From down in the rabbit hole

[jOe]

April Fool's day comes early?


http://www.ebay.com/itm/1954-Harley-Dav ... fZ&vxp=mtr

[thefrenchowl]

Not the 1st time I saw that type of mod... And it's an early 54 set, siphon tube and no transfer valve...



I am fond of mods, but this might be a step to far!!!

Patrick

[sportsterpaul]

Wow, I guess if its the only way you can stay on a Harley as your knee blows out, I guess there enough cases out there to butcher.

Sorry to be ignorant-- what do you mean by "siphon tube"?

[DaveC]

The long lost K Model ultimate performance mod is finally revealed. Who would have thought it would be a few more HP from an electric starter.

[thefrenchowl]

Hi Paul,

Before the days of the proper lip oil seal that sits behind the crank sprocket and the one way valve in mid 54....

...there was the K set up: a weird O ring seal with 2 brass washers with 3 ears on each behind the sprocket that allowed a lot of oil to go from crank to primary.

So there was a siphon tube mounted on the special hollow bottom bolt of the chain adjuster...
It sucked up excess oil up to its opening when pistons went up and vaccumed, maintaining the right level in the primary...

Interesting these old Ks... Ehhh!!!

Patrick

[JerrryR]

Hi All,
Patrick is this the set up your referring to with regards to the syphon tube and does it look correct? It's on my 54KHK I'm trying to get together. While I have the floor I want to thank all of you for all the great insights, tech tips, how to do stuff etc. You guys are a wealth of information and I know I'll be trying to pick your brains on motor stuff in the months to come. I'm not much of a mechanic and was hesitant about attempting engine work myself but have now decided I'll give it a go. What I think pushed me to this point are the comments a couple of you made on a thread a couple months back where you said,(I'm paraphrasing), "give it a try, all you can do is screw it up and have to do it all over again". So with those words of encouragement I'm underway.
Thanks to all again and have a great day,
JerryR, want a be mechanic

PS. Can somebody please provide a cheat sheet of answers for the website questions we always have to answer. I'm tired of always getting them wrong. What kick does a CH start on? Mine varies.

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[sportsterpaul]

Oh wow, that is interesting. That thru-hole on the primary chain adjuster boss always bothered me. I tell people do not use silicone there, there is not that much oil that can weep either way down the threads, but I had no idea they used it as an oil return from the primary to the engine. I knew enough to not use too long a bolt on the primary chain adjuster, I wonder if any hacks have pinched the flywheel with a long bolt? I am ashamed to say I have a 1952 engine sitting here I need to start working on, so I should be able to see this very setup. I have never gotten into anything earlier than a 1962.

I guess the other part of this is that the primary had no vent to the outside, in the fill cap, right? So that means the primary would pump down to crankcase average pressure, which I am sure they wanted to be negative.

The original Harley engineers loved to use pulsating crankcase pressure to move oil about. I understand the really early (1920s) engines used positive crankcase pressure to blow oil up to the top end. Taking the whole timed breather out in 1977 and later Sportsters caused a lot of grief. I think it was the late 1990s before they let the Buell guy showed them they needed a huge scavenge pump to keep crankcase pressure negative.

When I was in the auto business, I got schooled about how good negative crankcase pressure is. I asked an engineer about it-- and he tossed me the Parker Hannifin Seal Handbook. It explained that it is nearly impossible to make a seal work across both positive and negative pressure. An O-ring will "pump" from one side of the groove to the other, letting a little oil or fluid by every time. A lip seal is designed for pressure in on direction only. Since I was a young know-it-all, I told him we could used two lip seals, facing each other. He pointed out the Seal Handbook where people have tried that, in hydraulic cylinders. What happens is that the pressure builds up between the two seals, to tens of thousands of PSI, until the seals rupture, or it can damage the piston or cylinder.

That was one of the major botches of the 1977 case redesign. They were on a cost-reduction binge, and figured to get rid of that expensive timed breather. But when they put a check valve in the breather tube, well all that does is let the gearcase and crankcase go from a little above zero as it exhausts to negative as the check valve closes. Its the scavenge pump that tries to keep the pressure negative, and a small pump still lets the crankcase pressure get awful close to zero (gauge-- meaning same as outside air pressure). A little blow-by past the rings, and now the whole engine is going across zero pressure every crank stroke, no wonder they all leak.

Gosh, as I was typing this, JerryR posted, and Dave's, great software shows his post above my preview-- too cool, thanks for those great pictures Jerry, I hope I have all that stuff in my 1952.

[thefrenchowl]

Aouchhh!!! Jerry!!!

The syphon tube normally sucks from behind the sprocket!!!

So the curve out of the bolt is much tighter.

I remember it from the bottom bolt, can't be sure now!!! Check the parts book tonite!!!

But I can't remember where the little bracket screws on...

it's a long time I had my KK in bits, it's been gone (for a better home, Tom ; - ) ? ) for 13 years now...

I suppose you can adapt the proper oil seal and holder, it'll keep the crankcase oil out of the primary...

Cheers from patrick

[hennesse]

Jerry,

Take lots of photos/dimensions of the tube - mine is missing, and I'll have to make one. I have the 25111-53 bolt and valve, but not the actual tube.

The parts book does show it going in the lower hole - and that's where mine is. But the parts book doesn't show the alignment.

make shore the valve behind the tube where it bolts in is in correct suction side faces in it will go in either way.

How can you tell which side is suction side? My valve has one side with a small hole, one side with a large hole.
Then there's a copper washer.

Dave

[55khkjoe]

Jerry, my 53 KK had the siphon on the bottom bolt hole with tube towards bottom of primary, which amazingly does not allow for the 2 pc chain tensioner. I believe the the extra support came in 54 or 55. I can see why early cases blew when the shoe part of the adjuster would bend down with hard riding thats why they added the brace on the adjuster I believe. Not exactly sure.