998 Valve spring set?

[Turboflash]

Thread question is do 998 (SW & Cat) valve springs fatigue, or take a "set" when they sit compressed for a long period of time such as between riding seasons? For that matter, is this a factor at all on ANY 4S motor? My thinking is IF anyone has definitive evidence or proof that that they DO fatigue, then the motor should be turned over periodically and maybe preferably started every so often. What do our experts on TY say?

 

[HURRICANE]

We have not seen evidence of the stock valve springs fatiguing from sitting. Possibly the higher tensioned aftermarket springs but nothing that we’ve been able to put a finger on

 

[Mototown]

You might have a problem with aftermarket springs , but experience with original Yamaha parts on motocross heads , Yamaha is by far the most reliable valve train , & road bike motors are just the same .