CB550 teardown - Stuck Again

[elmalo68]

WHERE I'M AT: : I'm doing a complete teardown of a '74 CB550 motor. The engine seized long before I owned it. Also it appears that the engine was painted as one solid unit at one point in it's life. Haven't been able to remove the cylinder head – pistons won't move. I soaked them down in WD-40 and while that has penetrated completely, still no joy. Plan B was to separate the crankcase and try to dismantle from the bottom up.

NOW: According to the manuals (I have two different), I have taken off all the components that need removing, but I still can't get the crankcase to separate.

Any one have any useful ideas or tricks?

 

[elmalo68]

Right side.

 

[elmalo68]

Left side.

 

[Hot500]

Have you removed the long bolt from within the sump area. 10mm head from memory. It threads up from the bottom case and is easily overlooked.

 

[elmalo68]

BINGO!!!

 

[smarsh]

You'll have to pop out the primary shaft at some stage to remove the crank. One of the rear engine mount bolts(if you have it) can be threaded into the end of the primary shaft, and be used as a slide hammer with a large socket.

 

[RedRider]

Hey, how's the teardown going?

 

[elmalo68]

It's completely torn down at this point, but I haven't done much with it since. Everything I do now, is going to cost money. Being my first build, I'm not sure what my next step in the whole process should be. Do I start with the frame or with rebuilding the engine?

 

[smarsh]

Depending on what you find inside the motor, a rebuild might not be necessarily costly. Personally I'd rebuild the motor first, that way if it turns out that your motor is ratshit, you won't have wasted money on a frame you can't use.
Depending on what caused it to seize, and how the bottom end internals look.

 

[elmalo68]

Other than the pistons and the valves, everything else looks to be in good working order. However this being my first project, it could simply be a case of me not knowing what the hell I'm looking at.

The crank and the cam look look good to me, but I'm guessing I'd still have to measure the bearings to make sure?

 

[smarsh]

If you've got another thread you're gonna use as a build thread, send me a link. Otherwise throw up some pictures of the parts in here.
Camshaft - Check the journals for any strange wear marks or grooves. Check all the lobes for pitting and scoring. The journals in the head itself aren't replaceable, requires a whole new head. As long as they haven't been starved for oil, and don't have any major scoring you should be right.
Valves - you'll be surprised as how much they'll clean up with a brass wire wheel. As long as they aren't bent, pitted, chipped, they're generally OK.
Pistons - Have you been able to get the motor to turn over, to see why it was seized? Have you got the cylinder off yet? Pistons and bore will need a good inspection, and the bore to piston clearance will need to be checked.

As for the bottom end, you'll need to have a good look at all the gears and dogs, the shift forks, make sure there's no pieces broken off or showing major sign of wear.
You'll have to check the big end bearing (conrod) and the main bearings. If they look reasonable, no major scoring or wear marks, then you check the clearances using Plastigauge.
You'll also want to check to see if the primary chain has been rubbing on the cases.
New seals would probably also be a good idea.