External Breathers and Catch Cans - The Only Reason to Buy

In this video, I discuss external breather systems and catch cans and the only reason why they would be truly needed.

[pk-teia]

The other day I did a 15k service on my 2018 M8 Road King, and the air cleaner was full of oil. I've been riding since 1978, and back then we had 2 stroke motors. It was allways a debate what amount of oil you should dial in on your oil mixer, and it often was hit and miss. Now adays we have 4 stroke engines in our bikes, and I understand that Harley has to build engines that comply with the epa regulations. But still, our engines are not ment to be burning oil. They never has been, and never will be. Therefore I am going to install a catch can to avoid all that crankcase oil mist being routed into my aircleaner/combustion chamber.

[thejerseyj]

Another benefit of external breathing is to prevent the hot air from the crankcase going to the intake. Harleys run hot as it is so venting that hot oily air into a catch can allows only cooler outside air going into the combustion chamber.
Also, oil will build up on your piston heads if not vented and will literally change your compression ratio and messing up your tune.

[Charger]

I’ve been building engines for over 50 years only about a half dozen Harley’s but to me it’s an engine and I do them all. The reason I go with external breathers is your combustion charge is much better without oil and in some cases moisture which I have seen many times. The only reason Harley doesn’t vent to the atmosphere anymore is because of the EPA plain and simple. They mandated all gasoline motor vehicles to have a pcv in the late 60’s. Before that engines had a breather on the end of a pipe sticking out of the manifold. The EPA is the reason we have so much trouble with vehicles today, diesels, gasoline cars and Harley’s. Too lean and when you tune them they run better. Well that’s my 3 cents, sorry it was so long. Love your videos. Don’t know if you’ll get it since it’s a year old but what the hell I thought I’d try.

[syyenergy]

I just installed an external breather after 36 years of not using one. The excess oil problem usually likely comes from overfilling the oil. In Florida, on really hot days, after a few hundred miles it's easy to slightly mis-judge how much oil you should have put in. The oil will expand more than you think sometimes.

[ryan_riffs]

Been workin as a bike tech on and off for 20 years and honestly don't see many catch cans in this realm but I did once own a twin turbo BMW and the aftermarket catch cans on that engine did a pretty amazing job at keeping the intake runners and valve stems clean over long periods of time. That was a twin turbo engine though.

[dieseljuice]

Thanks for the video, I'm not a mechanic, but did put a DK Catch Can on my 2012 Heritage. I think it looks cool under the stock air cleaner. I run Lucas Ethanol Treatment, and Lucas Fuel Treatment every fill up, so my top end should be clean anyway. Keep making your videos, thanks for all you do.

[thejerseyj]

DK Customs has been putting out a bunch of videos on this subject and they have done a ton of research to confirm that venting the crankcase air helps your bike run cooler and with more power.

[azadr]

Thank you for the video. It's good to hear different opinions on a topic. Most of us aren't mechanics and need to educate ourselves.

[frankburdi]

I'm glad you're talking about this all three of my Sportsters are external evented and my 2020 F150 has a high quality catch can and in about four thousand miles you can see the amount of oil it has stopped from going into the system

[alessandrovattolo]

The best explanation I've ever heard.

[barryleimkuehler]

Excellent discussion. One point not touched: the build up of the mist oil inside the throttle body, head and valves.

[bradlozano]

On my TC 103 i modified my SE stage 1 with a blowby bypass with a Filter not a catch can....I was getting a strong smell of burnt oil at operating temp when idling at stop lights....So i did that and put a Jagg oil cooler and it fixed the problem....No burnt oil smell and heating issues in the 100plus Cali heat anymore....

[duanehicks]

I just put a catch can on my 14 ultra but only because I got tired of cleaning the oil out of the air filter at every service I hope it makes it easier to maintain.

[jamesborck]

Finally found a video explaining why breathers are on a bike been wanting to know everything about Harley cause I do the little maintenance things like fluid changes and air filters but I see weird stuff that aren’t on cars so it throws me off

[timothyweiss]

Thanks for the good info on a much debated topic. Thanks

[usmcvet]

I put one on my stock twin cam, along with the DK customs O2 sensor Vied's. I just wanted to cool the motor down, which it did. Runs great now, not melting my thighs in the summer. Made my own with flexible fuel line, hose clamps, and a pod filter. Routed it under the motor, pretty cheap.

[freebehindbars]

I put catch cans on everything everything. I’ve seen a new RGS with 3k have carbon covering the tops of both pistons. Just not sure why someone wouldn’t do it?

[Enter-a-name]

I run an oil catch can on my 2001 Buell. It was vented to the atmosphere from factory. They ran the vent tube up under the seat and it ended right above the rear tire. Every once in a while after a spirited ride, I would park the bike and come back to an oil spot on my tire. Nothing to be alarmed about, just a bad place for the vent. So I run a catch can near the battery. I vent the engine and also the transmission to the catch can. No more oil spots anywhere.

[dmenaced]

Really kool video. I like that frame effect. Good info too!

[Alliwantedwasapepsi]

Good explanation to counter the claptrap I watched from DK. High detergent fuel should cancel any problematic carbon build up. As well as good highway runs.