Oil transfer valve?

[xlfan]

Does anyone know the purpose and function for this valve located inside primary @ crankcase wall on 59 to 76 Sportsters?

xlfan

[Lew]

Good question.  From what I understand, it's designed to allow oil from the primary to the engine if the primary oil level gets too high from the early style (leaky) sprocket shaft seal.  The oil would be sucked to the sump and returned back into the oil tank.  Obviously not a good idea if running different oils in the engine and primary.  Most rebuilders block it off as it's not critical with today's modern style seals.

[xlfan]

Thanks alot Lew  That solved a decades old mindboggling question my head have had spinning 

xlfan

[nibroc]

just had my '59XLCH blocked off and sealed--have to vent the primary/tranny now!--looking for a 5/16" hollow bolt--found a 3/8" hollow one but want a 5/16--anybody got one?

[eglideic]

 Harley used a hollow bolt on the rear motor mount.
34744-77

[nibroc]

Harley used a hollow bolt on the rear motor mount.
34744-77

  yeah...that was a 3/8" bolt--looking for a 5/16" one

[xlfan]

Isn't it a through hole on one of the rear motormounts of pre-77 cases?

Would it be fair to say that a .060'' hole is sufficient for pressure equalizing primary/transmission case?


xlfan

[eglideic]

Harley used a hollow bolt on the rear motor mount.
34744-77

  yeah...that was a 3/8" bolt--looking for a 5/16" one

Why don't you just use the 3/8 one and put it where the Mo/Co wants it used?
I'm one of those old school bikers that trust the Motor Company more than God.

[nibroc]

Harley used a hollow bolt on the rear motor mount.
34744-77

  yeah...that was a 3/8" bolt--looking for a 5/16" one

   
Why don't you just use the 3/8 one and put it where the Mo/Co wants it used?
I'm one of those old school bikers that trust the Motor Company more than God.

   EGLIDE---because i have a 5/16 tapped in top of primary for vent which is not part of the rear motor mount bolting

[eglideic]

Harley used a hollow bolt on the rear motor mount.
34744-77

  yeah...that was a 3/8" bolt--looking for a 5/16" one

   
Why don't you just use the 3/8 one and put it where the Mo/Co wants it used?
I'm one of those old school bikers that trust the Motor Company more than God.

   EGLIDE---because i have a 5/16 tapped in top of primary for vent which is not part of the rear motor mount bolting

Well that was a mistake, wasn't it?
You should use the stock vent set up just like God and the Motor Company intended.

[xlfan]

As far as I understood, that hollow bolt and motor mount didn't come into play until -77, pre -77 was vented through the oil transfer valve. Did the earlier crankcases have a through hole in any of the rear motormount boltholes?

[eglideic]

As far as I understood, that hollow bolt and motor mount didn't come into play until -77, pre -77 was vented through the oil transfer valve. Did the earlier crankcases have a through hole in any of the rear motormount boltholes?

All it takes is a drill.
If it doesn't have one, it can in less than 5 minutes.

[saltcaveminer]

im at work but i was wondering if the xlch oil tank lower bracket bolt hole (3/8) could be used for a vent?  Salty

[wheelie1239]

Lew is correct this is a one way valve that allows the primary case to breathe into the crankcase.

I have a 71 xlh that when the valve failed it allowed oil from the motor side into the primary. The motor oil caused the clutch plates to swell. This caused clutch creep. Had to hold her in place with my feet when stopped and sometimes it was not easy. Put in new clutch plates and it was ok for about a month. Then the clutch creep came back. Also noticed that the oil level was rising in primary and it smelled like motor oil. Looked into replacing the one way valve. Could not budge it, probably original equipment. There is a special tool for this but it did not help. Welded a 1" nut to it. The heat helped to break it loose. Plus the leverage that I could put on the 1" nut with the breaker bar was greater.
Replaced the valve and clutch plates one more time and no more clutch creep since! Took me a while to figure out why I had clutch creep no matter what I did. Hopefully this will help somebody else that has the same clutch creep issue. I took it to 2 well known indy shops and they could not fix it. Glad I was able to fiqure it out, I now have a 2 finger clutch...