CB550 NEED HELP - tearing down an engine that won't turn

[elmalo68]

So a few months ago I bought a 1975 CB550 that was little more than a roller. The engine didn't move freely at time of purchase and I knew that going in. I bought the bike mostly to learn from, but I'd like to do what I can to bring it back to life.

I'm in the process of tearing down the engine. After removing the valve cover, I'm pretty much stuck as I can't figure out how to remove the camshaft since the engine won't turn. The bolts on the camshaft sprocket are positioned in a way where it's tough to get a wrench seated properly. I'm also getting no slack when I release the tension on the chain.

I thought about trying to pop a link on the timing chain, but I want to do my best to save every usable part that I can. Any help is appreciated.

 

[teazer]

You will want to replace the cam chain anyway. It's a consumable item. Grind the head off both pins on one link and punch/press out the link and go form there. The whole motor has to come apart anyway, but try to mask off things when you do the grinding. The less unwanted metal shavings inside, the better.

 

[elmalo68]

Sounds good. Thanks for the advice.

 

[Hot500]

Why doesnt the motor turn over? The photo in your post shows a fairly clean looking engine. Has it been exposed to the weather?

Sometimes these things have a simple explanation. e.g. bike has fallen on its gear lever side and bent the gear selector shaft, or pushed it up against the back of the clutch basket preventing the motor from turning. Is there any movement at all?

If your sure the pistons are seized in the bores, a good soak in deisel for a week will work wonders for freeing things up.

 

[alzcbz]

One of my spare motors was locked up. It was missing the starter. It so happens that when I pulled the covers on the stator side of the motor, the chain for the starter was wrapped around the crank and jammed up. Pulled the stator and chain out and the motor was free. Just sayin.

 

[elmalo68]

Why doesnt the motor turn over? The photo in your post shows a fairly clean looking engine. Has it been exposed to the weather?

Sometimes these things have a simple explanation. e.g. bike has fallen on its gear lever side and bent the gear selector shaft, or pushed it up against the back of the clutch basket preventing the motor from turning. Is there any movement at all?

If your sure the pistons are seized in the bores, a good soak in deisel for a week will work wonders for freeing things up.

The motor seized at some point prior to my owning the bike. I have the top end torn down to the cylinder block now. I'm waiting on the PB Blaster that I sprayed at the top of the pistons to soak in for a few days before continuing disassembly. After pulling the head off, this is what the valves looked like (see picture). I don't have enough mechanical experience to diagnose what happened, but it certainly doesn't look good.