I've owned & extensively used numerous Shoei helmets, including a few Shoei GT Air 2's, and I frequently remove & wash the liner & pads with no ill effects, but lotsa benefits!!
Things can get fairly hot here in Oz, and even with a snoopy hat or helmet liner, when you're wearing a helmet while working things pretty hard in/on a hot machine, those liners & pads get pretty stinky pdq; and if you
DON'T wash them fairly regularly, then no-one will want to come within miles of you!!
I've even been known to buy a second liner & set of pads with a new helmet, so that I can then swap a new set in as I remove the dirty set to wash & dry them - that way, the helmet is always ready to go and if I don't happen to have another helmet on hand, I don't hafta wear a helmet with still damp liner & pads fitted. Let me just warn you in advance that from my experience, even if you have absofreakin'lutely
NO choice, wearing a helmet with a still damp liner & pads is simply not nice at all, even if it is
juuust a little less disgusting than wearing a helmet with sweaty and manky liner & pads!
So go ahead, remove the liner & pads and wash them iaw the directions - you won't hurt anything... Well, not unless you've left them all in there for so long without washing them that they are now completely manky and falling apart when you do eventually get a round tuit!!
WASH THEM!! You know you want to! 