Hello all. I've done as much research as I can possibly do and cannot find an answer to this. Perhaps someone here can. Just installed a K&N RK-3910-1 air filter to keep my stock look. Tuned with Power Commander 5 and it runs like a top. No issues there with decal pops or anything. What surprised me is that I didn't see any reduction in temperature (oil). No big deal as I'm using synthetic oil. What I'm wondering is if anyone has installed an External breather system on the K&N filter system. I can't find a reason why K&N eliminates the external filter and keeps the internal breather system. Would seem to me that the external breather would be better. Any inputs on this. I noticed that DK custom sells an external breather kit. Wondering if that would be counter productive to my K&N filter. Hope this all makes sense. I working with a 2008 Twin Cam. Pretty much stock.

 

You wont see any temp drops, it'll breath better. Run it like your set up before adding that external bypass.
Is the intake burning a lot of oil? Maybe something simple as running a 1/4 quart oil less fix that.

 

K&N is just selling filter kits that comply to EPA standards. External venting is not EPA appoved without a filter.

 

I figured that they had to be EPA. Just wondering if I could benefit in anyway by adding an external breather kit to it. And no, I'm not having any oil burning or any side effects at all. But I've been seeing a lot of posts about external breathing being much better. Just trying to figure if it's wort the 40 something bucks to do the mod. Just want my bike to run longer and stay healthy lol.

 

In my opinion, you absolutely should add the external breather system. Ever see the nasty crap that goes back into the motor??? DK Customs has some great products and info for this simple mod.

 

Thank you Boogieman. I'm leaning that way. It's actually one of the least expensive mods out there lol.

 

I have them on my bikes and they have worked flawlessly. Depending on what type of backing plate you are running, it may be as simple as changing out the breather bolts, adding the necessary hoses and catch can, filter or just run it down to the bottom of the bike. Here is a pic of what comes out of the motor and into the can. You can see it’s nasty stuff.

 

If that’s the question the answer is YES, keep the oil out of the air/fuel mixture. This will reduce carbon buildup

 

Definitely external breather/s. Keep all that blow-by crap out of the intake.