Breather pipe R/R

[mcdonnell7511]

I want to replace the breather pipe on my 1966 R69S with a new pipe. Can a member tell me the DIY how to...?
Thanks, Jack

[schrader7032]

When you find out, let me know! Actually, I am missing the breather pipe on my R25/2 and bought a new one from Vech. Unfortunately, the OD of the pipe is bigger than the ID of the hole in the engine case. I've also been told by Richard at Vech's that there is a small stacking pin that is supposed to hold the pipe in place. I can see the small end of some kind of pin but I don't have anything small enough to pound against it. I think the pin goes through the outside casing and into a hole that's buried on the internal part of the case. I don't think I can move the pin that direction.

See this picture...#13 and 14:

http://www.realoem.com/bmw/showparts.do ... g=11&fg=10

What I've been thinking about is grinding the OD of the pin such that it will slip fit inside the engine hole. What I'm afraid of the pipe not staying in place. I supposed I could make it an interference fit and freeze the pipe before inserting it. But then, if that interference fit is too much, it could crack the case.

So, I'm stuck. For now, I'm waiting to figure out what to do.

[mcdonnell7511]

Kurt,
Now you know why I'am asking! I see the pin; but how do you remove the pin to release the pipe?

[schrader7032]

Jack -

I'm as stuck as you are! I don't have anything small enough or stiff enough to push the pin in. But I don't think that would help either. And the hole in the bottom of the case is too small to get anything up in there to try and push the pin out. If the pin could be extracted enough to get a grip on it, it could be pulled completely out.

So, I really don't have a clue. I've this on the back burner for my R25/2. But I have an idea. I'm going to pose the question to a German forum for single cylinders that I hang out in. They've been pretty helpful so far. Maybe they'll have some ideas.

More later...hopefully.

[schrader7032]

Jack -

I got some input from the forum in Germany...they've been pretty helpful so far. I guess with so few singles making it to the US, there's a lot of them over there.

Here's what I asked:

"- the outside diameter of the new pipe is slightly larger than the inside diameter of the opening in the case. I've thought about griding the new pipe or taking off enough so that there is an interference fit with the case. Then I could freeze the pipe and quickly fit it in place. I think I need to be careful with too much interference in case the new pipe might split the case. Is this a way to go?"

The response I got was:

"Yes Kurt, that's the way. You can also heat the case up to about 100°C. You won't ever crack the case, don't worry about that.

There is a small conical pin with a diameter of about 2.5mm inside the case, which should normally bar the pipe from moving out of the case. Try to beat it with a mandrel through the hole in that way that the pin falls out.

For correct installation of a new breather pipe stick the pipe with "ice and flame" and adjust it in the right position. Then try to bore a new hole into the pipe through the bore for the pin. It's a bit tricky. Don't be angry with yourself, if it doesn't fit - you're not the first one"


I'm still not sure how to get that pin out. I don't see how it can be driven towards the bike...I don't think it has an exit on the other side. I'll have to look a bit closer.

[mcdonnell7511]

Kurt,
I made some calls and all I heard was "we never replace that part", but I'll keep asking.
I'am somewhat surprised that R/R information about this wear item part is not freely at hand...!
Nevertheless, what I think we could consider is to cut the old pipe close to the case and force the pin out from the inside to pull the head out. Then deal with the new pipe install as you suggested above.
Jack

[mcdonnell7511]

Kurt,
Use a small punch (2 mm) or smaller to push out the pin from the front to release the pin.
Jack

[schrader7032]

Jack -

What doesn't make sense is that I can't see the backside of where the pin is going to go. IIRC, the backside is buried in the engine case. Maybe there's a difference between a /2 and my R25/2. Maybe I'll have to look at my two bikes and see if the placement of the pin is any different.

It seems the difficulty will be to get the new pin to through through 4 items - front and back of the engine case and both sides of the pipe. It's been suggesed to get the new pipe in place and then line ream with a drill bit. Then come through with a new pin, maybe even an oversized pin.

Someone said to know worry so much about the pin and just use something like red loctite to hold the pipe in place.

[Darryl.Richman]

I think Jack has it right. The pipe was not intended to be replaced routinely. If the case was being cleaned (or blasted), the pipe would be cleaned at the same time. If it was damaged, then it could be cut off and the pin removed by pushing it forward with a needlenose pliers or some equivalent.

I would go at it with a Dremel cutoff wheel as close to the case as possible and push the pin out from inside what was left of the breather pipe. Then I would place the new pipe and the pin back in place with Loctite green (bearing lock).

[schrader7032]

and the pin removed by pushing it forward with a needlenose pliers or some equivalent.

I'm not seeing this. When I was last looking, I didn't see how I could get anything up that small hole and still be able to grab the exposed part of the pin. Seems like by the time I get the needle nose pliers up there, the taper of the pliers would have closed the jaws of the pliers so that I couldn't grasp the pin. Let alone, being able to squeeze hard enough to move the pin at all.

When I get back down on the floor, I'll check this out.