Stumper - oil mist on head

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acadian

acadian

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Oil mist appeared suddenly in the areas pointed out in the image (primary side rocker cover, under tank, on downtubes). Have ruled out the rocker cover gasket and tacho drive.

Looking at head stud/pushrod tube area - completely dry at head to barrel joint, and the studs/holes in the head are dry as well. Nothing at cylinder base either, and the exhaust lockrings are dry. The only other thing I can think of is the crank breather outlet at just above primary at front of crank case. I'm stumped.

Stumper - oil mist on head
 
Besides the flood of normal head leak listing to come --- check fork seals and brake fluid sealing.
 
Check the rocker spindle cover plates are dry?
Also the rocker oil feed banjos?
 
Like they said. If it is on the down tube, it is Fork seal.
Nip up the seal retainers. Don't use Stilsons!
Ta.
 
Good tip re: rocker spindle caps or banjo, it's relegated to the primary side and seems to be misting upwards. Not fork oil, I'm running green synthetic stuff in there and this is definately engine oil.
 
I didn't get an image - and it needs a password on google drive ??

Always check the INLET tappet cover/gasket for oil leaks around there,
its been long pointed out the air flow is often backwards (to the direction of travel) in the vortex under the tank there.
I once had oil on a front mudguard, and it was indeed problems with the inlet gasket cover.
 
I can't see the pic either but you said the head studs are dry? I just experienced this after a few thousand miles post ring job. Oil from between the front fins migrating back and also exiting behind the RH exhaust rocker housing, running over and down into the spark plug recess. Never had an issue before since I use a smear of silicone around the pushrod tube openings. The head gasket joint was totally dry and it looks like I failed to retorque the head properly :oops: The centre 3/8" bolt was oily as were the 5/16" items. Surprisingly, a retorque stopped the leak, so far 300 miles.
 
Clean everything up, blow some baby powder on the suspected areas and run the motor. The oil leak will soon be revealed.
 
needing said:
Like they said. If it is on the down tube, it is Fork seal.
Nip up the seal retainers. Don't use Stilsons!
Ta.
Click to expand...

So the fork seal retainers should be finger tight?
 
My bad, Eric.
Don't use Stilsons 'directly on the retainer - sacrifice a jubilee clamp'.
Ta.
 
Traced the leak to the front rocker spindle cap. Thanks for the tips.

Now that I've got the belt set up I've discovered oil weeping past the crank seal (never leaked before), replaced with a new rubberized one, and still weeps once I get off the highway. I replaced the XS650 breather with the new version they're selling, but I think it's not doing the trick (especially with a new top end, and lots of pressure in the crankcase) Going to remount the old one, closer to the engine.

I suspect a lot of these new "mystery" leaks which have appeared have to do with the fresh top end and subsequent increase in engine pressure.

On a plus note, the Maney belt is set up like a treat!
 
Ugh, new rings and good valve seating implies rather less blow by pressure so re-think factoids on pressure weeps and note engine blow by does not enter gearbox to push oil into clutch. A good sealed engine stays sealed with factory breather systems, for a time anyway but stays sealed longer if engine vented below ambiant. Sillycon rocker gaskets and Hylomar + natural fiber thread is my attempt to get rusting fasteners after a season or so.
 
Hi acadian.
Re your "...I suspect a lot of these new "mystery" leaks which have appeared have to do with the fresh top end and subsequent increase in engine pressure..."
I'm with hobot on this one: if your top end overhaul included rings then less blowby gases would be able to pass the rings to pressurise the crankcases. I differ in my thinking to some others by aiming for neutral crankcase pressure by having one-way breathing in and out of my engine. Rationale: negative crankcase pressure encourages gases past the rings.
Ta.
 
needing said:
Hi acadian.
Re your "...I suspect a lot of these new "mystery" leaks which have appeared have to do with the fresh top end and subsequent increase in engine pressure..."
I'm with hobot on this one: if your top end overhaul included rings then less blowby gases would be able to pass the rings to pressurise the crankcases. I differ in my thinking to some others by aiming for neutral crankcase pressure by having one-way breathing in and out of my engine. Rationale: negative crankcase pressure encourages gases past the rings.
Ta.
Click to expand...

How do you aim for 'neutral' crankcase pressure ??
High pressure combustion gases aren't going to be discouraged much by the slight pressure in the crankcase either ??

New rings = sealing better could mean that the crankcase is pressurized MORE on the downstrokes though,
regardless of ring blowby. Depending on the breathing arrangements.
It was always considered that oil leaks were often from oil being forced out of the cases under pressure.

Not that this possibly has anything to do with the OP question here....
 
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