The Sportster and Buell Motorcycle Forum - The XLFORUM®

The Sportster and Buell Motorcycle Forum - The XLFORUM® (
-   Sportster Motorcycle - Bottom End (
-   -   Sportster Crankcase Pressure / Engine Breathing / Wetsumping and Mods (

60Gunner 27th July 2019 22:22

That was pretty close to the exhaust port and thev only place I got over 300. Everywhere else on the head was 280ish

From what I've read head temps in the 380s are normal from head temp sensors on a hard run. Much over 400F and you need to check your afr.

60Gunner 27th July 2019 22:30

Head temp and oil temp are 2 different things Hippy. Head temps are always higher. 320 is actually low for head temp after a hard pull.

dieselvette 27th July 2019 22:40

Just did a quick comparison of new vs. 15-yr old stock breather valves by mouth pressure.
Visually, they are exactly the same in every way. Probably still using the same molds to make them.
First - blowing into the old ones, I would say they work perfectly. The slightest whisp of air pushes it open, and you can blow tons of flow through it. The slightest reversal of flow and it sealed 100% shut. I don't see how it could be any faster.
Then - the new ones. I would have said the old ones are fine, without new ones for side-by-side comparison. The new ones are apparently more flexible, and seem to open "farther" with less air. They also seem to be faster response on closing.
Feeling the rubber tit sticking out, the old ones' rubber is just a tiny bit more stiff.

The differences are barely perceivable, so for your average Joe this test is too subjective.

So, if I ever get my heads back from the indy I'll start by running the new breathers and get things broke in & tuned up. Then, for posterity, I could switch to the old ones and see if the perform differently. After that I'm interested in aftermarket, or maybe not.

To be clear, I'm not trying to put it up against the Krankvent (we all know it's superior ha). What I want to know is if my old ones had truly failed or not. Again, for posterity.

dieselvette 27th July 2019 22:44


Originally Posted by Hippysmack (Post 5765654)
What's the best way to test a displacement pump?

Run it at max rated pressure (and no more!!!) measure the flow and see if it meets spec. If you can't get to max rated pressure, pump is shot.

60Gunner 27th July 2019 22:49

I could blow thru one breather hose and the air came out the other.
Personally, I could care less if anyone switched to a krankvent. I know what it did for my motor. Even if they work the same, being able to run them externally and take them apart for cleaning or replacing the umbrella alone is worth it and in my case, move it to a more desireable location.
That said, the stock ones DO let air back in even when new.

dieselvette 27th July 2019 22:51

1 Attachment(s)
Hippy seems to be interested in oil expulsion. Here is a picture of the foam. You can kinda see how it's layered from top-to-bottom from more dense, to less dense.

(As-installed the less-dense would be toward the umbrella).

Also worth a look is the orange seal - not sure how this could possibly fail, but if it did that would bypass the "anti-reverse" valve.

Edit: I suppose the plastic housing at the orange seal could become warped, thereby compromising the seal.

Tomcatt 27th July 2019 22:52


Originally Posted by Hippysmack (Post 5765650)
You are correct about a brand new displacement pump.
But what happens when you get scratches from debris in that pump?

It may pump a little less but it's still a positive displacement pump and the point I was making still stands. Adding two piston squirters doesn't increase oil flow into the engine. In simple terms the squirters just steal a little flow that would have gone elsewhere but the total is still the same.

Look at it this way.You have a positive displacement pump pumping pumping 20 gal per minute at 3,000 shaft rpm. Just an example. you can have 5 outlets delivering 4 gal per minute or 4 delivering 5 gal per minute, the pump doesn't care it just mindlessly pumps 20 gal per minute.

60Gunner 27th July 2019 22:56

Hear ya go Hippy.

And yes, the plastic housing of the stock umbrellas does warp. Mine did. And what did they cost?

dieselvette 27th July 2019 23:22


Originally Posted by 60Gunner (Post 5765668)
That said, the stock ones DO let air back in even when new.

I suppose that's could be true, but I just don't see how it's possible. Are you saying that would be the case with all, or just if it's defective or worn?

60Gunner 27th July 2019 23:29

According to people in that link, 380° is in the realm of normal. Even 400° but much higher and it's probably running lean.

322° is low but that's pointing an infrared at it from the outside too. Had it an inch away tho and oil temp was right there but on the cooler side too. 230° is acceptable there. I'll see how close the infrared is tomorrow in comparison to a probe stuck in the oil.
If those are anywhere near accurate, and I believe they are, those are good temps.
Going to shoot some boiling water.

All times are GMT +1. The time now is 10:47.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2023, vBulletin Solutions Inc.
XL Forum® - Linson Media LLC