Triumphrat

davetile

I just resurected my 1960 bonne. It was dumping tons of engine oil between the primary chaincase backplat and the engine block. I took it apart and the main seal on the front sprocket fell out when I pulled the sprocket off. Put a new seal and entire new clutch while I was at it, also put a gasket behind the chaincase backplate. Ran the bike and noticed about a tablespoon of engine oil drips right after I shut down the warmed up bike. It seems to be coming out of the crankcase breather hose. After about a tablespoon drips from under the bike it stops dripping, indicating that it leaks only when running.I also have noticed that the oil pressure indicator gets less visible as the bike gets hotter. I'm not sure if this is normal. I put about 30 miles on the bike and it ran fine. Any one know what's happening? Is it blow by? A weak oil pump causing oil to pool in the crankcase?

Red1959

My pre unit oil pressure gage also tends to peter out as the temperature rises. This is normal, but should indicate some pressure.Watch it returning into the tank and if your rocker box shows some seepage it's fine! As far as leaking oil, good luck stopping it. I had so many leaks, I've had a lot on this particular bike. The rubber inside the oil pressur gage gave out and made a mess. I've been told that a pressure relieve valve w/o the protruding indicator can be used.
If you think the oil pump is leaving more oil in the case than it pumps out, I would think that eventually all of the oil would fill up the crank, and that could be a cracked return pipe . If it is circulaing, it's most likely okay. My bike leaks a tablespoon or so after every ride, but I believe it is a result of a lot of minor leaks combined . Ive haven't sucessfully stoped the sump pump access so a little comes from there, some comes from the timing side by the generator, some from the vertical split cases and blows around collecting under the motor. A small crack in the primary case dosen't help either.
Even after all of these minor leaks, I can,t tell if the breather leaks at all! It proboaly puts a mist out and collects under over sideways down! Well , that's my experience so far . Iv'e had better oil tight bikes with the unit construction.

__________________
Martin Cvitkovich: www.thesplitbook.com

davetile

Thanks for the reply. It seems like 90% of the oil is spraying out of the crankcase vent pipe. I think I'm going to check the compression, people are telling me there might be some blow by caused by a sticking ring or maybe varnished cylinder walls. The bike runs great though.

PfM

My 1961 always blew oil out the breather, even after the top end rebuild. It has a Morgo pump in it and returns oil to the tank so I am not worried about that. I did suspect the rotary breather valve was kaput, but it did seem to pulse the way it should.
I ended up running the breather pipe back up to the oil tank. Still not sure if this is the right thing to do - concerned about pushing oil up that far. Haven't really done enough miles to call it a win or not, but it certainly cut down the oil stains on the concrete.

Cheers

davetile

my old man suggested the same thing; to connect the vent pipe to the oil tank.

Red1959

Let me know how you go about putting the hose on the breather pipe. Unless things are different on my bike, a hose should have been added durring assembly.

__________________
Martin Cvitkovich: www.thesplitbook.com

bushybester

Davetile.

I welded in a 3/8 copper pipe at the back of the oil tank well above the oil line and connected the breather to that, thinking that one could see when the oil returns to the tank. Same problem too few miles.

I think it should work well, no oil on my floor.

BB

DAGAD

OIL PUMP.............................
Roy.

Ahobie17

I would be a little concerned about venting to the oil tank (oil tank is sealed isn't it?) as wouldn't that increase pressure to the tank and crankcase??? might cause some other problems as I believe the engine needs to get rid of the positive internal pressure. Seems like leaks would become an issue.
Just my thoughts on venting to the oil tank, be it right of wrong.

Trumpet1

Years ago I welded in a pipe on my 61 bonne to discharge breather oil back into the tank. It worked great. I didn't think about the fact that it might pressurize the tank. I probably should add a vent to equalize the pressure ,but it works and I have ridden many miles that way. No more oil stains under the bike.