You may want to check your chain adjustment, and make sure it has enough slack in it and no kinks. As your suspension goes up and down the chain gets tighter as it travels. If you do not have enough slack you will put a load on the counter shaft, bearing and seal. This will cause a intermittent leak. You should also inspect the sleave that goes behind the countershaft sprocket to make sure it is not pitted or scored. After time and miles the seal will wear though the chrome and allow oil to leak.

As for a hole from the transmission to the crank case...I don't think so...all the preasure from the piston would blow into the transmission.

As for using a sealer of any kind...also I don't think so. In a car with a seperate clutch/transmission maybe (not what I would do) but never for a engine with a wet clutch and transmission.

Ben
87 300tecate-4