My .02.
It eliminates, an over pressurized oil sump due to various conditions. Mine was the fact that I was, key word was, running the Stage lll 117” kit from HD that when first released (not so sure if it was ever resolved with any of the Stage kits) were poor fitting cylinder to ring clearances and all. It is not a fix to anything, call it a band aid to a problem or a way to exhaust the oil sump when going big bore that the breathers can not handle.
Also in my opinion it eliminates the need to reroute your breathers to stop even stock bike from burning that mess. Since my build of my 124”, I have continued venting the oil sump and have yet to find any oil or condensate collecting on my throttle body.

 

My thoughts are, My bike don't need one, and I doubt your bike needs one.

 

I just ordered one for my 114 M8. Spent months asking the same question, and finally said screw it. It's $99, and it certainly isn't going to hurt anything. It may not actually do anything either in which case I'll chalk it up to I spent $100 on something I did not really need. No big deal either way, however if it actually does work I;d rather ahve it than not have it.

 

I did the A-1 vent, it was reasonable and he is knowledgeable. My Stage 2 was seeping around the dip stick, never has it leaked from the AC? Mine uses oil so I assume the ring seal is not the best. I’m hoping a Fuel Moto big bore kit will help. 17 RG, RS 468, SE ventillator, 2020 oil pump, S&S lifters, adj pushrods FM slip ons, PV-2 with an outstanding FM tune.

 

I meant they used to vent to atmosphere decades ago

 

On what model engines?

 

So I took the dip and purchased the A-1 vent kit for my 2020 FLHTK (M8) with the 122 kit build. The seat of the pants feel is better and I plan on borescoping and taking an image of the new piston tops as they only have about 4 hours runtime so far. My 2016 FLHTK motor went down and the tech showed me its piston tops. Each was caked with a layer of carbon build up. The motor was a stock 103 with air/pipes/fp3 kit install and about 51k miles on motor.

 

So you are saying you feel a performance increase from a vent? Thats... interesting - is the only word I can come up with.

I guess I could have saved money and not done my 128 kit...

 

Installed the Fueling Vented Dip Stick and put the filter @ the end of the hose. I have a 2017 RGS with a 1suped up 124 (137 HP n 162 TQ). Was getting too much blow by for my liking. Without question, it drastically reduced the blow by issue. And what I also noticed was a lil more torque @ the lower RPMs (2,000 - 2,800)...Noticeably! I don't think You need it for stock (wasn't having blow by issues when RGS was stock). But if you have a big engine and are experiencing blow by, it should help. I'm also going to install DK's external breather.

 

So it increases power AND fixes bad rings? I need to check that out.