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#87201
The c/c venting to the oil tank makes sense. I’ve thankfully not had to strip my engine that far so haven’t had the chance to check. It would be interesting to know how that works. However, surely that would tend to hold back the return from the timing case. Maybe that is why the level in the tank drops quickly and there is so much oil in the timing side.
#87207
The problem with this system is that the oil emulsion condenses in the long rubber tube from the top of the oil reservoir and begins to restrict it (I had to use white spirit and a small paintbrush to clean mine out yesterday). The catch can was only half full of white "jelly". I can tell when this needs doing because the bike begins to hesitate and smoke a little after a short time at idle.

On another engine I've worked on I fitted a breather pipe from the crankcase to the rocker cover (on that engine there was a problem with excess oil pooling in the head casting) and run a separate breather pipe from the rocker cover to a catch can (the latter being a mandatory requirement for track work).
#87208
Paul fitted a breather to the inlet rocker box on asbo 30 (not sure if he fitted it on the others)

There's no problem with emulsion build up

On my Harley I am running open breathers (well hollow bolts with foam held with gauze) it used to run them to the air filter and gunk up the air filter and inlet
Now no problem at all I did buy the catch can conversion in case the open breathers dripped too much but they don't

Sorry for going off topic Dai
#87212
Daiwiskers wrote:
Sat Jan 11, 2020 12:01 pm
Paul fitted a breather to the inlet rocker box on asbo 30 (not sure if he fitted it on the others)

There's no problem with emulsion build up
Sorry for going off topic Dai
It is very easy to make and fit a rocker box breather - I have done a few, using nothing more than the valve stem from an old inner tube. Remove the valve core after cutting the stem out of the tube, drill a suitable sized hole in one of the rocker boxes - the exhaust one is a good place, as there is more heat there to help 'steam off' any condensation, although it will look neater from the inlet rocker cover while still doing a good job, and push the stem through from inside, then fit the securing nut as you would in a wheel. Slip a suitable length / diameter piece of tubing over the stem and route it to wherever you want. Get a good fit and you won't even need to clamp it on the stem, as the threads will keep it held firmly in place.
Attachments
Asbo Bullet 350 005.jpg
#87214
I've no concerns how to make and physically fit a breather, but only if it should be done; I can't really fathom the logic of RE never fitting one as standard.

Michael Waller's video rather clouded the issue in my mind because it seems on early bikes the oil in the timing case needed pumping to the tank via the idler pinions working in conjunction with the "dam wall" in the casting, rather than relying on overflow and gravity.

I still think the best way is to run the oil tank breather direct to the rear chain and discard the catch can altogether, just like on my old BSAs, to reduce the run of the pipework where condensation can occur. I have bought a one way valve to go in the pipe, to prevent any road dirt or water getting sucked back in.
#87223
Daiwhiskers, TexasChris et al.
I note two separate discussions have essentially combined focussing on the breather.

My 1996 535cc enfield originally breathed through its crankcase breather stub. That had an ID of 6.25mm. And at any revs above ~3000 it was inadequate so oil wept out of every weak joint. I enlarged it, drilling it out step-by-step eventually to 9.5mm ID (leaving some 2mm wall thickness) and cleaned up the rough casting inside the crankcase and now it is effective up to a sustained 4000rpm. Any higher and oil vapour again weeps from wherever it can.
I tried the Hitchcocks gearbox ‘tower’ and found it made things worse by adding pressure to the gearbox which helped the leaks. So I went back to the tried-and-tested OEM vent – but I need a better solution.
I note the modern 535 has a breather ID of (I think) 15mm. Is that how large it needs to be to control the oil? And I’d fit one of those if I could find a suitable place. I like the idea of rockerbox breathers, though.

I note the rocker box breather in Paul’s image comes off the exhaust rocker whilst DaiWhiskers indicates his is off the inlet rocker – like Adrian’s in the image. Does its position make a significant difference?
Cheers, ChrisD
#87227
TexasChris I'm sorry

All please note I have started a thread on engine breathing to avoid going off topic any more

ChrisD

Head over to the engine breather thread to be honest it sounds like you are suffering from blow by, buy ,past,
(spelling don't laugh the easy words are the hardest)

Sorry again both Dai

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