[dvnr] advise needed oil leak

[Daniel Sellers]

Bill
The screw circled in red is one of two machine screws that fasten the left
and right crankcase halves together independent of the larger bolts that
fasten the engine to the cradle. The oil is likely leaking from the same
location and some coming from the crankcase half joint and some getting out
of the same leak an weeping out the screw hole. Did the bolts mounting the
engine to the cradle work loose? Good luck sealing a leak externally after
oil has gotten between the existing seal between the case and sealant. You
might be able to reduce the leak by tightening the 1/4" machine screw and
mounting bolts.

These are my thoughts. I'm sure you will have some experts explain it
better.

Dan Sellers

On Tue, Mar 24, 2020 at 5:47 PM William F. Dudley Jr. via DVNR <
dvnr at casano.com> wrote:

> Hi,
>
> My 71 Commando is weeping oil out of the motor.
>
> There are two leaks.  One is the case joint between left and
> right halves, aft of the oil drain/oil screen.
>
> The other one is from the screw around which I have drawn
> a red circle in the attached photo.
>
> I don't want to disassemble the entire motorcycle for these
> stupid leaks.  I can goober up the case on the seam with some
> RTV and stop that leak, but the one at the screw is harder,
> since the screw is hidden behind the engine mounting plate.
> (I also have some more sophisticated means to seal that leak
> on the seam.  So I may not end up goobering it up with RTV.)
>
> I thought that if I drilled a hole in the engine mounting plate,
> right over that screw, then I could then sort out that leak
> one way or another.
>
> Questions:
>
> 1. what does that screw do?  Does it just plug an oil way after
> the factory drilled the oil way during manufacturing?
>
> 2. Does anyone have a Commando case not mounted in a motorcycle
> from which they could measure 'X' and 'Y' as shown on my drawing?
> That will help me locate where to drill.
>
> I plan on putting a stainless plate between the engine mounting
> plate and the crankcase when I drill, so that I don't overshoot
> and make a mess of the case.
>
> Thanks,
> --
> Bill Dudley
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