Oil leak - Countershaft

[machten]

I'm sure this is a dumb question, but I'm still very much learning about singles. I have a 68 250 MKIIID that is leaking oil past the countershaft/sprocket. It isn't pouring out or anything, but more than enough to be annoying. Is the seal internal and am i looking at a split to fix it, or is there another way?

Kev

[Jon Pegler]

It involves splitting the cases, I'm afraid.
The seal is part of the bearing supporting the shaft itself. Bearing no. 6204ZZC3.

[machten]

Thanks Jon,

That's what i thought was going to be the outcome, but wasn't sure. As it is a new bike to me and perfectly (in fact, wonderfully!) rideable, i'll live with it for a while and see if there are any other obvious issues I should deal with at the same time before biting the bullet. Thanks for your help.

Kev

[DewCatTea-Bob]

____ Welcome as our latest new listed-member Kev !


" I have a 68 250 MKIIID that is leaking oil past the countershaft/sprocket. "

____ The shield on those counter-shaft bearings rarely go bad before the bearing itself does...
And motor-oil (other than a slight oil-mist) should never leak out through that space, unless your oil-level is too high ! ...
What most always happens when DUKE-owners run-into this somewhat common occurrence, is that the petcocks have been left turned-open too long and fuel leaks down-into the crankcase, thus raising the crankcase's oil-level too high & up past the height of the counter-shaft bearing's outer-race.
__ You should check that your oil-level is not past where it should be, and if your oil is smelling of fuel, dump it and replace with 3-quarts of fresh motor-oil. _ Use it for about a hundred miles so as to flush-out the diluted-oil which you couldn't get entirely dumped before, and then replace your motor-oil again.


DUKE-Cheers,
-Bob

[Jordan]

What most always happens when DUKE-owners run-into this somewhat common occurrence, is that the petcocks have been left turned-open too long and fuel leaks down-into the crankcase
-Bob

Yes, I've seen that happen. Carburettors with remote float bowls especially, as the float needle doesn't seem to be able to seal very well.

[Eldert]

i would replace that bearing with a 2RS type bearing ( rubber shielding ) instead of the metal shielded ZZ bearing

you can either whip out a shield on the inside of the gearbox if your concerned about lubrication or leave it in
this will work to

Eldert

[machten]

What most always happens when DUKE-owners run-into this somewhat common occurrence, is that the petcocks have been left turned-open too long and fuel leaks down-into the crankcase, thus raising the crankcase's oil-level too high & up past the height of the counter-shaft bearing's outer-race.

That has definitely happend. One of the petcocks will not shut off properly and the float needle is not sealing properly either (I've tried a new needle, but the seat is the problem. It's not a removable one, so I'll need to tidy that up to get a good seal somehow. This is running a VHB rather and SSI. I've ordered some new percock seals. Once I've dealt with that I'll dumpt the oil as suggested and see what happens. Thanks Bob - hopefully some reason for optimism and sure worth a try!!!

i would replace that bearing with a 2RS type bearing ( rubber shielding ) instead of the metal shielded ZZ bearing

you can either whip out a shield on the inside of the gearbox if your concerned about lubrication or leave it in
this will work to

Thanks Eldert, I'll store that info away if it comes to a split.

Regards,

Kev

[DewCatTea-Bob]

" One of the petcocks will not shut off properly and the float needle is not sealing properly either "

____ Ya can't even trust new carbs with perfectly made float-valves, ya need to keep good-working petcocks shut-off whenever your Duke is not running -(parked) for more than 10-minutes. _ It's also a good idea to turn-off petcocks about a minute before you intend to park your Duke (so as to run-out most of the fuel from the float-bowl).


" Once I've dealt with that I'll dumpt the oil as suggested and see what happens. "

____ It should be of interest to measure the volume of the dumped fuel-contaminated motor-oil after you get it all out, so as to get an idea of how bad the fuel/oil ratio came to be.
Luckily, your camshaft probably has not become too scored-up since the valve-spring pressure is considerably less within a DESMO-head.
__ When you dump your oil, try to get most all of it out, by tilting your Duke side to side... First dump what will come-out while on the center-stand, then tilt to left-side and after the flow slows to a drip then tilt to right-side for a few minutes, then back to center-stand,, and then soon after, tilt to left-side again, (it may pay to go through that tilting-process more than once, depending on how warm your motor is at the time).
__ If you get-out ALL of the oil from the entire motor/engine, the wide-case crankcase oil-sump should then be up-to accepting a full 3-liters of fresh motor-oil.


Hopeful-Cheers,
-Bob