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Old 12-03-2008, 02:35 PM   #1 (permalink)
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The Cure Vent / The Cure Vent Plus

Hello,

I'm installing new rocker box gaskets in my 1996 Electra Glide Standard that I bought about a year ago. The bike is stock, except for the jetting and the modified stock mufflers. It still has the stock air cleaner assembly, including the backing plate. I've never had a problem with any oil coming through the breather and into the air cleaner assembly. It's a well maintained, low mileage bike (less than 10K miles)

However, I might like to switch to a higher flowing air cleaner assembly like and S&S, Screamin Eagle or Ness. Is such a switch likely to increase the chances of oil from the breather system escaping / discharging onto the outside of the motor. That seemed to be the case with a friend's bike.

Should I install The Cure Vent or The Cure Vent Plus while I'm in the rocker boxes in anticipation of going to a higher flow air cleaner later?

Also, would it be better to not use the Plus version, but rather add some sort of check valve to the lines after the exit the heads to make the check valve serviceable without having to go into the rocker boxes?

I'm tempted to leave well enough alone, but I don't want to have to go back into the rocker boxes if I install a high flow air cleaner assembly soon.
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Old 12-03-2008, 03:36 PM   #2 (permalink)
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all i did with my 98 was put a K&N air filter in, , i dont knwo anything about the vent .
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Old 12-03-2008, 05:20 PM   #3 (permalink)
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Take those lines from the heads ....to the ground....you dont need anything on the line either...no check valves or any of that krap....the umbrella valve is already preventing any backflow of air.
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Old 12-03-2008, 05:32 PM   #4 (permalink)
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Crank vents function like a PCV valve. (positive crankcase venting)
They generate a partial vacuum in your engines crankcase to keep any seepage in the motor.
It also allows your engine to rev nicer since it isn't fighting itself when firing it's pistons back down into the cylinders.
They work and are used by most good wrenches when they are vacuum balancing a high performance motor.
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Old 12-03-2008, 05:36 PM   #5 (permalink)
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No..they dont work...not unless the oem umbrella valves are removed..crankvents are a scam ...and most engine builders know it...
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Old 12-03-2008, 07:56 PM   #6 (permalink)
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Tripl8 Knows What He's Talking About

The stock air cleaner doesn't flow much air at all. Upgrading you air cleaner will not have any effect on crankcase pressure.Upgrading your air cleaner with a zippers kit and dyna ignition will help a lot.Run the oil lines from the breather head ports right to the ground or to a catch can. DON"T USE CRANK VENTS!!!
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Old 12-03-2008, 09:18 PM   #7 (permalink)
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Quote:
Originally Posted by Tripl8 View Post
No..they dont work...not unless the oem umbrella valves are removed..crankvents are a scam ...and most engine builders know it...
They work you just don't know it. You shouldn't be feeding these people with false statements.
Anyone who knows how engines are built and run know that a partial vacuum is preferred in a 4 stroke engine. Case in point:
Any formula 1, Indy / champ car engine, Pro class hydros, etc.
always use a dry sump oiling system.
Whats a dry sump you ask?
That's a system where the pump design generates a vacuum in the crankcase to scavenge more effectively.
If you want a 4 stroke engine to run it's best and give major life to it's seals, generate a vacuum in the crankcase.
Go back to school and study a little more..
"Umbrella valves", sheech!
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Old 12-04-2008, 12:40 AM   #8 (permalink)
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The man has a stock motor not a hot rod. I make 100 hp with my 85" motor which is far from stock. Yep my heads are ported and massaged but still use umbrella valves. No hot rod Harley guy I know uses crank vents period. So if you want to waste money go ahead ain't my dough.
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Old 12-04-2008, 01:56 AM   #9 (permalink)
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I been routing the head breathers (using 3/8" ID hose) down & under carb I add a brass "T" fitting, that ties the 2 head hoses into one.
then route that behind the front pushrod tubes to underneath.

I route behind the front pushrod tubes because they are farthest away from cylinder...(so theres room)..
And if you locate the "T" in the right spot (behind the air cleaner), you never really notice the set-up & barely see the hose routing......

my .02
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Old 12-04-2008, 08:37 AM   #10 (permalink)
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Not to jump into a pissing contest, but race motors use dry sump systems to prevent oil starvation during extreme G manuvers, like cornering and accelerating. All your oil can slosh away from the pickup and your bearings go poof otherwise. A secondary advantage is a shallower oil pan, allowing you to lower the engine more.

I don't know what these crank vent systems are, but changing the air filter shouldn't have any effect on the engine venting, assuming you hook the hoses up like they were before. I don't have umbrella valves in my bikes, so I don't worry about that, but if I did, I'd do like Buddy Seat suggests. I have my vents running down to the ground.
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Old 12-05-2008, 08:59 AM   #11 (permalink)
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Obviously there are opinions on both sides but I have to say that the Cure Vent Plus kit works. I put these into the rocker boxes of my then-stock Evo about three years ago. I had experienced some oil out of the air cleaner after any appreciable time spent at freeway speeds. I have not had one drop in there since the Cure Vent Plus kit was installed. Since then I have installed SE heads, Andrews EV27 cam, and Arlen Ness Big Sucker backing plate and still no oil out the air cleaner.

I was told many times that Evo owners had long since enlarged the oil return hole in the middle rocker plate to help with oil out the air cleaner. After seeing how tiny that hole is, I can easily see how it could not possible allow enough oil to drain back out of the rocker boxes to keep from overflowing out into the air cleaner. The Cure kit provides a drill bit to enlarge the return hole. The ball check valve, the other part of the Cure Vent Plus kit, allows air to enter the rocker boxes through the breather tubes to allow the rocker boxes to drain (no vacuum) but doesn't allow oil out. True, you can instead, run a hose from the breather to the ground, but that just allows your pushed-out oil to escape the motor in a cleaner fashion and drip on the road--it doesn't prevent oil from escaping.

Anyway, all I know is that installing that kit stopped any oil from my air cleaner and I'm satisfied.
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Old 12-06-2008, 12:08 AM   #12 (permalink)
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Can't argue with success..Good for you.

I drill the return holes too..
But have to be careful on chromed ones, cause last thing anyone needs is chrome plating flaking off up in the
R boxes & possibly clogging up stuff..

Once ya drill you have opened the chrome, & it can flake off in time.. I seal it..& worries are over..


Friend has a S-glide evo that had a Hd chrome tranny cap added by Hd, but it leaked..

When I pulled the cap the underside was a nightmare, chrome peeling like the side of an old barn..
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Old 09-21-2009, 06:14 PM   #13 (permalink)
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Thumbs up

The "Cure Plus" is available from Johns Cycle Parts for about $30 with shipping, I'm installing it in my 98 FLHTCUI.

johnsmotorcycleparts.com
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