When I first bought my bike oil carry over was no problem. Then the rings got seated and the weather got hot. Now, I am getting oil carry over on every ride. Have already thrown away the original air filter. After cleaning it a few times it was so oil soaked it was worthless. Lots of others are reporting issues. One member had his umbrella valves replaced and it made no difference. Harley better not have a problem, warrant wise, with people venting to atmosphere. Because we shouldn't be expected to buy new air filters every 3k miles.

 

I'm wondering of some of these issues with different models aren't a result of the terminating end of the vent tubes not being positioned far enough into the inlet of the throttle body. Thus the upstream accumulating oil vapors drip into the breather before it can get sucked into the intake. Just a theory as I haven't visually seen all of the tubing configurations on the different models. I know that mine has a factory tee joining the two tubes together with a single outlet into the throttle body inlet. In other words ,maybe a short extension of the tubes might remedy what is accumulating in the breather.

 

You might very well be right. But it appears to me the M8 breathers are not up to the job. I owned 4 TC bikes and never had enough oil carry over to give it a second thought. My bike is a 114 with the stock ventilator air cleaner. The stock hose location is not ideal.

 

 

 

Maybe you or you dealer could simply try extending the end of the tubes say ,1/2" or so and see if the accumulation rate changes. It couldn't hurt. What complicates the trouble shooting scenario is that it seems that not all bikes of the same model and configuration are experiencing this dreaded symptom. Are you having to add more engine oil that normal to maintain acceptable dipstick level?

 

Manual says clean the filter every 5000. I've heard Harley techs say do it every 1500. Personally, I've added a small canister inline with vents. In the canister, I've used a foam fuel filter for a lawn mower. The canister slows down the air because of the larger cross section, and the filter does a good job pulling out the oil. Mostly on race bikes. Essentially a fuel filter would work too. Just have to make sure any condensate drains down.

 

 

Same here. No more oily snot on my saddlebag and side cover.

 

Yes, don't want this crap going into your engine.



Getting it out increases performance, helps with cooling, and increases engine longevity.

LINK to external breather systems for Twin Cam and M8 engines.