Crankcase Vent Pressure
Thread Starter
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Seasoned HDF Member
Joined: Jan 2013
Posts: 10,637
Likes: 1,246
From: Lake, Ms
Mike I'm really running out of ideas and the Dealer isn't much help either. Trying my best to figure this out on my own. No mods done to the bike except for the Stage 1. Sent my custom map to Dynojet for analysis and everything was good with that. I haven't been in one of these engines yet so I'm not 100% sure how the vents work but it's not Rocket Science. I'm sure it works similar to a PCV valve on a car. The puzzling part to me is the bike performs excellently other than what I've described. Seems to reason that if there was excessive crankcase pressure it would be even more so at higher rpms and performance would be hampered which is not the case. Just can't figure this one out.
2010 Limited with some stuff
2010 Limited with some stuff
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
if you look at a parts manual (or the ronnies partsfinder website) you'll see how the venting works.
HD is on about the 4th version since head breathers came in 92.
I've never had trouble, even the '95 went over 80,000 miles
they are simple umbrella valves, like a pcv they allow the fumes to flow out.
the reason they are at the top of the motor is to allow the oil to separate from teh air (most of it)
mike
HD is on about the 4th version since head breathers came in 92.
I've never had trouble, even the '95 went over 80,000 miles
they are simple umbrella valves, like a pcv they allow the fumes to flow out.
the reason they are at the top of the motor is to allow the oil to separate from teh air (most of it)
mike
Thread Starter
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Seasoned HDF Member
Joined: Jan 2013
Posts: 10,637
Likes: 1,246
From: Lake, Ms
I'll definitely give that a look.
Not knocking this site or anyone in particular because I have learned a great deal from its use, but it seems to me that the more technical the question or problem is there are way fewer people to respond. If this were an oil thread or a handlebar thread folks would be all over it giving their 2˘. Not fussing really, just don't understand why more people aren't willing to help.
And Mike...thanks again. You've always helped when needed.
2010 Limited with some stuff
Not knocking this site or anyone in particular because I have learned a great deal from its use, but it seems to me that the more technical the question or problem is there are way fewer people to respond. If this were an oil thread or a handlebar thread folks would be all over it giving their 2˘. Not fussing really, just don't understand why more people aren't willing to help.
And Mike...thanks again. You've always helped when needed.
2010 Limited with some stuff
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
complex problems require an interest, experience or aptitude with complex issues.
there are certainly areas that i stay away from as my experience only goes so far- and my training is generally automotive- so often theory/ analysis. ( I don't build motors- i have a Pal who does it all day, every day)
but I do have a mind for trivia and am pretty good at remembering changes in models from the '36 OHV up
oil and handlebar threads are good, it's the "gateway".
common mistakes are dumping tranny instead of oil, busting the front brake light switch and confusing foot pounds for inch pounds.
oh and suing HD because the rider didn't check air pressure.
Once a newbie gets past these they may develop an interest in big issues.
Let's see if someone else can jump on this thread with a cogent idea- but try a foot over the muffler tip
mike
there are certainly areas that i stay away from as my experience only goes so far- and my training is generally automotive- so often theory/ analysis. ( I don't build motors- i have a Pal who does it all day, every day)
but I do have a mind for trivia and am pretty good at remembering changes in models from the '36 OHV up
oil and handlebar threads are good, it's the "gateway".
common mistakes are dumping tranny instead of oil, busting the front brake light switch and confusing foot pounds for inch pounds.
oh and suing HD because the rider didn't check air pressure.
Once a newbie gets past these they may develop an interest in big issues.
Let's see if someone else can jump on this thread with a cogent idea- but try a foot over the muffler tip
mike
Last edited by mkguitar; Aug 1, 2014 at 02:23 PM.
Road Master
Joined: Jul 2012
Posts: 876
Likes: 65
From: CT
Here is my 2 cents. You said you were down a quart after 700 miles and you are blowing smoke out of your rear cylinder pipe. I bet you just can't see the smoke hauling azz down the road. Any way you are burning up in the rear cylinder. ...why? Try the compression test again with the piston in a different position. ..none the less I bet you are blowing oil by the rings.
Thread Starter
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Seasoned HDF Member
Joined: Jan 2013
Posts: 10,637
Likes: 1,246
From: Lake, Ms
Here is my 2 cents. You said you were down a quart after 700 miles and you are blowing smoke out of your rear cylinder pipe. I bet you just can't see the smoke hauling azz down the road. Any way you are burning up in the rear cylinder. ...why? Try the compression test again with the piston in a different position. ..none the less I bet you are blowing oil by the rings.
Also to add to this...I do have a really strong oil smell when riding.
2010 Limited with some stuff
Thread Starter
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Seasoned HDF Member
Joined: Jan 2013
Posts: 10,637
Likes: 1,246
From: Lake, Ms
Here's a couple of videos. The first shows the stumble at idle.
This one shows the smoke after extended idle when hot.
2010 Limited with some stuff
This one shows the smoke after extended idle when hot.
2010 Limited with some stuff
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Grand HDF Member
Joined: Dec 2007
Posts: 4,999
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From: Bay Area
Why dont you try venting your breathers to the air and see if your consumption goes away. Another thing is Im thinking guide seals, although its a lot of work but remove the exhaust pipes and look at the valve stems, if its the seals there will be a trail of burnt oil on the stems and backside of the valve.