Breather mod

[solg]

I am planning a complete fireball rebuild.I have a 2008 iron barrel that has a little wart where the engine breather should be. I noticed our host has engine cases for sale. If They have the right year engine case would it be a lot of doings to swap out their case for mine.my plan would be to make it possible to get the engine breather mod in the process?

[ERC]

Why not use the case you have?   ERC

[ace.cafe]

We have converted several 2008 cases to the old breather, and some individuals have also converted theirs.
The method is fairly simple.
Just drill a 7/16" hole where the breather is supposed to be, and then tap it with a 1/4" pipe thread tap, and use a 1/4" pipe thread fitting in the case to attach the elbow fitting.
Works fine.

Just contact me when you are planning to actually do this, so that I can give you some tech support during the process.

[ERC]

The only problem is there is very little wall clearance in this area. less than a 1/4". The system they use on the later motors is very similar to what can be done to a 700cc twin cylinder to make them more oil tight and breathe better. I would think you would be fine plugging the hole on the timing side of the crankcase and putting a duckbill on the stock breather coming out of the oil tank.  ERC

[edthetermite]

I did it to my 08 Iron Barrel during last winter's rebuild. A Dremel tool is handy to dress the inside of the case where the pipe fitting penetrates. Get the appropriate tap and just take your time.

[solg]

I was just thinking that if there were engine cases available for $150 that would work out better than my 08 it might be cheaper in the long run. Just a thought. Turns out I will be modifying my. As the one I was looking at was for a 350 cc.
Now I'm wondering if it wouldn't be better to have an elbow welded in place. It would have to be a clean weld but I'm shure it would be more stable than a threaded in piece.  This may be a case of diminishing returns though.

[Arizoni]

IMO, welding on an unknown aluminum alloy is dangerous.
If the aluminum is a permanent mold (or die) casting welding is definitely out of the question.  The alloys used and internal structure of the casting can result in major damage.

Likewise, welding cast iron is very difficult.

[solg]

You think the cases are made of a different material than my 79 Bonnie ?

[Arizoni]

I really don't know about your Triumph.
Its crankcase may be a sand or investment casting.
Either of these processes allows the use of better grades of aluminum and those methods of casting result in much higher integrity than a die or low pressure permanent mold casting.

[barenekd]

The old English casting were real solid aluminum. hey were easily weldable. He Japanese stuff that was coming out then was very pourous, although you couldn't tell it from the outside.. It was essentially unweldable. Most of the late model bikes are made out of this crap. I don't know what the Enfields are using or when they might've changed processes. I have seen a broken one yet. But it would seem likely that it is the unweldable stuff!
Bare

[Arizoni]

Back in the days when I was the Quality Assurance engineer assigned to the Engineering Department, the chief Manufacturing Engineer talked them into making some of a production Auxiliary Power Units aluminum housings using a low pressure Permanent Mold process.
He had worked at Mcculloch Chain Saw where most of their engine parts were either die castings or low Pressure Permanent Mold castings.  He maintained this change was supposed to save the company millions of dollars.
After spending a fortune to make the dies and to test the new parts they were put into production.

One day I was called into the Chief Engineer's office.  Laying on his desk was one of these housings.
He said, "Jim, your QA department says this is a good part.  What do you have to say about it?"

I said, "If it passed inspection, it's a good part."

He said, "We were going to install the screw thread inserts into it but one of our mechanics refused to do it.  Take a look into the threaded holes and tell me if he was justified in his refusal."

I looked down into the holes and saw good threads running about .150" (3.8mm) deep.  The majority of the rest of the threaded holes consisted of sponge like metal  with an occasional bit of threaded solid metal. 
Needless to say, the part was junked and the company had to spend another small fortune recalling the engines that had been shipped with these LPM parts.
The LPM parts were replaced with old fashioned sand cast parts.

I'm not saying that LPM and die cast parts can't be useful.  In their place, they can be strong enough to work quite well but they do have some problems.  Welding them is one.