Removing Cylinder Head...Seperating the Crank Cases

[crewinitup34]

I just bought a 67 cb77 305 parts bike...I am completely new to motorcycles and wanted a project.
I apologize in advance for not knowing all the terms.
I have two engines and I want to build one reliable engine from the best parts.
Therefore, I hope to tear everything down as much as possible so I can compare the parts from each engine.

One engine - that looks to have a greater quantity of good condition internal parts-came with the cylinder head off and all the head components look pretty good and I am at a standstill because I need to separate the upper crank case from the lower. The Tusk crank case splitter looks really good in the youtube videos but those featured crank cases that were assembled in the left/right manner.
What is the typical process if a rubber mallet just isn't getting it done.

My most pressing dilema is with the second engine. I was able to get the two casing components that make up the cylinder head to lift off the upper crankcase slightly and I cut the timing chain. Now it lifts off the case a few inches and the crank turns about 180 degrees before the head seems stuck and will not lift any further. I would really appreciate any recommendations. Also, the valve covers are all jammed on pretty good and came with fairly rounded corners on the outside nut surface.




Please post questions If I have not been clear.

[G-Man]

Hi, and welcome to the forum.

For your first problem, you need to check and, double check that you have removed all of the nuts holding the cases together. Unlike a vertically-split crankcase there is nothing 'holding' these together other than the fasteners. There are nuts on top and underneath the cases so check very thoroughly,

On the second engine, the pistons are rusted in the bores so you need to work very carefully with heat and penetrating oil to get them free. There are several posts here on how people have overcome this problem which is very common with these bikes.

Please send some pictures. It is much easier to diagnose problems when we can see what you can see.

Good luck!

G

[crewinitup34]

Hey G-Man, Thanks for the reassurance that the case would come apart once all the fasteners were removed.

I have been extremely reluctant to intentionally destroy parts up to this point. But the screws on the cover for the starter motor were just not going anywhere and I decided that that cover was ready for an encounter with the aviation shears. The shears were up to the task. Once I was able to get those bolts out from under the starter cover it came apart quite easily and the entire engine is bagged and ready for cleaning.

Since this is my first tear-down and build up I ordered the Bill Silver Honda 250-305cc Engine Repair Guide for $30 and I'm not going to do anything with the good engine until I have taken a good look at what Mr. Silver recommends.

On the other engine I was able to remove the cylinder head by sticking a thin piece of plastic (a very thin ski wax scraper) between the cylinder head and the cylinder housing. This allowed me to dig out all the orange crud and sunflower seed shells that were sitting on top of the piston in the cylinder. I have let it soak overnight with penetrating oil and used heat and have had no luck...I will keep trying this until the Bill Silver book arrives and then the focus will shift to the primary engine.

Anyway
What a feeling when that crank case seperated.

Thanks again for the advice G-Man. (I will have my camera up and running soon as well)