Breaker weight spring set. Heavy Duty - 70-99 B.T.(excl. TC); 71-03 XL (NU). With mechanical advanced ignition 3545 Note: See 508375 for replacement

Note: See 508375 for replacement foam filter element

Kit includes 2 intake and 2 exhaust seals

No matter what you choose

long-lasting construction

Small 1/2-oz (14

Breaker weight spring set. Heavy Duty - 70-99 B.T.(excl. TC); 71-03 XL (NU). With mechanical advanced ignition 3545 Note: See 508375 for replacementStronger 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.