A50 crankcase breather

[Andy Edwards]

Hello. I am hoping to improve the "Designed in" oil leak on my 1962 A50.  I have tapped the breather outlet to 1/8" BSP, and intend running a pipe or hose from there over the gearbox mainshaft boss and out through the rear engine mounting plates.  The only decent hose that I can get to fit is 1/4" R6 oil hose.  My concern with this is that this could be too small a bore size that might create excessive back pressure.  Does anyone have a view on this?  My preferred option is to use a copper or "Bundy" pipe.  I've tried to fit 8mm O/D tube without success as I cannot get an 8mm compression fitting into the limited space available.  Again, I wonder if this size of tube would create excessive back pressure, so would not want to try to fit smaller tubing.  Am I being over cautious and over thinking this?

[Mike Farmer]

 

I went down this line a few months back and in truth "Gave up" for all the reasons that you have stated.

I had considered blocking the existing out let and then re routing by drilling a hole nearer the casing. halfway up the out let.

The way I looked at it I always came up with the back pressure and possible blockage problem. Which would of course remain so unless the pipe is taken downward.

I have another set of cases on the bench at the moment and am going to give that a try. I had considered running a pipe up into the air filter to actually suck it clear but that could get to look ugly.

Unless it is routed into the oil tank or air intake, it will just move the leak to another point. (spray it onto the rear tyre could work but a bit dubious??)

Still thinking.....I'll keep you upsides with ANY progress

Mike

[DAVE BRADY]

Hi,

I do not think that the last time this was discussed there was a conclusion.  If all is well in the engine then there should not be any oil coming out of this breather.  A bit of oil mist at the most, perhaps when the engine is quite hot, which could perhaps be directed towards the chain.  As the breather will only emit the oil mist when the engine is running and for the most part when the bike is moving, this will take any oil away and help keep the chain moist.
Out of interest I have a high mileage A65 and after standing for several weeks it wet sumps.  On starting the engine there is lot of smoke out of the exhaust but nothing comes out of the breather.
On the other hand my wife's A10 is the opposite.  Again high mileage, clean exhaust but dribbles from the breather.

Dave.

[Andy Edwards]

Hi Mike / Dave. Thanks for the feedback.  Maybe I'll just leave things as they are.  The engine should be good having had a rebore and new pistons/rings along with the SRM crankshaft end feed mod.

[Mike Farmer]

 

My conclusion is the same. With a good oil pump and sound PRV it should not wet sump unduly. and a newly rebuilt motor should be fine from this aspect.

So in truth I doubt that I'll revisit this. I dont really think it would be time well spent. Guess I'll just keep thinking about it.

Mike

[chaz]

many Japanese and others, Chinese even Enfields, route the breathers into the air box. its a way for the manufacturers to meet emissions regulations, so why not old Brits. It wasnt a worry back in production days but now could be a good arguing point for keeping classics on the road, also a fairly easy conversion, they use flexible pipe .

[ChrisG]

This is how I did mine. A bit convoluted but the only way to get it to point rearwards so I could attach a flex pipe to it.

[Mike Farmer]

 

Thats good. Its about what I decided not to do. But I have one on the bench that I'll now maybe have another go with.

Mike

[Mike Farmer]

 

Hi

At tyhe point where you have fitted the "square headed" part. Is that straight into the existing outlet or did you need to cut it back to give you the working space/clearance.

Mike