The main reason to replace the camshafts is to change the engine character depending on the purpose to use the bike.
"ST-1" is a Bolt-on type camshaft.
It is developed for sports riding or street racers therefore it is designed to improve midrange to top-end without sacrificing low end drive ability.
"ST-2", "ST-3" & "ST-R" are developed for sprint or endurance race use.
These camshafts have a high lift and extend duration. They are required to use Yoshimura valve spring, valve cotter, valve retainer, valve spring seat shim, ECU or other parts even idling level depending on the model or the condition to use. Some of the camshafts are included Yoshimura original adjustable cam sprocket & light weight cam flange.
These cams have possibility to lose low-end range as they are designed to improve the output of high top-end.
When installing camshafts, it is required to check the condition of the related stock parts. If the valve surrounding moving parts, O-ring, packing or others are worn out, you can not expect full performance of Yoshimura camshafts. Also using worn out parts causes serious engine problem.
Tuned engine is required maintenance frequently to keep the same level of the performance and for safety ride.