There's a couple of M8 Facebook groups that I subscribe to and I've noticed I've been seeing a lot of posts about ACR's blowing out.

It was pretty rare that I would see a post about this happening on a twin cam when I had one.

Are M8's more prone to this?

 

If an ACR starts to come loose they have been known to blow out, no different from Twin Cam to M8. If your worried about it have them checked.

 

My 2019 did it. Helicoil no fix. Head replacement.

 

I remember it being a problem for the local dealer here in the first years.
That thread coating HD uses seems to be working better. Don't see as many loose ones now.
If it's stripped out it can be repaired

 

They put helicoils in mine. Bike still ran like crap. $3000 just after the attempted fix.

Now every time the pliugs are changed on my 24, Ill ask that the ACRs be checked. Maybe torqued.