Stopped for a fill up, restarted my 2017 CVO limited and sounded awful under acceleration. Like it had suddenly sprung an exhaust leak. Pulled over, but the sound wasn't noticeable on idle or even a few revs on the throttle. On closer examination could see some discolouration near the rocker covers on the front cylinder. It looked like burnt on oil mist. A few kms down the road to the dealer the sound disappeared but she wouldn't idle. At the workshop the dealer confirmed that the front cylinder ACR had failed. See the pictures. It appears the valve had melted right through. Interesting the ECM or BCM do not throw up any codes as the solenoid circuit is still reading OK. I understand that this part has now been redesigned by HD and carries a part nos. with a suffix B. See Pictures. I wondering if anyone else have had a failure as this. BTW. Checked the bore with a borescope cam and inside looks clean as whistle. The HD foreman tells me that it is likely that valve got stuck open and slowly melted away.... hard to believe, but there are tell tale signs of residue.

The blown ACR from the front cylinder.

The blown ACR Cap.

Missing Valve on the front ACR Solenoid

In comparison to the rear ACR

pretty mangled.

 

How did the spark plugs look in the front cylinder? To melt that ACR you were running real lean.

 

welcome and normally say congrats but 1 post in 10 years with this I'll skip that part ......$h!t happens..been a regular here since M8 inception and don't recall seeing or hearing about this type of problem..great you were able to safely get to the dealership and repaired without too much drama

 

Haven't changed anything from stock, except for installing a Jekill and Hyde Slip-on mufflers. The plugs seemed OK. according to the HD foreman, it is possible the ACR valve got stuck in an open position resulting in a excessive heating and subsequent melting.

 

Thanks. I know... I know.... not a great look but wasn't smelling roses until recently....

 

Main plugs from the Engine.


Main plugs from the 114 M8

 

Lot of oil on those plugs, but that's going to be described as "normal" for these engines, lol.