Oil frothing in drip feed sight bowl

[ian scott]

Hi, I'm getting oil frothing back up into the sight bowl on my 2&3/4. It's been doing this quite a while. The one way valve on the oil feed line works very well off the bike when I suck and blow with my mouth. I have stoned both of the mating surfaces of the valve - the disc and its mating surface.

Today I checked the crankcase breather valve to the timing chest. I was thinking that if the breather didn't work the excessive crankcase pressure might overcome the one way valve on the feed line. However all seems fine. I'm using one of the LDMCC springs and a 1/4" ball on the breather.

The motor is getting enough oil or it would have seized years ago but it is disconcerting to see frothy oil filling the sight bowl.

Any ideas?

[ian scott]

My sight feed bowl has a breather hole. Is this correct?

[Ian]

On my OC I have always had the situation where the oil splashes round a fair bit until the motor is warm. The one way valve seems to work fine - but I think it may get a little sluggish when its cold. However that one joins directly to the front cylinder. The TS has never had that issue.

I will have a look later but I do not recall any breather holes in any of the sight feeds.

[eddie]

Check out the sight feed glass - make sure there are no leaks at the ends, or cracks in the glass. If the breather valves are working correctly, the engine will create a partial vacuum in the oil line, and draw air into the system.

  Regards,
               Eddie.

[kev]

  neither of my sight feed bowls has a hole...
     try some epoxy over and see if any difference

[ian scott]

Thanks. That's something to try. I'll cover the breather hole with tape and report back.

[Ian]

Mine does not have a breather either

I was remembering ages ago when a leather washer in the pump failed - the one-way valve created enough vacuum to drag some oil through !