Motorcycle Repair: 305 oil leak, gasket sealers, gasket surfaces

Question
I have a CL77 - 305 scrambler. When I assembled and started the motor it started pumping oil out the base gasket. I took it apart and put some gasket seal on the base gasket. When I started the bike after the repair it started pumping out oil from the alternator crank seal. The bike does have new rings and a fresh hone on the barrel. Why is the lower end seeming to pressurize and how can I fix it? Or is there something else wrong?

Answer
Cool! An actual vintage Honda question! :>)

You have to be careful about using gasket sealers/cement on Honda engines. They are usually put together with dry gaskets. You have to check and ensure that all the old gasket material is removed carefully and then that the gasket surfaces are all flat.

Seal failures are not uncommon when you are working on 40+ year old bikes. You can replace them, carefully, from the outside w/o splitting the cases. If the crankcase is getting excess pressure, due to unseated rings, you must ensure that the top engine cover vent passages are clear and that the breather plate was installed correctly. The two oval drain holes go to the bottom. If you put the plate on backwards, it will tend to pump oil out the breather tube. Be sure that the breather tube is not kinked or pinched.

I have full engine repair manual files included in my Restoration CD series for all 250-305 models. See details at www.vintagehonda.com

Bill Silver