Topic: Splitting the case... CB650.

[Tom Witt]

I'm currently parting out a 1980 CB650 Custom.
See that thread here:
http://forums.sohc4.net/index.php?topic=103223.0

When I acquired this bike, it was already partially disassembled. The previous owner has removed the head to repair a seeping head gasket, and ended up stripping out a head bolt. That's where I came in. I've sold off several components and now I'm working on breaking down the lower end. It would appear that all of the required bolts have been removed to split the case, however... I can only get it to crack open about 1/4-inch, maybe 1/2-inch on one corner. Something near the front left corner appears to be hanging it up.

Most of the accessible items have been removed (clutch, strainer, oil pump, etc) and I really don't know what else could be holding it up. I've consulted my service manual multiple times. I just don't see it.

I DO still have the rotor attached (which I've not figured out how to remove that yet either), but that doesn't seem like it's holding anything up.

Looking for some tips/suggestions. I'm obviously a rookie at this.

[thrutheframe]

  Hey Tom, first let me say sorry I didnt get with you about that grab bar, money got tight here and you slipped off of my radar. 
  The rotor is actually really easy to remove despite looking really hard.  If you still have the rear axle, thread that into the rotor the use a hammer or hatchet to tap on the head of the axle bolt to remove the rotor.  I used a hatchet because it was easier to slide along the bolt and me solid contact with the head of the bolt.
  Sorry I can't be more helpful on the rest, I've never cracked the cases on one of these bikes either.  Hopefully that will get you past your "sticking point",

[Tom Witt]

Hey Tom, first let me say sorry I didnt get with you about that grab bar, money got tight here and you slipped off of my radar.

No worries man. As long as you don't leave me waiting on the side of the road, I'm good. Parts deals occasionally fizzle. It's not a big deal. These parts usually sell themselves.

The rotor is actually really easy to remove despite looking really hard.  If you still have the rear axle, thread that into the rotor the use a hammer or hatchet to tap on the head of the axle bolt to remove the rotor.  I used a hatchet because it was easier to slide along the bolt and me solid contact with the head of the bolt.
  Sorry I can't be more helpful on the rest, I've never cracked the cases on one of these bikes either.  Hopefully that will get you past your "sticking point",

Thanks for the tip!

[curemode2002]

The Rotor should be what is holding it together. One thing though with these rotors especially those that have not be rebuilt they are very sensitive to vibrations. If you can keep threading the axel in it will pull the rotor off it is just a compression fit. Also you can get a puller that works great too here is the link it says it does not fit ours but this is the one I had to pick up.

https://www.denniskirk.com/dennis-stubblefield-sales/flywheel-puller-18mm-x-1-5-r-h-internal-male.p281961.prd/281961.sku

[Tom Witt]

The Rotor should be what is holding it together. One thing though with these rotors especially those that have not be rebuilt they are very sensitive to vibrations. If you can keep threading the axel in it will pull the rotor off it is just a compression fit. Also you can get a puller that works great too here is the link it says it does not fit ours but this is the one I had to pick up.

https://www.denniskirk.com/dennis-stubblefield-sales/flywheel-puller-18mm-x-1-5-r-h-internal-male.p281961.prd/281961.sku

Good info. Thanks! Unfortunately I no longer have the axle. I may need to borrow a puller from a friend.

[thrutheframe]

The Rotor should be what is holding it together. One thing though with these rotors especially those that have not be rebuilt they are very sensitive to vibrations. If you can keep threading the axel in it will pull the rotor off it is just a compression fit. Also you can get a puller that works great too here is the link it says it does not fit ours but this is the one I had to pick up.

https://www.denniskirk.com/dennis-stubblefield-sales/flywheel-puller-18mm-x-1-5-r-h-internal-male.p281961.prd/281961.sku

Good info. Thanks! Unfortunately I no longer have the axle. I may need to borrow a puller from a friend.

If a few little taps make the rotor go bad, it was already bad.  Any bolt with the correct threads will work to get it off unless its rusted in place.  It's sitting on a cone shaped reciever on a the end of the crank, they usually come right off.

[Hush]

Turn the casing upside down and clear away any dirt, you may have missed a tiny bolt.
I've ruined a few cases over the years because I never saw that last flippin bolt under some crud.
If you have the oil pan off check in there, can't remember if there is or isn't a couple of bolts in there that go up into the top casing?

[curemode2002]

The Rotor should be what is holding it together. One thing though with these rotors especially those that have not be rebuilt they are very sensitive to vibrations. If you can keep threading the axel in it will pull the rotor off it is just a compression fit. Also you can get a puller that works great too here is the link it says it does not fit ours but this is the one I had to pick up.

https://www.denniskirk.com/dennis-stubblefield-sales/flywheel-puller-18mm-x-1-5-r-h-internal-male.p281961.prd/281961.sku

Good info. Thanks! Unfortunately I no longer have the axle. I may need to borrow a puller from a friend.

If a few little taps make the rotor go bad, it was already bad.  Any bolt with the correct threads will work to get it off unless its rusted in place.  It's sitting on a cone shaped reciever on a the end of the crank, they usually come right off.

Yup mine actually had the varnish or whatever it is insulating the wire flaking off so mine was shot hence why I had to remove it.

[mr-m37hods]

Hi all, sorry to revive this thread. 

I'm working on a CB650 project and currently rebuilding the engine. Trying to split the case as well, and found this information useful.

It might just be me, being paranoid but I'm removing the rotor: Is it reverse threaded? How are you guys preventing the crank from turning? Pistons are hanging out and don't want to damage. Sorry if this is a dense question.