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[Twolanerider]

Have just completed a top end rebuild on the red bike.  The "Buttonfly Resurrection" to remove those things that were the Zippers abortion from the bike and make it right once more. 

All signs so far suggest the bike will run great.  Praise be to the Travel Gods.  Finished a roughly 80 mile run with it this afternoon that was its first real run since the reassembly was completed.

Have one small issue yet to deal with.  Not even an unexpected issue.  Just want to "vent" (sorry about that) a few thoughts while fresh on my mind right now.

The Zippers build made a mess all over the bike with blow by out the heads.  Added Doherty Myst Free kits inside the rocker boxes and Doherty PowerVent outside the heads in incremental attempts to ease up the mess.  Nothing ever helped.  Finally just plumbed a catch/drain line down between the cylinders and then down in front of the motor before turning rearward to dump the oil behind the bike.  Between burning oil in a rear cylinder that never seated and blow by out the front it used a quart in just under a thousand miles. 

I assumed the current build would not completely get rid of it.  Am now using the TP Pro Vent rocker boxes.  Trade press and recommendation from others all seem to suggest they handle oil at the atmospheric vents better than anything else out there.  I don't expect it to ever completely go away though as one corner I cut was keeping the Zippers 50 mm throttle body. 

It's the only Zippers part still on the bike.  It's intake flange does not accept any breather assembly other than their own.   And their own in now way vents the heads.  So the head vents are always completely open.  Any little of oil or vapor that might re-become oil has to run out in the open and drip down on the motor.

After this 80 mile run, the last 50 of which done mostly at cruise, I got home to find five drops of oil back behind the vents, on top of the tranny or wherever else it might fall.  It's not a big mess like before.  The very small droplets aren't even necessarily a big deal.  But I think I'd like to pursue options to just finish cleaning it up.

Would still like to avoid spending the several hundred bucks necessary to just throw away this otherwise ok throttle body, intake and breather.  I'll next put the Doherty PowerVent back on and see if adding that tiny bit of backpressure will keep more drops in the motor.

If that doesn't do it (as I don't expect it completely do) I'm thinking about simply closing the system.  Making up a flexible braided line kit that connects between the two head vents on top and then drops down to the vent line that goes in the oil fill neck.  Any oil residue from the head vents then just goes right back in the oil bag.

My question to those more informed than myself is will closing that system increase crankcase pressures in some way that should not be done?  Looking at how the vent system in the rocker boxes work it does not seem so.  So I don't know if the OE system is open to atmospheric pressure (whether left open or plumbed through the breather) only because it's easy/cheaper/convenient to do it that way or if it must be vented completely.  Would prefer not to solve one tiny little oil drip issue at the expnse of blowing a rocker box seal or puking the oil cap/dipstick out going down the road.

[vagabond6542]

Have just completed a top end rebuild on the red bike.  The "Buttonfly Resurrection" to remove those things that were the Zippers abortion from the bike and make it right once more. 

All signs so far suggest the bike will run great.  Praise be to the Travel Gods.  Finished a roughly 80 mile run with it this afternoon that was its first real run since the reassembly was completed.

Have one small issue yet to deal with.  Not even an unexpected issue.  Just want to "vent" (sorry about that) a few thoughts while fresh on my mind right now.

The Zippers build made a mess all over the bike with blow by out the heads.  Added Doherty Myst Free kits inside the rocker boxes and Doherty PowerVent outside the heads in incremental attempts to ease up the mess.  Nothing ever helped.  Finally just plumbed a catch/drain line down between the cylinders and then down in front of the motor before turning rearward to dump the oil behind the bike.  Between burning oil in a rear cylinder that never seated and blow by out the front it used a quart in just under a thousand miles. 

I assumed the current build would not completely get rid of it.  Am now using the TP Pro Vent rocker boxes.  Trade press and recommendation from others all seem to suggest they handle oil at the atmospheric vents better than anything else out there.  I don't expect it to ever completely go away though as one corner I cut was keeping the Zippers 50 mm throttle body. 

It's the only Zippers part still on the bike.  It's intake flange does not accept any breather assembly other than their own.   And their own in now way vents the heads.  So the head vents are always completely open.  Any little of oil or vapor that might re-become oil has to run out in the open and drip down on the motor.

After this 80 mile run, the last 50 of which done mostly at cruise, I got home to find five drops of oil back behind the vents, on top of the tranny or wherever else it might fall.  It's not a big mess like before.  The very small droplets aren't even necessarily a big deal.  But I think I'd like to pursue options to just finish cleaning it up.

Would still like to avoid spending the several hundred bucks necessary to just throw away this otherwise ok throttle body, intake and breather.  I'll next put the Doherty PowerVent back on and see if adding that tiny bit of backpressure will keep more drops in the motor.

If that doesn't do it (as I don't expect it completely do) I'm thinking about simply closing the system.  Making up a flexible braided line kit that connects between the two head vents on top and then drops down to the vent line that goes in the oil fill neck.  Any oil residue from the head vents then just goes right back in the oil bag.

My question to those more informed than myself is will closing that system increase crankcase pressures in some way that should not be done?  Looking at how the vent system in the rocker boxes work it does not seem so.  So I don't know if the OE system is open to atmospheric pressure (whether left open or plumbed through the breather) only because it's easy/cheaper/convenient to do it that way or if it must be vented completely.  Would prefer not to solve one tiny little oil drip issue at the expnse of blowing a rocker box seal or puking the oil cap/dipstick out going down the road.

I can only answer your question from experience I once had with an aircooled 6 cylinder on a 1965 Corvair.
They had just started the recycling of the oil vapors back then. I thought that it was causing too much carburetor problems and block it.  I learned the hard way, the vent is necessary. I think the Harley engine has to vent the oil vapor to somewhere due to design. Most likely it would be the aircleaner or opening of the throttle body.
This is the best I can offer. Hope it was helpful.

[Midnight Rider]

Don, I've often thought of the same exact thing...install a tee in the line and pipe the head vents into the tee.  There must be a reason not to do it, but I'd like to know why not 

[Twolanerider]

Don, I've often thought of the same exact thing...install a tee in the line and pipe the head vents into the tee.  There must be a reason not to do it, but I'd like to know why not 

TC, as Vagabond mentions above there are reasons you shouldn't.  It'll build up crankcase pressure inside a system and something will have to give someplace.  Would be the same thing on the standard system on our bikes.  On an OE system doing it could actually cause a dry sump.  Very bad news.

With these ProVent rocker boxes I thought there was an alternative though.  In fact I was mistaken.  I was misreading a design page on one of the rocker boxes and realize now what I thought was a check valve in each box that could allow what we're describing in fact is not.  So for purposes of this discussion the change in rocker boxes didn't change that part of the equation.  My bad.

However....

If necessary we could still accomplish the same thing.  Just in a slightly different way. 

Do the same thing.  Make up a flexible line to replace the current oil line going in to the fill neck.  Mount to the head vents any of the many nipples or tubes to give yourself a place to route a line from (I've already got that since the Zippers air cleaner doesn't use the head vents).

In the flexible line going to the filler neck have a T fitting sticking up rather than a single line fitting.  One fitting will plumb to the head vents catching everything running "downhill" to it.  Vented oil then just goes right back in the oil pan. 

On the other side of the T route a vent hose.  Run it up the inside of the frame.  Lots of places to hide it there.  Hang a little filter on the end of it to be extra careful.  It will vent to atmosphere.  You won't need much.  The oil itself won't run "uphill" along this line.  Only the vented pressure will.

If mine actually has blowby that needs to be dealt with that's what I'll do.  Before it gets that far have simpler options to try first though.  Will go ahead and hang that Doherty external breather back on.  It might help a little.  Probably won't.  But it can't hurt to try it.  Most likely thing to have some positive impact will be just let the oil go down a bit though.  It's sitting here at 1/4 qt low warm.  1/2 qt is common for these things to find their "happy place."  So, if I'm lucky, a little less oil in the bag might help.

[Twolanerider]

Just a bit of clarification.  After a few phone calls and a couple of messages I obviously didn't do a good job of describing the current "problem" to begin with. 

Am just chasing details now.  These Pro Vent rocker boxes really do seem to be much better.

As is I've got nothing other than a nipple hanging off the head vents.  When it was that way before riding a hundred miles made a mess.  A MESS.  The Doherty MystFrees slowed it down.  But only a bit.  The external Doherty vents didn't seen to make any difference at all.  It was such a pain in the ass that eventually I just ran a line from the vents and dumped the drips down under the bike.  Just like the old days.

While I'm still in "tinker mode" after the reassembly is as good a time as any to deal with anything I might.  The same run I made today, without anything to keep the vented oil off the motor or side of the bike, would have made a decent mess before.  With these ProVent rocker boxes I had four or five tiny drops to wipe off things.  No other vented spray or other mess.  It ain't bad now. 

A little less oil in the bag might all but solve it.  The external vent breather to add a tiny bit of back pressure might all but solve it.  If nothing does I can always run a line like before and just let it piddle beneath the bike.  Or I might do the new plumbing as described above.  But right now just thinking out loud about options while still in the state of mind to tinker.  Because once the weather gets good and stays good I don't plan to tinker anymore .

[hd-dude]

Don;
Why not plumb the head bolt vents back into the AC backplate?

[Twolanerider]

Don;
Why not plumb the head bolt vents back into the AC backplate?

Well.....  I thought about it. This Zippers backplate doesn't make that an ideal option.  Do-able though.  It is one of the options on the plate if this turns in to an issue.  My personal biggest hesitation is I'm just not fond of routing the oil back through the intake charge.

I know, EPA guidance has had the stock stuff doing that precisely that for years.  It would certainly be the most well hidden solution.  I'm just hoping that after I find where the engine's happy spot for oil volume is, and after it's been run enough to have fully settled in that it'll be enough of a non-issue I won't have to.

[hd-dude]

Most aftermarket back plates do this as well. It seems to work well unless you have excessive blowby then your element can get pretty messy. I have to wonder why you have so much to begin with? You have the Fueling plate and pump if I remember correctly? Something to check if you have not already is the vent tube between the crank case and the oil filler. Be sure its clear.

The other thing that can be done is go back to the stock oil pump and plate, use the Baisley spring in the plate to keep the pressure up equivelent to the Fueling. Then add the S&S reed valve in behind the pump. These work very well to eliminate blowby. I had used them successfully in bikes that have had the problem. The drawback to it is it is not compatable with the fueling pump. (I am sure that some will disagree with me but the fueling pump and plate are a bit overated anyway)

[Twolanerider]

Most aftermarket back plates do this as well. It seems to work well unless you have excessive blowby then your element can get pretty messy. I have to wonder why you have so much to begin with? You have the Fueling plate and pump if I remember correctly? Something to check if you have not already is the vent tube between the crank case and the oil filler. Be sure its clear.

The other thing that can be done is go back to the stock oil pump and plate, use the Baisley spring in the plate to keep the pressure up equivelent to the Fueling. Then add the S&S reed valve in behind the pump. These work very well to eliminate blowby. I had used them successfully in bikes that have had the problem. The drawback to it is it is not compatable with the fueling pump. (I am sure that some will disagree with me but the fueling pump and plate are a bit overated anyway)

Actually had incremental steps to let me believe it's not an oil pump/spring/plate issue. 

The Feuling pump, lifters, plate all went in with the 575 cam install.  And ran fine without anything but the rarest drop coming out.  The blowby came later when the rest of the Zippers top end went on. 

It was an annoying mess too.  Nothing helped much.  And I tried almost everything.  Finally just ran a line down to get it under the bike.

There was no way I'd have intentionally routed that prior discharge volume in to the intake charge.  After this combination finishes sorting itself out for a few hundred miles I'll decide specifically what to do. 

If 80 miles produces only the tiny amount of discharge I saw today though I'd have little reservation about just tapping a new hole in the air cleaner backplate and routing it there.  Just a little gun shy from the last mess and want to make sure this time that it's something much closer to the normal non-problem before doing that or anything else.

[Unbalanced]

Don,

Before I pulled the Zippers off the roadking I was running the the harley stage 1 back plate, later Zippers released their back plate.   I put it on the bike so that I could use the extra wide filter that cracked and fell apart.   

From there we ran a hose to the backplate to push the blowby into the intake.  I did this because I didnt want to build a puke can and I didn't want to try and route a hose that would drop the oil off by the swingarm since the oil can then blow on to your tire as well was well as everywhere else.   I didnt want to clean off oil after every ride since the oil was getting everywhere with this method which is why i opted to put it to the back plate.

fwiw, I was told not drill into the intake itself, as this creates a vacuum and will suck additional oil out.   
 

[Twolanerider]

Don,

Before I pulled the Zippers off the roadking I was running the the harley stage 1 back plate, later Zippers released their back plate.   I put it on the bike so that I could use the extra wide filter that cracked and fell apart.   

From there we ran a hose to the backplate to push the blowby into the intake.  I did this because I didnt want to build a puke can and I didn't want to try and route a hose that would drop the oil off by the swingarm since the oil can then blow on to your tire as well was well as everywhere else.   I didnt want to clean off oil after every ride since the oil was getting everywhere with this method which is why i opted to put it to the back plate.

fwiw, I was told not drill into the intake itself, as this creates a vacuum and will suck additional oil out.   
 

Thanks Harry.  On the prior build I had eventually ran a hose and dropped it down at the rear of the bike just to keep the mess off.  I didn't want to screw with building a catchcan for it either.

So far, with only small miles, I'm optimistic that the huge mess isn't going to be there this time.  That being so it'll be even easier to keep the potential small drips handled.  I'd never have routed the old discharge in to the intake as you describe.  Would have created a Carbon Generation Machine.  With the small bit I'm seeing now though it is a potential solution that could also be neat and mostly well hidden.  Definitely not in the intake though.  Only want to catch what comes out on it's own.  Not suck more out that wouldn't have made it's way outside the engine to begin with.

[Talon]

Are you still having a problem with that back cylinder? If the back is allowing blow by this could cause high crank case pressure, much higher than normal. In turn you would get more pressure and oil venting out your breather. The breather is to release pressure from the case, it pulses with the movement of the pistons. If you could build a catch can with some type of breather at the top, then you could plum it back to the vent tube. But you need to allow it to breath, if you just plum it back into the system, the pressure will also be forced back in and would probably push out you oil cap! If the rear cylinder is still a problem, I'd get it fixed, this could be the majority of the problem with the vent.

[Talon]

Something along the lines of this, The vent line would go into one of the top two fittings, and the other top fittings would need to be open or on a breather filter, the bottom fitting could be plumbed into the existing vent line. This isn't exact, but gives you an idea of that I was saying, you wouldn't need the sight tube on the side. The mist would go into the can, most would condense, the pressure would be allowed to escape, and from the bottom fitting the oil could return into the system. The question is how big would it need to be and where could you hide it? this one is for a car.

[dejavo]

Twolaner
The oil is sometimes the problem. More and more proof is surfacing that synthetic oil can cause the rings to loose the seal. I have personally seen it proved on the dyno. Without any disassembly at all the shop flushed the syn and used fossil, then heat set the rings onthe dyno. Compression etc went up considerably. I had the same done on mine even tho the munbers were good they got a lot better.
Ring seal bad = blowby
I am back to fossil in Harleys

[vagabond6542]

Twolaner
The oil is sometimes the problem. More and more proof is surfacing that synthetic oil can cause the rings to loose the seal. I have personally seen it proved on the dyno. Without any disassembly at all the shop flushed the syn and used fossil, then heat set the rings onthe dyno. Compression etc went up considerably. I had the same done on mine even tho the munbers were good they got a lot better.
Ring seal bad = blowby
I am back to fossil in Harleys

Twolaner,
I can agree with mrootberg  to a certain degree.  It would depend on how many miles are on the engine.
Before synthetic came out to be the oil of choice, fossil was all that could be gotten.
The real issue would be did the rings seat themselves in the cylinders. And that depended on the ring make up and who made them.  The average seating mileage use to be around 5000 miles, otherwise there would be blowby to be experienced. Thereby creating a great deal of pressure, the rest  you know about.
If it is only vapor you are dealing with, feeding behind the A/C through the back plate would be a good idea.
If there is oil along with the vapor, a PCV valve would be a good addition to the vent line. This could keep the throttle body free of oil. There are quite a few scenarios that can be apply to this situation.
I hope I am helpful with this.

Vag

[Twolanerider]

Are you still having a problem with that back cylinder? If the back is allowing blow by this could cause high crank case pressure, much higher than normal. In turn you would get more pressure and oil venting out your breather. The breather is to release pressure from the case, it pulses with the movement of the pistons. If you could build a catch can with some type of breather at the top, then you could plum it back to the vent tube. But you need to allow it to breath, if you just plum it back into the system, the pressure will also be forced back in and would probably push out you oil cap! If the rear cylinder is still a problem, I'd get it fixed, this could be the majority of the problem with the vent.

Talon, I don't know that I'm having any real problem right now.  The conversation was speculative to begin with.  If there is anything it appears to be minimal now.  As with everything else will not prejudge any of it until it's had a chance to run more and see a wider temperature range.  So far, however, isn't too bad.

[Twolanerider]

Twolaner,
I can agree with mrootberg  to a certain degree.  It would depend on how many miles are on the engine.
Before synthetic came out to be the oil of choice, fossil was all that could be gotten.
The real issue would be did the rings seat themselves in the cylinders. And that depended on the ring make up and who made them.  The average seating mileage use to be around 5000 miles, otherwise there would be blowby to be experienced. Thereby creating a great deal of pressure, the rest  you know about.
If it is only vapor you are dealing with, feeding behind the A/C through the back plate would be a good idea.
If there is oil along with the vapor, a PCV valve would be a good addition to the vent line. This could keep the throttle body free of oil. There are quite a few scenarios that can be apply to this situation.
I hope I am helpful with this.

Vag

No friendly suggestion is ever unhelpful Vag.  The new top end has only 100 miles or so now.  The questions at the onset of this thread were speculative coming from the prior history of the engine and more general possibilities.  It needs to run a bit before I do anything.  Having the various ideas in hand to weigh against behaviors that may manifest is never a bad thing though.