Occasionally I have noticed a little oil in air filter when cleaning , clearly it would get sucked into the throttle body aiding in carbon build up, so was wondering are external breathers a worthy fix? Easy enough to do by bypassing the holes in cleaner backing plate with a couple of 1/8 BSP barbed hose fitting tapped into the housing , bit of hose running off. Whats your thoughts ? anyone ever heard of continuing to let this oil get sucked in harms the engine? who`s got one ? would like some comments cheers.

I'm running one.

I went with a DK Customs 606, it's 5.5 inches like a lot of others out there so can change faceplates easy.

Ran a sort of horseshoe arrangement with a filter at the bottom, after approx 2000km's nothing substantial has blown out of it, I make a point to run my oil halfway on the dipstick to help.

The stock heavy breather when I took it off had a fair bit of milky residue (oil/water vapour) in the intake runner.

marginally less oil in sump is sumfin I will try .thanks for  response 

truth be know I probably overfill sometimes when servicing cheers

I have one on the EVO. Just a cheap breather I got off Ebay. I fitted it as I did not like the idea of any shit being directed to the intake area. Once it was fitted I simply sealed the backing plate hole with a nut/bolt/washers.

Ive seen a few different types fitted , just wondering if necessary or merely a preference

Where the tee is I just ran a 6mm vacuum hose under the tank, under the seat and down next to the fuel tank breather venting to the floor.

Do a search of the internet. There is plenty of info that points to carbon build up on the top of pistons is from the sump venting back into the motor.I put one on my wideglide and notice there is a bit of oil that comes out of it but I always make sure the sump is full, I might drop the oil level as suggested and see what happens.

just reading my owners manual { 2012 road king} says oil capacity should be 4 Quarts or 3.79 litres with filter .well stuff me Ive be overfilling