Author Topic: oil flow  (Read 1183 times)

Online RDfella

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oil flow
« on: 23.08. 2017 16:56 »
Apologies if this has been covered before (new to this forum but did a search before posting). Here goes:
Just rebuilt a ’58 A10 and am wondering how much oil flow it should have. Return to the tank is just a dribble – far less than my B31 (I’m using straight 30 oil - my B31 is on R40). If I inject oil to the crank & refit pump oil return is a hefty flow for a few seconds before becoming just a dribble. I gave the engine a complete overhaul, including stripping / checking oil pump. Tried another pump (stripped and found in excellent condition) but no change. Oil flow to c’case with pump removed is good, so what am I missing?
I’ve been designing / building / rebuilding engines (including race bikes) for 50 yrs, so I’m stumped – normally people come to me when they’ve run out of ideas! 

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Online Greybeard

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Re: oil flow
« Reply #1 on: 23.08. 2017 17:13 »
Hi and welcome.  *good3*

Just covering the basics, that you probably already know. The engine has so called dry-sump lubrication: In other words the pump scavenges oil from the sump as soon as it arrives. Once any pool that has accumulated while the bike is stopped, (wet sumping is a real problem on some machines) is sucked out the return is a mixture of oil and air. So, once the engine is running properly you should be seeing a mixture of oil and bubbles coming from the return.
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Online JulianS

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Re: oil flow
« Reply #2 on: 23.08. 2017 17:47 »
Consider obstruction in oil lines, obstructed sump filter, pump to crankcase gasket of poor quality with oil holes smaller than those in the pump (yes they are being sold like that), missing spacer on front oil pump stud and worn and/or distorted oil pump.
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Online RDfella

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Re: oil flow
« Reply #3 on: 23.08. 2017 18:45 »
Thanks for that. Oil lines are OK (powerful return to tank when crank is 'primed' and good flow to oil pump hole when pump removed). Spacer is in place, pump not worn or apparently distorted. Will check gasket tomorrow.
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Offline Angus

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Re: oil flow
« Reply #4 on: 23.08. 2017 19:18 »
I think as Greybeard states this is usual behaviour. If the sump if primed/filled then you get a constant flow , but once the pump has drained it to a normal level then you get sort of spurts which is oil and air mix. Both my A's do this.

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Online RichardL

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Re: oil flow
« Reply #5 on: 23.08. 2017 19:23 »
RD,

There is a YouTube video online by some guy going by "bsathatgoesvroom" showing oil return back to the tank. Seems to be a very muddled amateur mechanic, but here is a link to one of his posts that will get you to the video.

https://www.a7a10.net/forum/index.php?topic=1251.msg8942#msg8942

Richard L.
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Online RichardL

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Re: oil flow
« Reply #6 on: 23.08. 2017 19:25 »
By the way, Welcome to the forum.  *welcome*. Whereabouts are you located?

Richard L.
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Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online RDfella

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Re: oil flow
« Reply #7 on: 23.08. 2017 20:13 »
Richard - thanks. I'm in Channel Islands (where the cost of living is twice that of UK - average cost of a 3 bed house here is £500k)
I've seen the video referred to. My return is a lot less than that. Spluttery of course, but just a dribble as opposed to an interrupted flow. Maybe I'm being over cautious as I'm not familiar with BSA A series. It's a bike I've had in the shed for 30 yrs. origimally bought as a frame for an engine I was developing, but I decided it was too good (read complete) to scrap and renovated it this year. Engine was clearly high mileage with several signs of incompetent 'repairs' over the years but I think I got them all.
As said, I'm a bit worried as the return (no wet sumping so return = flow) is way less than my other bikes, either current or previous - and they're rollerbearing not plain, so can manage with less oil. OK, so I never knew the flow on my japanese or Weslake, but one could guess it by consumption.
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Online RDfella

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Re: oil flow
« Reply #8 on: 23.08. 2017 20:16 »
Rep my recent reply - I see the site has an autotext. I entered J A P and it morphed into 'japanese'. Just to clarify any confusion.
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Online morris

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Re: oil flow
« Reply #9 on: 23.08. 2017 21:41 »
If it where any less than shown on the vid from (the very muddled  *smile*) bsathatgoesvroom I'd be worried...
After all, what comes out must first go in. As suggested by JulianS check if the oilways/gaskets/PRV are clear. The pump don't put much pressure so the smallest obstruction can hold back a lot of flow.
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Offline coater87

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Re: oil flow
« Reply #10 on: 23.08. 2017 22:13 »
 The only way I can think to confirm this is run a separate supply out of a clear container. That way you can monitor how much is actually going into the motor and how quickly its happening.

 Then depending on those results, go from there. *dunno*

 Oh yeah, welcome to the forum.

 Lee
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Online Greybeard

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Re: oil flow
« Reply #11 on: 23.08. 2017 22:53 »
There is a YouTube video online by some guy going by "bsathatgoesvroom"
That's you, right?
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Online Greybeard

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Re: oil flow
« Reply #12 on: 23.08. 2017 22:55 »
Rep my recent reply - I see the site has an autotext. I entered J A P and it morphed into 'japanese'. Just to clarify any confusion.

You are able to go back and edit your posts.
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Online orabanda

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Re: oil flow
« Reply #13 on: 23.08. 2017 23:51 »
Check the pick-up pipe in the sump is completely clear.

Remove oil pump. and blow compressed air into the pick-up pipe. Don't stay in front of the the timing crankcase (oil mounting surface); if all is well, plenty of air (and oil) will blow out (and over you).

Also check that the oil pump gasket is correctly fitted; not partially covering the ports for the pump.

Richard

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Offline duTch

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Re: oil flow
« Reply #14 on: 24.08. 2017 03:39 »

 Hiya RD- do you happen to have a magnetic anything somewhere near the scavenge pipe ? It's been known for this to hold the ball valve closed
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