Case separation

[BruceBishop66]

Pulling my 1980 cb750k engine apart to check for warn bearings, but I'm having a heck of a time getting the case apart. Yes, I have all the bolts out. The oil pump is still on but all of the bolts that hold it in place have been removed. It (the oil pump) just doesn't want to budge.  
If your advice is "You have to take the oil pump off first", then don't bother unless you can tell me how.  
Really appreciate any help.
Thanks

[sgtslag]

Have you downloaded the FSM (Factory Service Manual)?  Directions should be within its pages.  Other than that, if it is completely released (all the necessary bolts removed), you may need to apply a rubber hammer to loosen it.  After 30 years, it may be a bit stuck.  Sorry I can't be of further help.  Good luck.  Cheers!

[BruceBishop66]

Ha! Yea, 30 years of STUCK. Time for a thorough thrashing with a mallet.
At this point, any advice that starts with "don't do this" might be helpful.

[GTO6T6]

+1 to the rubber mallet.

Also recheck twice that you have all the bolts removed from the case.  It's easy to miss one, especially the one in the front of the oil pan area.  Once you've got the oil pump out, and all the bolts removed from the case, I:

1. Flip the engine over (top case towards floor) & put it on something soft (like a junk blanket)
2. Put one of the long frame mounting bolts through the bottom case half with a heavy duty wire loop in the middle.
3. Put a 2x4 across two saw horses and hang a ratchet strap off it connected to the wire loop.
4. Raise the back of the case a little off the floor (blanket bunched up to provide a soft surface)
5. Grab a small section of 2x4 and hit that with a BFH around the case (don't hit the case directly with the BFH).

The weight of the crank & transmission will pull down on the top case, and the smacks transmitted through the board will loosen the case sealer.  

[LukeM]

There is a bit of sealer between the two case halves from the factory, and putting it back together says to put some more inbetween.  With my motor, the oil pump was the issue.  A couple of extra bolts we overlooked. Also, I second the "missing bolt" theory.  We also had to remove the alternator, even though the FSM said we didn't have to.

Hammer is recommended over a large prybar, since there's no real good place to pry on the covers.

If all else fails, use a little heat on the seam.  Just don't overdo it.  To correct another posting, metal expands when it gets hot, and shrinks when it gets cold.  Different metals expand/contract at different rates, depending on their composition.

Luke M

[palbradley]

I followed along with the post trail as I too was separating my crank case. I hung my engine as described and it worked. However, it wouldn't come completely apart. 95% apart except one area near the generator side of the case. I can put my hands inside most of the crank case, but only my fingers around the side near the generator. I have turned the drive shaft thinking some of the gears might be suck but that didn't free the crank case either. Any idea of what could be "catching" and preventing the crank case from separating completely? My bike is a 79 cb570K model.

[GTO6T6]

Did you remove the rotor too?  That also has to come off before you split the cases if I remember right, though it's best to check the service manual.