I bought my first CBX 1000 a couple weeks ago. The guy I got it from was the 2nd owner and was restoring it himself. The bike sat since 1986 when he picked it up.He said he installed new piston rings and replaced some valves. While running the bike for the first time the cam chain (A) broke.
When I git it home I fixed some small things....signals won't work. Cleaned the rust out of the bulb housings and terminal ends, that fixed them. The clutch cable was rusted so I replaced that. I looked inside the fuel tank and saw that he painted the inside of the tank! & the paint was peeling. I removed the paint with Turco paint remover bought a fuel tank seal kit. I have the tank sitting with tank cleaner in it. The fuel petcock was replaced with a cheap one & it leaks internally so I have a stock one ordered.
The crankshaft turns freely and turns when the stater button is pushed. I tilted the engine and removed the cylinder head. I found the main cam chain broken & the exhaust valves for #3 & #4 cylinders are bent slightly. The cam chain guide I also found broken. When removing the oil line from the crankcase to the rear of the head I noticed the oil bolt to the head has no holes for the oil to flow into the head, it's a solid bolt. So I assume that was what caused the cam chain to brake...no oil to the head.
Well, you've taken on quite a project. Those are the correct bolts for the oil line. The top end was oiling. The reason you chain broke was like cams installed incorrectly. Unless you have a photo before you removed them, you'll never know for sure. But that's the classic '20 mile rebuild'. Cams installed 180 degrees out and the bike goes about 20 miles before the chain breaks. Usually a lot more damage - must have been a pretty low-rpm break. Good luck with it - you seem to have a handle on what you're doing
Look the top bolt (bottom one in your photo) to the oil line over carefully - you'll see it flows oil. The shoulder is machined so the oil flows into the head just under the sealing washer.
Thanks for the reply Dave. I took a closer look at the upper oil line bolt and noticed the shoulder you are talking about and can see that oil was in fact getting to the head. Before removing the Cams I noticed the intake & exhaust lobs for #1 & #6 cylinders were facing inwards (towards spark plug). Your right the Cams were installed 180 deg. out. I think the lack of damage is due to the fact the PO didn't take it for a ride, he started it, let it idle and was about to synch the carbs when the Cam chain broke.
I was wondering I've ordered a new Cam chain A, would you also replace the Cam chain B from EX Cam to IN Cam even though it didn't brake?
If you have access to a new chain, probably a good idea, but nothing wrong with using the old one either if miles were fairly low.
On the bent valves - carefully check the guides for cracks - they almost always do when this happens. So plan on new valves and guides in the affected holes. Also check the sump for case parts - usually the chain breaking will break off a bit of the lower crankcase, but causes no problem. Just make sure to clean the sump out, but I guess you'll be there anyway since you'll be splitting the cases to change the chain.
I ordered a DID rivet link Cam chain so I won't have to split the cases. I noticed some metal missing from the broken Cam chain links so I will be dropping the sump, I'll have a good look around when I do. I wasn't sure if I'd be replacing the valve guides from the bent valves so thanks for the heads up.
I suppose guys have had success with the split chain. As far as you are now, I'd really split the cases and do it right. You have to make ABSOLUTELY sure you do the rivet link right. Keep us posted.
I finished removing the paint from inside the fuel tank, removed rust and resealed the inside of the tank.
I've been looking for a Cam chain guide which seemed very difficult to find. I went to a local bike wrecker today. They had a complete engine in rough shape but they sold me the cam chain guide for $20! in perfect shape. I had to remove the head myself to get it but well worth it.
Yes they are willing to sell to whole engine, I'm not sure for how much though. I can find out if you want.
As far as more winter projects when my daughter was 1 years old I promised her I'd restore a 74 CB550K and when she turns 16 it would be hers....well she's 3 now and remembered I said that so I've also got that on the go.
I can only begin to imagine how heartbreaking it must have been for the PO to have done so much work only to have it go so terribly wrong so close to completion
Still, it seems to have worked out well for you, kudos ! The bike looks very nice otherwise.
BTW, I'm with Dave on the cam chain issue. These bikes don't respond we'll to half measures. Besides, I'd be forever fearful of a master link failure at the most inopportune time
Keep those updates coming
Hey guys I tend to agree with splitting the cases to put a new Cam chain in, it's just a lot of work. I may not have a choice anyways I went to the local bike shop today to pick up the Cam chain and what showed up was an endless chain with no master link and it was 124 link chain. From what I can gather the stock Cam chain (A) is 120 link so the shop is trying to contact DID to find the right chain. As far as a master link coming apart I'm not really concerned I work in aviation and have access to people who rivet for a living.
My question is though if I do have to split the cases do I have to remove the clutch and alternator?
More progress:
Cleaned the tops of the pistons and cylinder walls, cross hatching looks good.
The gas cap seal has many cracks, got a new one. The PO put an aftermarket petcock in which still poured out fuel in the off position so I got a new Honda petcock. The tank is 100% complete.
The throttle seemed stiff, the cables weren't salvageable so I have new ones on order. Even with the cables removed the throttle still seemed stiff. Disassembled it to find 34 year old grease and dirt. Took it apart, cleaned everything and now smooth as butter. I think I'll take apart the l/h switch assy. and clean it.
when my daughter was 1 years old I promised her I'd restore a 74 CB550K and when she turns 16 it would be hers....well she's 3 now and remembered I said that so I've also got that on the go. 
