I'm thinking of getting the DK Customs external breather system for my '17 Road King. Watching their videos about getting rid of the oil vapor before it enters the combustion chambers seems to make sense. But is it a good idea? I'm open to ideas especially from anyone that has actually done it. TIA

 

The ingestion of crankcase blow-by is strictly for EPA standards.

It in no way benefits the engine. Quite the opposite in most cases.

Prior to the EPA mandating the capture of crankcase blow-by, many engines vented to the atmosphere...

Whether or not it's bad for the engine, would depend on the system used to capture and ingest the crankcase blow-by..

I don't remember off the top of my head the EVO system, but I believe it was similar to the Twin Cams. I admit, I can't remember how the shovel heads vented the crankcase, but would bet they vented to the atmosphere..

On my Twin Cams, the CCV system very often would cause excessive build up of deposits on the pistons.

FWIW... I have vented all my Twin Cams other than the atmosphere...

I do not own a bike with an M8 engine.

The current M8 crankcase vent, that goes through the transmission cover, unlike the earlier HD engine venting systems, appears to work really well.

Many have switched their earlier M8 engines to that newer transmission cover system, left the vent plumbed to their air cleaners, and found that all signs of blow-by in the air cleaner completely vanished...

So IMHO, if you have a newer M8, with the CCV going through the transmission cover (I believe they are the 2023 and newer M8s), I would leave it as is.... An M8 without the transmission cover CCV system, or a Twin Cam, I would definitely vent away form the intake.

I hope this info helps with your decision...

 

I have done this with every Harley I own and owned

 

If I'm reading this correctly, the 2017 M8 does not have the later/better transmission cover system. Would this vented transmission cover do the same thing?

 

Forgot to mention this particular piece is from NICECNC.

 

What is the cost? I think the newer harley covers are less than $100, they also have 4 screws instead of six which is no issue as I installed one on my 2019 Tri Glide.

Ref:8
29400448
VALVE,ENGN BRTHR,COVER ASSY | top, with 34800071 and 34800043 (black)
Price: $88.03

 

No need for any aftermarket breather kits any longer.

Just buy the latest transmission cover for the m8, part number 29400448, and run the hose overboard, no filter or catch can.

The cover is $88.

Replace the oem breather bolts with solid bolts.

 

FYI- New HD Tranny covers are all backordered till mid March. If anyone knows where I can get the OEM cover for this, I'd love to know! Fuel Moto won't ship theirs to CA.......

 

The total from them is $74 shipped. If it does the same thing as the factory piece, I'm thinking I'll just go for it. Thanks for all the advice and learning. Much appreciated!

 

I ordered the new cover for '22 this last summer. It said it was on terminal backorder at the time, but it showed up in a week. If you want one, order it, it may show up quicker than you think.