Tappet Cover Breather.

[Bob White]

I would like to install a breather in the tappet cover of my 350 and would like to know if anybody has tried it and whether or not it was successful.
Thanking You
Bob White.

[nevhunter]

I can't see why not Bob. The originals, especially for a sport bike or hard worked sidecar are a bit on the small side.The middle 50 's on had one at 2 o'clock from the drive side main, but I reckon some oil would be lost from that position. Nev

[Vincent.vanGinneke]

Bob White ? from Australia ? or am I mistaking you for someone else…..

[Bob White]

Vincent,
Have you had any experience with installing a breather into the tappet covers. My concerns are the effectiveness and whether it will interfere with the lubrication of the rockers. What do you think.
Thanking You
Bob White (Australia)

[Bob White]

Thanks Nev.

[Vincent.vanGinneke]

Hello Bob, I did once install a breather on the inlet side using the tappet adjuster hole that is on a late single.
Connected it up to a Yamaha reed valve that breathed into a sort of expansion can with a air filter on its exhaust.
grossly over engineered !
I suppose it would have worked but if it was benificial I doubt.
And I gave up over other issues with the bike, I sold it and the new owner took the system of.
So...in the end , I dont think it is of any use to fit a breather on the rockerboxes.

Many years ago John Bradshaw made special rockerbox caps with small gauze like filters, dont know what became of these as they where nicked at a rally...
Not from his bike but from the table where he had put them on show for others to asses, obviously someone took that to literally.

from the rockerbox a hose goes to the right hand side and under the seat frame tube to underneath a Yam reed valve, from there air goes to the bottom of a collector box that breathes out again via a air filter to the outside.
yes, completely over the top.....but what fun I had

[nevhunter]

It WILL work and you could make a special cap for the rocker so you alter nothing. The rocker is a positive oil feed and the worst thing that might happen if your engine has far too much blow-by, is a bit of oil may come out with the mist but that happens anyhow with the "normal" breathers. Try it with the cap off and a bit of foam over the hole to soak up any oil. I doubt it will be significant. Nev

[Bob White]

Thank you for the answers. I will give it a go and see what happens.

[andyhughesflattankarielpre25]

I dont known if its any help but a lot of quick HRD Vincents had them on the tappet covers,they were even made with a boss on to machine yourself,I had a ex sprinter one in the early 80s and that had them on both heads,it had the 2 thin pipes feeding into a catch bottle.I used to empty it about once a month.

[T Batnes]

How about fitting one of these, and a 1/4" BSP spigot and a hose. https://racingnorton.co.uk/epages/4c675 ... 0A2/707%22