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  #11  
Old 4 Weeks Ago
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According to shanneba, current models have a 10 psi relief valve in the oil tank.
I haven't found (or really looked for yet) the relief in newer models.
But in keeping with the ops concerns, there is no relief in the 95 oil tank.

Quote:
Originally Posted by sportsterpaul View Post
My 2000 has a vent tube running up the backbone and out under the seat, it vents the tranny/primary. There had been a tech bulletin that addressed an issue of blow out from it. Seems it would sag causing oil vapor to pool in the sagged portion then when pressure would build it would spray out. Just saying it may not be crankcase related?
I haven't run across that bulletin yet but I can see the concern.
I still have plenty of them I haven't sifted thru yet though.
But does that bulletin mention anything about blowing primary oil into the engine?
Never say never I guess but it would seem to me the line would have to be pinched off to back up enough pressure to damage the seal between the cases.
That I'm not sure about. I guess it would depend on some things happening elsewhere also.

But normally (unless something is broken/cracked inside or crank seal is bad), primary oil stays between the primary/tranny and tranny vent.

And normally oil out the vent and into the A/C is attributed to bad umbrellas or excess CC pressure as Aaron posted.

If you replace the umbrellas (cheap fix) and the problem doesn't go away,
Then it starts getting more serious.
So frankly, that'd be the first thing to try.
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  #12  
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Hey guys! Thank you for all the info. I'm still pretty new to this stuff so I really appreciate all the help.

ASWRACING- I was not aware of the upgrades to the oil pump. I bought a used one from a 96 sporty and swapped it when I first had this problem but it made no difference. I might grab a 2007+ one and try again as, like you said, thats probably worth doing anyway.
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  #13  
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Also when I did the umbrella valves I was hoping that might be the case but they were in the right position (Top of the heads, closest to the air cleaner) I swapped them out anyway but they were still soft.
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  #14  
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Then this would be your next step I'd think.

Quote:
Originally Posted by aswracing View Post

Finally, if it's neither of those things, then you need to run a leak-down test.
You can do a compression test to find out if your engine is sealing OK.
Procedure with pics is here in the Sportsterpedia.
http://sportsterpedia.com/doku.php/t...:ref:svcproc20

The leakdown test will show where excess air is going.
And that is here:
http://sportsterpedia.com/doku.php/t...:ref:svcproc21

Question for aswracing.
What is the significance of moving straight to a leak-down test and bypassing the compression test?
Skipping the obvious?
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  #15  
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Bustert- I am starting to think from what you guys are saying it might be just that. Improper rings or installed improperly. I'm going to see if anyone has some in town here and if they do then maybe I will grab some rings and get the heads honed again. See what the leak down says first but start lining stuff up.

Hippysmack- Thanks for the links man. I have already done a compression test once when I got the bike and one just a couple weeks ago. Both times dry then wet....

Results from my latest compression test...

Dry
Front C - 175
Rear C -175

Wet
Front C -200
Rear C -220

I will hit the auto shop tomorrow and grab the tools to do a leak down test. I have a compressor and so will start with that asap.

Do you guys know if the gasket set I posted will work for my bike? I did not do the the 1200 kit so I'm not sure what was done inside and if that means different gaskets and what not. The local shops dont open here till tomorrow but I might see if anyone has a new set of rings and get my cylinders honed. Then I can cross that off the list as well.
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  #16  
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def not the hammer
the leak down will give a percentage, way more info that compression.
the bonus is that with the leak down is that you now have a way to find where the loss is at.
this can become more apparent on low compression setups.
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  #17  
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Quote:
Originally Posted by bustert View Post
def not the hammer
the leak down will give a percentage, way more info that compression.
the bonus is that with the leak down is that you now have a way to find where the loss is at.
this can become more apparent on low compression setups.
I always figured that if the compression test was good, ring problems weren't that bad either.
(since bad ring seal would throw the test)

You will have leakage with a leak down test either way.
But there is nothing wrong with doing it.

Quote:
Originally Posted by GasJunky View Post

Results from my latest compression test...

Dry
Front C - 175
Rear C -175

Wet
Front C -200
Rear C -220
Those numbers don't reach out and slap me.
That's kinda what I was talking about.
The leak down test will be a good fine tune.
With thoses numbers, is it possible to still have bad rings?

Quote:
Originally Posted by GasJunky View Post
However I have had a problem with it blowing oil out the breather tube under the seat since I bought it.

It only blows out when I'm on the hiway. It does not happen when I ride just around town.

Inside the oil tank the oil gets all bubbly and frothy and the oil it blows out the breather tube comes out all milky.
Sounds like classic wet sumping at high revs.
Doesn't do it putting around town.
There is a theory about the umbrellas getting weak but still working around high revs.
The umbrellas kinda float at a certain RPM allowing oil to escape the vents.
(more involved than that but just sayin')

The oil frothing happens to a lot of us at high revs.
With too much oil in the sump, the wheels churn it, air attaches to it and it's all sent to the tank.
The tank then separates the air/oil mix and the cycle begins all over.
So I'm wondering if you have a problem or our inherent CC pressure syndrome.
My theory is that these street bikes weren't designed for 100+ MPH on the highway sustained.

edit:
More about Why Oil Pukes Out the Breather Vent:
http://sportsterpedia.com/doku.php/t..._breather_vent

James Gaskets are fine as are Cometic and HD.

Last edited by Hippysmack; 4 Weeks Ago at 04:06..
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  #18  
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see you got your rubbers on, jumping in with both feet! but hey, this is how things get solved, knowledge is ever progressive.
numbers are theories anyway.
put in 100 psi and leak 20 psi so a 20% loss. compression 200 but have 180 insightful but not conclusive.
if you work on diesels, it is more about dynamic compression, aka, running.
cranking compression is just a relative number the mfg has come up with via design/testing and is used to determine if further investigation is necessary.
rings are dynamic and seals by dynamics. we all know about end gap but how many check lands. crappy land seating is more of an issue than end gap.
you can have good compression and poor oil control and vise-versa.
a big issue is with hd is when c/c pressures equalize, like putting a cork in a bottle and when this happens all depends upon dynamics and engine condition.
on the oil pump thingy, it must see c/c pressure or serious things can happen. if high c/c pressures exist and the pump is negative in relationship, the pump will vapor lock. the feed if it sees a negative pressure, it can aerate the oil (cavitation). the scavenge side will have issues also similar.
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I agree the numbers aren't conclusive but are relative.
And the results can be misleading from simply one test or variables changing within two tests.
And I know that dynamic results can vary from a static test.
Would bad ringlands also show up on a compression test?

OK,
Good compression from oil rising up to the rings.
But increased blowby during operation?
Geez, the more I learn the dumber I get.....
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Another consideration is the actual ring clearance within the groove. To achieve proper ring clearance, especially where the compression ring is concerned, the ring grooves must be smooth. This is because the ring drops to the bottom of the groove during the compression stroke, eventually sealing against the machined surface. During the power stroke, the piston moves down in the bore, causing the ring to up in the groove and seal against the top of the machined surface. A poor finish in the groove will not allow the ring to seal tightly and pressure will leak past the backside of the ring. The result will be excessive heat discoloration or carbon buildup in the land area between the top and second rings.

Production street engines often have clearances between .002 and .004 inches, but something like a race piston should never exceed a .002-inch vertical clearance. More vertical clearance will cause the ring to leak; less vertical clearance may cause the ring to seize within the groove. Keep in mind that a ring that can’t turn freely in the groove will not clean carbon out of the groove and will not be free to expand when combustion pressures enter the groove.
not sure for harley but some mfg actually put a positive taper to the ring land.
The overall diameter of the ring land in a common piston is smaller than the overall diameter of the piston, and in many cases, there is a small vertical taper. The reason for this size differential is that once the piston reaches top dead center, it rocks in the bore. If the piston ring land were the same diameter as the skirt, the rings would be required to handle the thrust load. The job of handling thrust loads is best left up to the piston skirt.

Something else you’ll hear about in relation to ring lands is “tilt.” Some (but not all) manufacturers machine the actual ring grooves with a positive “tilt.” This tilts the ring package upwards by a very small amount to help with ring seating.
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