Overfull Primary

Hungry J0e · Apr 25, 2011

Got my bike's plumbing back together and ready to go back on the road. Checking all the fluids after the winter layup, when I removed the primary level plug about 3/4 quart came out.

After getting the primary drained and filled to the proper level, took her out on the road. No more leaks from the plumbing lines which is good. Clutch action is fine as well with a good neutral and no dragging.

I can only guess that after the bike wetsumps up to the crank in the winter, the oil is leaking over to the primary from there. Other than not wetsumping, any ideas out there on how to cut down or eliminate the loss of oil to the primary?

(at least I know where a substantial portion of my oil loss is going)

Cheers,

- HJ

lrutt · Apr 25, 2011

do you drain the sump when it wetsumpts? I really should not be leaking past the seal when just sitting. If so, the seal needs replacing. But when running the pressure can force some past if the sump is full.

Hobot · Apr 25, 2011

Engine oil can also weep through the 3 bolts holding the inner case on but more likely the crank seal. I'd just ride it and see if it ain't much an issue regularly run but if it still is a new seal &/or a smear of sealant. As long as enough oil in tank to feed engine a few seconds on starting no need to drain sump, just don't blip up high till pumped down of may weep oil in many places for some minutes. Traditionalists tend to leave crank with pistons near TDC to increase-slow the path oil must leak up and out. Don't forget the other oil source via the tranny main shaft sleeve bushes.

BillT · Apr 25, 2011

Oil leaking from the crankcase to the primary seems fairly common for bikes that sit over the winter. I've found that wet-sumping is not an issue when ridden regularly.

I suppose the thing to do is to drain the oil tank when being put up over the winter. You could drain the oil into an empty gallon container, and re-fill in the spring. Just make sure you've tagged the bike to remind yourself the tank is empty before initial start-up.

I'm also one of those who uses ATF in the primary - it's an easy way to tell if you've got oil weeping past the crank seal, as the motor oil turns the ATF from red to brown.

Hobot · Apr 25, 2011

Ugh Bill when ya use ATF in primary you lose some to the quaint British accent and if ATF also in tranny ya may acquire a southern drawl like me no one associates with proper Nortons : ) shush up or lose respect.
I only fill primary so chain bounce just touches resting lube level.
Helps a bit to store on center stand instead of leaned L on side stand. Iso's and tires prefer that I hear too.

pete.v · Apr 25, 2011

hobot said:
Engine oil can also weep through the 3 bolts holding the inner case on.

I've noticed this only after installing a belt drive and is much more common than one would expect. If oil is at or just over the normal level in the crank (6 to 8 oz.) it may reach the lower bolt. Very Little wet sumping is needed to leak into the primary and very little pressure required to push oil past the threads. Not to disspell crank pressure claims,the need for reed valve or to reseal the top on that old can of worms but notice how the bolt hole is a good 1" to 2" below the seal line.

DogT · Apr 25, 2011

The leaking through the crank bolts was a reason hobot used red locktite on them with studs. I did it too, we'll see, all the oil's been in the sump all winter, haven't checked the primary yet, but will before heading out, as well as draining the sump and putting back in the tank.

Dave
69S

Flo · Apr 25, 2011

Or you can smear your favourite gasket goo around the threads.

ashman · Apr 25, 2011

Hi All

Wouldn't it be wise to do a complete oil change after a winter lay up, as I don't have this problem here as we ride all year round, our winter is only mild and is the best time for our British bikes, I put some gasket goo on the treads of my primary bolts and haven't had any problems with oil leaking into the primary but I run a belt with the back part of the inter primary case cut open and some air holes in the front of the inter primary case for air flow, but from the side it looks like a nomal primary case.

Ashley

davamb · Apr 25, 2011

Just gone through exactly the same issue. I used Copper crush washers on the three bolts which has improved matters substantially. There was a little bit of dribble on the (new) main seal, but this has stopped since draining the sump and tranny case level now seems to be constant.

Hungry J0e · Apr 25, 2011

Thanks for the advice all...

Just to be clear, I can access said bolts once the primary cover is off?

Will keep an eye on the issue. If I have a recurrence I'll goop them next time I'm inside the primary.

Cheers,

- HJ

DogT · Apr 25, 2011

You'll at least have to take of the chain, which will include the clutch parts, stator and rotor, so it's not just the outer cover.

Dave
69S

Overfull Primary

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