE

VANCE + HINES VALVE INTAKE BUSA 1MM TT

OEM replacement reference 12051

Allows correct adjustment of the primary chain to the factory specifications of 5/8

three sizes of lock washers and six assorted sizes of standard-thread hex nuts - all brilliantly chromed

Brake/clutch controls and switch housings with OEM style clamps sold separately

Breaker weight spring set. Heavy Duty - 70-99 B.T.(excl. TC); 71-03 XL (NU). With mechanical advanced ignition 570850 VANCE + HINES VALVE INTAKEStronger than stock. For slower advance curve, used to help solve detonation issues. Also less breaker weight rattle during idling and improves idling stability. Note that stronger springs may require carburetor adjustment (richer). Note: 516300 is standard replacement, 516301 is heavy duty, 516598 is extreme duty. Mixing different spring strengths will give additional fine tuning options.