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-   -   Sportster Crankcase Pressure / Engine Breathing / Wetsumping and Mods (http://xlforum.net/forums/showthread.php?t=2073932)

60Gunner 2nd August 2019 17:12

I didn't assume anything. He said his rings were shot. If that's the case and the blowby isn't coming out the breather bolts, it's a fairly educated guess it's being blown past bad guide seals since they were defective in the first place and he's never replaced them. He's more or less confirmed this by the carbon build up in the combustion chamber.

The size of the hole in the bolts can make that much of a difference. I'd be willing to bet just as many are running aftermarket bolts with the bigger holes than are running the stock ones since the first thing people do is get better ACs and vent externally. I haven't seen aftermarket bolts with small holes. I could be wrong.

If my oil wasn't getting to the pump, it would be pumping my tank full of bubbles. Which isvwhat was happening with too much pressure and oil not returning. Evident by my leaks. The krankvent stops these leaks by maintaining a constant pressure or slight vacuum and thats a claim I do buy. Too many claims of leaks disappearing to not buy it.
Whether it be slight pressure or slight vacuum, I think it does a much better job at maintaining a constant. Too much up and down with the pressure with the stock breathers for whatever reason and it's just not necessary. That's my theory anyway.

60Gunner 2nd August 2019 17:24

Quote:

Originally Posted by bustert (Post 5767169)
if the evo is anything like the iron, porting the short intake makes little of anything and it has been said that the rough surface helps with gas mix. the exh makes more sense.
if you ever run an iron with the breather miss timed, there will be a notable diff as rpm goes up, pretty sure the evo will respond like/kind.

You're right to an extent. Tho there are a few places in the intake port that would be better opened up. Wedge sent me diagrams detailing this and what he did as I intend to do a little home porting this winter.
But yes, intake rough for the turbulence(Not intake manifold tho), exhaust smooth.

60Gunner 2nd August 2019 17:32

Quote:

Originally Posted by Tomcatt (Post 5767135)
And not having any rotating parts (and windage) in the heads slinging oil around. It's relatively calm up there with limited oil flow plus the OE breathers do act as separators. It's really not a bad place to put breathers.

There's a fair amount of oil but you're right about it not being flung around. My breather gauze was saturated but then I'm not sure how much excess oil was sitting in mine due the excessive crankcase pressure.

Hippysmack 2nd August 2019 17:52

Quote:

Originally Posted by 60Gunner (Post 5767175)
I didn't assume anything. He said his rings were shot.

If my oil wasn't getting to the pump, it would be pumping my tank full of bubbles.

My apology's, I must have missed that somewhere.
I am having trouble getting away at the moment.
But I fired mine up and got the oil temp to about 140F, pulled the cap and the engine died.
Fired it up with the cap off and it would idle, just a little rough.
So it's not the fact of the cap being off that kills the engine.
It's a sudden pulling of the cap that does.

I also watched inside for froth with the cap off.
At idle, a thin layer forms on top of the oil.
Pulled the throttle to 3000 RPM and the froth disappeared.
Back to idle, the froth came back.

I tried to get a short video with my camera but that didn't work out.

Four Speed 2nd August 2019 18:04

Quote:

And not having any rotating parts (and windage) in the heads slinging oil around. It's relatively calm up there with limited oil flow plus the OE breathers do act as separators. It's really not a bad place to put breathers.
I go the other way on where to site it as I prefer the breather to be near the pistons to be able cap the considerable pressure
pulses on an engine that has one crankpin. Hence I suspect a head breather will maintain a higher average CC pressure if
all els se is equal and both systems have fresh umbrella valves. The other down point is the heat which we seem accept ages
the elastomer umbrella valve in the heads. The two points in its favour might be less oil mist in the rockers but that is why crankcase
mounted breather have oil baffles and less visible hoses.

Four Speed 2nd August 2019 18:06

Quote:

pulled the cap and the engine died & Back to idle, the froth came back.
Oh dear, that sounds serious Hippysmack:sofa

Hippysmack 2nd August 2019 18:27

Hahaha..
I'm just analyzing, not worried.
I didn't have it to operating temp either.

edit:
I tested pulling the oil cap back to back with the A/C off and then on.
Keep in mind, the oil cap off is allowing CC pressure to escape and atmosphere to enter the engine.
A/C on, I get lower RPM and light froth only at idle.
A/C off, I get no response difference I could notice but bubbles and froth at idle.
I may be goosing the throttle too much to get the temps up though.

I'll add, the froth is Not raising oil temp as I have yet to get the temps over 140F.
(big fan on the motor)

dieselvette 2nd August 2019 19:29

Quote:

Originally Posted by Hippysmack (Post 5767190)
Hahaha..
I'm just analyzing, not worried.
I didn't have it to operating temp either.

edit:
I tested pulling the oil cap back to back with the A/C off and then on.
Keep in mind, the oil cap off is allowing CC pressure to escape and atmosphere to enter the engine.
A/C on, I get lower RPM and light froth only at idle.
A/C off, I get no response difference I could notice but bubbles and froth at idle.
I may be goosing the throttle too much to get the temps up though.

I'll add, the froth is Not raising oil temp as I have yet to get the temps over 140F.
(big fan on the motor)

Have you done a compression or cylinder leakdown test lately?

Hippysmack 2nd August 2019 19:36

Did both about a month ago.
Didn't write the results down (need to start doing that) but they were both good.
Actually I wrote them on a piece of cardboard and can't find it. :o

60Gunner 2nd August 2019 19:58

You might be getting crankcase pressure/oil past you guides too.

On 2nd thought, what carb are you running? And aren't you venting to the AC?


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