Author Topic: 1977 CB550F IDK (first build) (Read 173454 times)

calj737 · « **Reply #575 on:** November 11, 2015, 12:32:24 PM »

$:-\$ My guess is cam chain

Check the adjuster bolt under the carbs. Release the nut, and see if it adjusts any by pressing the slot with a flat blade screwdriver. Then, remove the #2 intake tappet, and look in and see if you can visibly see the chain in tact. Else, remove all the tappets, release the valve tension, and lift the cover off the head.

If you find the chain is split, leave it in place and thread a new one onto it and hopefully you can pull it around and then fasten it with a link. Else, the head is coming off. (IF this is your problem)

minimo · « **Reply #576 on:** November 11, 2015, 01:32:41 PM »

Man, I'm a little afraid to check...

The idea behind the cam chain tensioner is that it's spring-loaded, so when the adjuster nut is loosened, the slotted screw bit self-adjusts to put pressure agains the chain, and then you hold the screw in place and tighten the nut, is that not correct?
Perhaps I didn't get that right?

calj737 · « **Reply #577 on:** November 11, 2015, 01:34:23 PM »

Close enough. It self adjusts due to spring tension. Trying to press the blade with the screw driver may tell you it's bound up or not. It's a quick and easy test to prepare you emotionally if you happen to find a snapped cam chain later.

minimo · « **Reply #578 on:** November 11, 2015, 01:45:40 PM »

I get some movement on the cam chain adjuster... Minimal on pushing the screw but it can turn a little both left and right with slight/sluggish return.
I removed the #2 inlet tappet and there's no visibility of the chain; neither on #3 inlet nor outlets. I imagine there'd be a window if I removed the whole carb assembly rack??

calj737 · « **Reply #579 on:** November 11, 2015, 01:51:37 PM »

No to the carb rack. You'll have to remove the rocker cover if you intend to get a full view of the chain. Argh...

minimo · « **Reply #580 on:** November 11, 2015, 01:53:08 PM »

Argh

Thanks, calj737. Report back tonight (PST).

SOHC4 Cafe Racer Fan · « **Reply #581 on:** November 11, 2015, 02:37:26 PM »

"How'd you get the beans on top of the frank?"

I feel your pain. Hopefully if it's a broken cam chain, it didn't do too much damage before seizing the motor.

SOHC4 Cafe Racer Fan · « **Reply #582 on:** November 11, 2015, 02:38:35 PM »

Oh, and I've lost the other chain, too. Lucky it didn't take out my Achilles or seize the rear wheel. I had a sprocket lose a tooth or two and throw the chain.

minimo · « **Reply #583 on:** November 11, 2015, 02:41:49 PM »

Thanks, CB750.

Ha, had to look up that reference. Ha, classic! Yeah, that'll pretty much sum this up.

SOHC4 Cafe Racer Fan · « **Reply #584 on:** November 11, 2015, 03:36:08 PM »

minimo,

Whatever happened can be repaired or rebuilt. You have already done the hardest part, and all of us have experienced a big step backward.

Hang in there!

Don

minimo · « **Reply #585 on:** November 11, 2015, 03:36:56 PM »

Cheers, Don!

The going theme throughout this build has been "four steps forward, two/three steps back."

goldarrow · « **Reply #586 on:** November 11, 2015, 03:45:13 PM »

I'm curious as to what causes the wheel to lock up, can't wait to see your finding.

minimo · « **Reply #587 on:** November 11, 2015, 07:08:20 PM »

Well, we're on to something here:

Teeth from the cam sprocket is my guess. Hopefully that's all it is. Gonna pop the cam cover to dig deeper...

minimo · « **Reply #588 on:** November 11, 2015, 07:14:06 PM »

#shards

goldarrow · « **Reply #589 on:** November 11, 2015, 07:17:51 PM »

Wow. Just when you fixed something, then something else happen. Those don't look like cam sprocket teeth though

minimo · « **Reply #590 on:** November 12, 2015, 12:52:46 AM »

Treating this investigation like an onion.

First, peeled back the cam cover to reveal everything as normal. Then came the cam sprocket and cam (oh, what fond memories). So far so good there - I could even turn the engine from this point, but nothing broken yet and looking down the cam chain void I could see no noticeable sign of wear. Removed the carb rack assembly and exhaust. Holy 550 communion time with the rubber pucks to reveal the six header nuts (I'll have to replace these pucks, amen).

Popped off the header - thank goodness my gaskets are still clean and seemingly reusable.
Removed the cam chain tensioner and guide. This is where I noticed something a little off with the chain tensioner. A while back I had to replace the part 'cos I somehow broke the thread off of the adjuster bolt but now, having the two I compared them...

My original one on top and replacement on bottom. Did the replacement bend a little during the mishap, perhaps? Was this the design of some of the earlier 550s? Here's another look at them stacked on top of each other, the replacement on the bottom (a slight angle up compared to my original). Should this make any difference?

Anyway, onward with the investigation. Pistons and rings are all still looking good and even the cam chain looked fine. Since I was able to turn the engine, I gave a look on the underside of the engine case and there it was, the wreckage:

Gear on the right. Whatever it was knocked the hell out of those teeth! What could have caused this? I was shifting fine up to fifth. Things happened fast when the mishap occurred but I do remember for whatever reason I was downshifting from 5th to 4th and I was slow on letting go of the clutch; I think I wanted to downshift slightly and that's when the weirdness happened. First a clink, then a thud, and then a thunk and rear wheel locked up...
Crap. What now? Keep peeling back, I suppose? I gotta get that gear out. Do they even sell replacement parts? Should I be looking into getting another engine?

Check out this gangsta lean

I'm getting the hang of this rebuild. All this peeling only took a couple of hours (with some distractions in between).

Meanwhile, feast your eyes on my early Thanksgiving smorgasbord.

calj737 · « **Reply #591 on:** November 12, 2015, 04:55:07 AM »

Ouch! Let me know if you need a new trans. I may have one sitting around, already extracted from an engine. If not, I've got a spare motor that I can pull down for you on Sunday and ship out Monday perhaps.

I've got no idea how that would have occurred, but something isn't right in there.

Stev-o · « **Reply #592 on:** November 12, 2015, 05:08:38 AM »

Sorry to see, that is not very common. Did you have the lower case open previous?

BTW - don't reuse exhaust gaskets, they are a 1-time use.

SOHC4 Cafe Racer Fan · « **Reply #593 on:** November 12, 2015, 07:30:57 AM »

Keep peeling the onion. Something doesn't smell right to cause that kind of gear damage. Hopefully, just a gear or trans replacement. Also that cam tensioner is clearly bent.

minimo · « **Reply #594 on:** November 12, 2015, 09:41:43 AM »

Thank you very much for the offers, calj737. I am tempted to take you up on them. I will let you know, but there is no rush. Like CB750 Fan is saying, I'm going to keep peeling the onion. I've taken the build this far, and yes, Stev-O, I have had the lower case open previously (by yours truly) so I want to learn what I may have done or installed wrong.

I'm tempted to swap out the engine and call it a day. That not only sounds easier, it'd probably be a lot safer at this point. But I can't help wanting to dig deeper for discovery, which is what this whole build is about anyway (not to mention digging deeper into my pockets, sheesh).

Thanks for the heads up on those exhaust crush gaskets, Stev-O. I will change them.

Anyone have any opinion of my cam chain tensioner? No big deal/still useable?

Sent from my iPad using Tapatalk

knowsnothing · « **Reply #595 on:** November 12, 2015, 12:05:23 PM »

Quote from: minimo on November 12, 2015, 09:41:43 AM

I'm tempted to swap out the engine and call it a day. That not only sounds easier, it'd probably be a lot safer at this point. But I can't help wanting to dig deeper for discovery, which is what this whole build is about anyway (not to mention digging deeper into my pockets, sheesh).

Sent from my iPad using Tapatalk

Sorry to hear about your troubles. It will make it that much sweeter once you get it all worked out.

If i was you, I would do both. Swap the engine AND keep peeling the onion and repair that one too. That way you get to ride and have something to wrench on and when its back together, you have a spare!

minimo · « **Reply #596 on:** November 12, 2015, 12:11:02 PM »

Quote from: knowsnothing on November 12, 2015, 12:05:23 PM

Sorry to hear about your troubles. It will make it that much sweeter once you get it all worked out.
If i was you, I would do both. Swap the engine AND keep peeling the onion and repair that one too. That way you get to ride and have something to wrench on and when its back together, you have a spare!

I like the way you're thinking...
I'd heed your advice if storage/space weren't issues with where this is all taking place...
calj737, can you give me a sweet friendly deal? Is your engine a '77 550F?

goldarrow · « **Reply #597 on:** November 12, 2015, 12:13:35 PM »

Quote from: minimo on November 12, 2015, 12:11:02 PM

Quote from: knowsnothing on November 12, 2015, 12:05:23 PM
Sorry to hear about your troubles. It will make it that much sweeter once you get it all worked out.
If i was you, I would do both. Swap the engine AND keep peeling the onion and repair that one too. That way you get to ride and have something to wrench on and when its back together, you have a spare!
I like the way you're thinking...
I'd heed your advice if storage/space weren't issues with where this is all taking place...
calj737, can you give me a sweet friendly deal? Is your engine a '77 550F?

Just one more engine in the garage won't take up too much space, not like you have 6 more bikes sitting on the back burner

minimo · « **Reply #598 on:** November 12, 2015, 12:14:39 PM »

Ha! That sounds familiar. I think I've seen such a place, eh, goldarrow?

calj737 · « **Reply #599 on:** November 12, 2015, 12:41:48 PM »

The spare I have isn't assembled and running. It's a parts engine to breakdown and provide indiscriminate parts to those in need.

I have a running 550 in my 74 that I'm building a replacement for. But I don't think you want it shipped cross country. That would be expensive I think?

Pull the engine, split the cases, and replace the trans. I can pull my spare down and ship that out to you lickety split.

News:

Author Topic: 1977 CB550F IDK (first build) (Read 173454 times)