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Just showing off my new breather seyup. My Mikuni filter was warped. No bueno.
Sorry their blurry, bike was idling lol.
Got rid of idle cable. Modified mine. For crank breather I soldered a brass barbed fitting to the filter.
Dragtron 2 breather. Drag specialties bracket and tube. Trask Mikuni CV adaapter
Last edited by Fblo1690; Jul 13, 2018 at 03:51 PM.
Looks good! I did mine a few years ago when I seemed to be having excessive oil blow into the air filter! I routed mine thru my Doherty Power Vents(out of business now) to a hose tee and into a single hose over my trans to the LH side of the bike to a catch can that I got on eBay. Of course after doing all this the oil blow bye problem has gone away!
Many use a downward gravity system that is surely gonna exentuate flow. That IMO will cause more loss of oil during a periodic oil change scheduele
I prefer having the hose point north of the breathers.
this still allows the crank to breathe as it likes, with out the loss of oil
I thought once the oil is out of the heads, it’s out for good? Aren’t there reed valves or something preventing it’s return? Or is that only on my twin cams?
I modified my S&S stealth AC the same way as all my other bikes - tapped hose barb under the standoff’s, plugged the channels to the intake with JB weld and red oil resistant Loctite secured set screws, hoses to a dual nipple mini filter directly under the intake. The EVO is the only bike that’s NEVER leaked a DROP of oil. My Twin cams used to **** it out until I started keeping my oil lever just under half dipstick. Now they’re pretty dry as well. Only some condensation during the winter months.
I’ve never given it a second thought. And as far as I know, four strokes don’t rely on Reed valves.
But if you really wanna know? , a simple test might answer your question.
I think the crank vent is a by pass and not restricted by a one way valve, therefore, oil that is blown out, should return to where it came from if previsions to allow it was provided.
In this case, a simple system that uses gravity to allow a constant movement would suffice. But remember... The main objective for the breather valves which are nothing more than drilled out bolts is to allow air to escape the cranck in order to avoid a build of pressure that would reap havok if blocked off.
So a filter must be fitted that is attached by two hoses that are ultemetly affixed to the breather bolts must be mounted above the heads. This completes the gravity effect so that the crank can do its thing and allow for hot oil, condensation minus hot hair to return back into the engine.
This by the way will not hurt the motor in any way based off by the seat of my shorts assumption.
i at one point rigged a home made version of this that I eventually replaced by a Wimmer custom made product... https://www.wimmercustomcycle.com/5-...xternal-ch.php
I use this kit as intended by Wimmer specifications. But, if I wanted, or needed to allow a gavity effect, all I would need to do is reverse the position of the two filters.
But since I barely notice much oil in the sponges fitted to the kit. I just let it drain out. I check for sediment occasionally. All I notice is mostly water and some oil. I would estimate a ratio of 10-1 measure by drops.
I hear some bikes puke much more. My sporty with fitted with D&K breather bolts never shows any blow by of any kind. YMMV
Hope this helps anyone out.
Evo's use an Umbrella valve and TC's use a reed valve. Both are check valves that do not allow atmospheric air back into the motor. They are a one way check valve..
Evo's use an Umbrella valve and TC's use a reed valve. Both are check valves that do not allow atmospheric air back into the motor. They are a one way check valve..
my 92 is a bottom breather, does it have the umbrella valves?. Just curious.
my 92 is a bottom breather, does it have the umbrella valves?. Just curious.
I know the early EVOs were a crank case breather system and HD changed it at some point to head breather system but I dont know the year they did this. I sure someone with the knowledge will chide in shortly. Umbrella vavles were used with the head breathers only that I know of. Does your heads have a bolt on the side just above the air cleaner?
Good machined cylinder bores with known working umbrella valves, you can put those hoses in your boots. Run my hoses to the ground and may of gotten a drop hit the ground after 7 hard years with the 89", the current big cube high compression engine doesn't even have hoses off the head turn downs and not a drop of oil on the engine in 4 years, give credit to the the guy that does my cylinder boring.
If you are spewing oil out the breather system with a top breather, repair the base problem and not mask it, the money saved from not buying gizmo's can replace hardened umbrella valves plus get the hoses out of the back of the air filter plate, eating your own chit is for chickens, not engines.
The OP's breather system is right, may offend a few tree huggers but a Harley is built to De-EPA and make it better.
Last edited by 1997bagger; Jul 15, 2018 at 05:58 PM.
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New breather setup
