Oil consumption

[BruceM]

Since I switched to 90wt oiling of the rockers and caps, I never add oil to the valves, in fact I have to remove excess oil on occasion. 

[lowspeedlife]

For anyone who is interested, the owner of the OSL site used to be a member of the old LEF. he was banned from there for making eronious claims about his engines (100,000 hour run times or more even though he had only sold them for a few years) he also had several user accounts on the forum & would have discussions with himself about how great his engines are. you may wish to take anything he says with a grain of salt.

SR

[dubbleUJay]

Thanks lowspeedlife, didn't know that!
I must say that some of the modifications I've seen on the "original" site was quite interesting though and the explanations givin' for some wasn't all to far fetched, but I wont take anything for granted now!

[Capt Fred]

Bit off topic, but getting a lot of oil leaking around the tappet collets,  kinda don't want to mess with them cuz got the little buggers spinnin' like four whirling dirvishes - but sick of the mess.  Think I remember it was Xyzer (if not appologies) machined some heavy duty hold-downs.  Would replacing the stamped steel crappy ones withbetter hold-downs do the trick or do I need to pull the collets and install new gaskets - or maybe machine o-ring grooves?

Any and all ideas greatly appreciated.

Cheers Fred

[dubbleUJay]

Capt Fred, maybe your vacuum breather ain't working as it should? I also have no gaskets on mine. (Dursley)

[potter]

Yes i would definitely check the vacuum, mine are really sloppy but look so dry that i on occasion give them a squirt of oil that soon gets sucked away.
 
  Potter

[Capt Fred]

That's kinda what I thought, I've taken the breather apart and cleaned the component - but has not had any effect, pressure is normal on the gauge but lots of weeping oil on the deck.

That being said, something is amiss, will have to dig a bit deeper and find the problem.  Thanks, I really want to find the problem, not treat the symptoms.

Cheers, Fred

[dubbleUJay]

Maybe its "normal" then because of sloppy tolerances on the 2 cylinder 'roids?
A  smallish diameter pipe taken from between your air-filter and head intake to the crankcase should give it some vacuum like on a petrol engine to boost the brakes (not at the same -pressures though), but like you said, don't treat the symptoms!
If someone decides to try it, for obvious reasons, PLEASE, above the oil level, preferably at the existing breather somewhere! 

That said, even the Dursley Lister's had a vacuum in the crank case for oil slobber, so it was/is a problem, how much oil will come out without it I don't know, mine have no oil leaks anywhere.

dubbleUJay

[Ronmar]

On a twin, if you are still using the thin metal reed valve plate, that could actually be trapping pressure in the engine placed there by blowby gasses.  This little bit of blowby is leaking out thru every small hole and pushing oil with it.  Because of all the holes, it never builds enough pressure to lift that breather reed valve and vent the gasses that way.  Ideally, the twins would have a divider plate between the halv's and an individual flapper type breather on each crankcase half.  Since the twins don't have this internal divider between the crankcase halvs, they really don't get any vacume action from piston travel like the singles do with the oneway crankcase breather. 
I would ditch the top half of that stock breather and make a flat plate with a hose fitting in it, run up to the intake manifold.  This will put a little negative pressure on the case, and hopefully cut down on the weeping oil.  Failing that, again remove the top plate on that stock breather and just put on a big filter, so the case is as near to atmospheric pressure as possible...

I replaced the upper half of my crankcase exhaust vent with a plate and a 1' NPT fitting welded on.  this was real easy to do...  This allows me to screw on a brass check valve with the spring removed(gravity holds it closed).  The top of the checkvalve has a threaded output so I can tassily add a hose/pipe to vent the gasses outside, or into the intake, or into the exhaust.  I havn't vented it anywhere yet, it just has a sock tied to it to collect the oil mist as I wanted to see just how much oil gets carried out that way...   

[Capt Fred]

I like that, think I'll go with the modified checkvalve and vent outside. 

Thanks, Fred

[BruceM]

On my 6/1 I also use Ron's setup; modified brass check valve,  mine's plumbed  through an outside wall. I think I stole the idea from Ron, it was another of his many good ones.

Interesting to learn about the weak vacuum in the twins.

[BruceM]

Jens, is your added vacuum breather a crankcase connection to the intake manifold? 

[BruceM]

Nice work, Jens.  Do you have a photo of your successful venturi?

[BruceM]

The thickest portion of the venturi is only about 1/4"

Huh?  From the other part it sounds like it fills the entire intake, but surely it doesn't taper to 1/4" at the waist of the venturi.

[rcavictim]

I must be losing it.  I could'a swore I posted a public service informational post about venturi here when I last logged in.