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Somebody's siphoning my oil! #272584
08/30/09 7:49 pm
08/30/09 7:49 pm
Joined: Jul 2009
Posts: 65
MO, USA
R
rg500g Offline OP
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rg500g  Offline OP
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Joined: Jul 2009
Posts: 65
MO, USA
I ride a '71 Lightning can't figure out where it's going. I check the non return valve in the sump and it lifts OK, cleaned it with carb cleaner and dbl checked it anyway. I use 50wt sgl vis oil and don't pull away until engine is warmed up (fins too hot to touch for more than secs or so, or ~ 3-5 min idle). No oil smoke from exhausts, plug cermaics and electrodes dry (Ch N4C), and still I go from mid stick to bottom mark in a couple of tanks (US Tank). No puddles on the floor save a bit from the chain oiler and trans, 0 engine oil on floor. I understand that crankcase vent can contribute to this, and every now and then I see a small spot by rear fender where the vent exits, but seriously, 100+ ml worth?

I check oil by starting the bike and getting it warmed up, then putting it on center stand and checking oil level quite soon after turning it off, like within 2 min.

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Re: Somebody's siphoning my oil! [Re: rg500g] #272587
08/30/09 8:02 pm
08/30/09 8:02 pm
Joined: Dec 2002
Posts: 406
Chelmsford MA
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MarcB Offline
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MarcB  Offline
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Chelmsford MA
If it was leaking out, either when standing our out the breather, you'd know. You can't lose that much oil without making a huge mess.

Assuming it's not down in the bottom end, then it's burning. There's nowhere else for it to go.

Stick your finger in the exhaust and feel around. Any stickiness? If so, that's your oil.

My newly rebuilt A65 is doing the same thing. I never noticed any smoke but a couple guys I was riding with said they smelled it.

Re: Somebody's siphoning my oil! [Re: MarcB] #272613
08/30/09 10:45 pm
08/30/09 10:45 pm
Joined: Mar 2005
Posts: 731
Asheville, North Carolina
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ca7a Offline
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Asheville, North Carolina
A clue is that "small spot"; the oil is most likely venting. Age of engine?

David

Re: Somebody's siphoning my oil! [Re: ca7a] #272616
08/30/09 11:05 pm
08/30/09 11:05 pm
Joined: Jul 2009
Posts: 65
MO, USA
R
rg500g Offline OP
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rg500g  Offline OP
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MO, USA
poked a finger in the mufflers and came out with a fairly dry, fluffy carbon coating on the finger. Neither side was different from the other.

I have every reason to believe that the engine is unmolested and has never had any work done on the top end. The odo reads 7K+ miles but that means nothing. Cranking compression is good, topping out around 140 PSI and both cylinders track w/in a couple of PSI of each other.

The most likely culprit I see would be crankcase venting. If one were to try to minimize this loss, how would you go about it? Usually, one puts a big can inline in the vent outlet where the oil mist condenses on some internal baffles and collects in the bottom of the can. You empty it periodically, but the loss is still there - you just get to see it. Also, no room on the bike for that. Do I need to address the crankcase venting to 'fix' something?

Re: Somebody's siphoning my oil! [Re: rg500g] #272639
08/31/09 3:21 am
08/31/09 3:21 am
Joined: Aug 2001
Posts: 3,881
Cape Carteret, NC
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Mr Mike Offline
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Joined: Aug 2001
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Cape Carteret, NC
rg,
Ya know there is always some coming out the breather. You see a drop when you park it but it is coming out all the time the motor's running...but should be no where near the amount your are losing. Idle it for five minutes and mwasure the oil level. Drive it for an hour and recheck in exactly the same manner. If it runs good, your not fouling plugs, run it..... oil is not too expensive.... but it is a puzzle.

Mr Mike

Re: Somebody's siphoning my oil! [Re: Mr Mike] #272640
08/31/09 4:27 am
08/31/09 4:27 am
Joined: Oct 2007
Posts: 1,524
Auckland NZ
Ignoramus Offline
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Ignoramus  Offline
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Auckland NZ
Rg....have you pulled the level or drain screw on the primary cover? Have a big tin handy just in case .....could be shot crank seal ....just a thought.


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: Somebody's siphoning my oil! [Re: Ignoramus] #272681
08/31/09 2:31 pm
08/31/09 2:31 pm
Joined: Aug 2001
Posts: 3,881
Cape Carteret, NC
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Mr Mike Offline
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Mr Mike  Offline
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Cape Carteret, NC
Ig,
Interesting. Yesterday I went out to start my B50 which failed to start about a month or two ago and now has not been started in about 3 months. As you may know the B50 primary shares oil with the engine. Anyway when I changed a fouled plug, I checked for spark and removed the inspection cover to check timing. Oil poured out over the grass before i could get a pan under it. In the three months that the bike was idle, it wetsumped and drained over into the primary because the bike leans that way on the stand. You gotta start these bikes every month or so or drain out the oil from the sump due to wet sumping. My A65 takes about 6 months to lose a pint (no big deal) and it is an easier starter than the B50 so it gets ridden more often and never wetsumps to the point that all the oil is in the sump.
This doesn't help RG, but i thought it was an interesting followup to your comment.
Mr Mike

Re: Somebody's siphoning my oil! [Re: Mr Mike] #272796
09/01/09 6:30 am
09/01/09 6:30 am
Joined: Oct 2008
Posts: 4,934
Gnashville
DavidP Offline

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DavidP  Offline

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Gnashville
Originally Posted By: Mr Mike
In the three months that the bike was idle, it wetsumped and drained over into the primary because the bike leans that way on the stand. You gotta start these bikes every month or so or drain out the oil from the sump due to wet sumping.
Mr Mike


My A65 needs to be run every two or three days or the primary fills up (about a pint.) Mine has been modified to breathe as the later Triumphs, with two small holes drilled at the level of the bottom run of the chain.
It doesn't smoke, but it does use a bit of oil.
I'll put up with it until this winter when I clean the sludge trap, and inspect the bottom end.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
Re: Somebody's siphoning my oil! [Re: rg500g] #272836
09/01/09 2:33 pm
09/01/09 2:33 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

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Seattle
Originally Posted By: rg500g
I ride a '71 Lightning can't figure out where it's going. I check the non return valve in the sump and it lifts OK,


FYI, that ball valve has nothing to do with preventing wetsumping. It merely keeps the return and, hence, the oil feed to the valves primed.

And yes, you're probably burning the oil. Hard to see oil burning when it only happens on the throttle. Look at your piston crowns @ TDC through the spark plug hole with a flashlight or an odoscope. You should see oil on the crowns.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: Somebody's siphoning my oil! [Re: Alex] #272868
09/01/09 8:16 pm
09/01/09 8:16 pm
Joined: Jul 2009
Posts: 65
MO, USA
R
rg500g Offline OP
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rg500g  Offline OP
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MO, USA
I did examine the crowns from the plug holes, and both crowns are dry. I habitually check out crowns due to owning a roadrace two stroke, and it's a habit I carry over to the BSA. I've noted detonation at moderate acceleration under load, quarter to half+ throttle, and check plugs for specs, and check crown while I'm at it.

Originally Posted By: Alex
Originally Posted By: rg500g
I ride a '71 Lightning can't figure out where it's going. I check the non return valve in the sump and it lifts OK,


FYI, that ball valve has nothing to do with preventing wetsumping. It merely keeps the return and, hence, the oil feed to the valves primed.

And yes, you're probably burning the oil. Hard to see oil burning when it only happens on the throttle. Look at your piston crowns @ TDC through the spark plug hole with a flashlight or an odoscope. You should see oil on the crowns.

Re: Somebody's siphoning my oil! [Re: rg500g] #272893
09/01/09 11:50 pm
09/01/09 11:50 pm
Joined: Oct 2007
Posts: 1,524
Auckland NZ
Ignoramus Offline
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Ignoramus  Offline
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Posts: 1,524
Auckland NZ
Rg
sounds like youve done pretty much everything else .....have you drained the primary case to see if its full of engine oil due to a dud crank seal?

It might be burning a bit but from what you say i recon if it was burning that much it would be noticable ....specialy at night in following cars headlights


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: Somebody's siphoning my oil! [Re: rg500g] #273041
09/03/09 2:02 am
09/03/09 2:02 am
Joined: Apr 2002
Posts: 716
Out There!
N
Nick Offline
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Nick  Offline
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Out There!
Slightly off topic, but I wonder about the wisdom of warming up air-cooled engines. People who know more about this topic than me have advised against it.


When people who should have known better cautioned me about the dangers of motorcycle racing, I always told them that a fear of death is nothing more than a fear of life in disguise.

Moderated by  Allan Gill, Jon W. Whitley 


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