Topic: Seized Engine Help! 1976 CB750F

[DuckFan]

Good evening,

I am attempting for the first time, to restore a 1976 CB750F.

A little background about me, I have no mechanical experience apart from replacement of various pumps and accessory engine parts on a truck.

The Problem:
While tearing down the top end to the camshaft, I noticed that the camshaft sprocket bolts are stuck in the vertical position, making the bottom bolt inaccessible to remove the sprocket from the camshaft. The camshaft won't budge. I then opened the alternator to try and move the rotor in hopes to move the camshaft enough to reach the bolt but it wont budge.

Does anyone have any tips or advice for removing the chain to proceed with the teardown?

Thanks,
Duckfan

[enwri]

If you remove the tensioner spring assembly off the back of the cylinder, there might just be enough slack in the chain to work the cam around a tooth at a time to get the bolt where you can reach it.

[DuckFan]

Thank you for your reply!

I did that during the disassembly. I've been following the Clymer manual procedures thus far.
I've also removed the rockers and camshaft retainers.

[Jerry Rxman Griffin aka MuthaF'er]

Unless you can determine why it won't rotate and if all else fails, cut the cam chain. Replace it with the Tsubaki Camilla heavy duty one found on Amazon for around $30 

[DuckFan]

Should I spend on a chain breaker or bolt cutters? Will one be used more than the other later on?

[Jerry Rxman Griffin aka MuthaF'er]

Whatever is easiest and cheapest. You need a new HD cam chain anyway 

What's the history on the engine? Loosen all the rocker arms then see what happens.

[mashfu]

Not sure the exact position it came to rest for you but mine was a pretty bad angle too, i was able to position the open end of the wrench and slowly bring the bolt out as to not drop it into the case. And what Jerry said, I loosened/tookoff as much as I could from the rockers. It was pretty awkward but it did come out without cutting.

[rb550four]

If it's seized, You'll be rebuilding it anyways. Hollow out a spark plug , screw in a grease zerk, and push a piston down with the grease pressure. Once the grease pushes the piston down , there will be no need to hammer the pistons loose , the cylinders will be ready to slide off.
  Piston goes down, spins the cam, take the bolts out of the cam, remove cam....Tear down , clean the grease out and go about your rebuild.
Always works on 550's.

[DuckFan]

Thanks for the help everyone!
I managed to "rent" a chain breaker from harbor freight. I managed to break the chain and pull off the head to uncover the horror that is the cylinders/frozen pistons. Looks like I'll be getting a gear puller and unfreezing a couple pistons that way. I'm glad it was horrible to learn more about rebuilding.

Again, thank you everyone for your help!

[Jerry Rxman Griffin aka MuthaF'er]

Split the cases. Remove the rod caps. Dump the top end and start over. Plenty of cheap stock rods available in addition to the cylinders and pistons.

Is the head and cam still good?