Author Topic: Oil frothing in drip feed sight bowl  (Read 1357 times)

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Offline ian scott

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Oil frothing in drip feed sight bowl
« on: 11 Sep 2016 at 10:35 »
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?
« Last Edit: 11 Sep 2016 at 10:43 by ian scott »

Offline ian scott

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Re: Oil frothing in drip feed sight bowl
« Reply #1 on: 15 Sep 2016 at 08:21 »
My sight feed bowl has a breather hole. Is this correct?

Offline Ian

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Re: Oil frothing in drip feed sight bowl
« Reply #2 on: 16 Sep 2016 at 00:27 »
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.

Offline eddie

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Re: Oil frothing in drip feed sight bowl
« Reply #3 on: 17 Sep 2016 at 17:37 »
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.

Offline shuswapkev

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Re: Oil frothing in drip feed sight bowl
« Reply #4 on: 22 Sep 2016 at 09:13 »


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

Offline ian scott

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Re: Oil frothing in drip feed sight bowl
« Reply #5 on: 23 Sep 2016 at 00:42 »
Thanks. That's something to try. I'll cover the breather hole with tape and report back.

Offline Ian

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Re: Oil frothing in drip feed sight bowl
« Reply #6 on: 23 Sep 2016 at 03:09 »
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 !