Topic: CB550 Valves Hanging Up??

[Dr. Frankenstein]

Okay, this is some bad juju right here - I thought today was going to be a start day for my 74 CB550, but it's not - here's what's happening: I installed an electronic ignition, no worries there, but the same problem I had even before I changed it out  - and caused me to rebuild the engine AGAIN - has surfaced, and I don't know why.

I turn the bike on, hit the starter and it makes this really nasty "CLACK"ing sound in the engine, like it's tripping over itself/sounds like a box of rocks, AND I see some of the valves/rocker arms hanging up briefly!    I'm horrified, take the plugs OUT and turn the engine over with the start button and she spins over smooth as silk! No Scary Noises, all the valves go up and down...I checked the plugs (D7EA) and they're not bashed in, so I don't think the plugs are hitting the pistons...I know I set the camshaft correctly and the engine spins over by hand just fine...  What is causing this?? If the valves were hitting the pistons, wouldn't you hear it even without the plugs in...??

Plugs IN - Scary Noises
Plugs OUT - it turns over fine.

I'm going to snake my borescope down in there and see what's what, and pray my valves are not bent...that nasty noise I get with the plugs in doesn't sound like it's coming from the valves area though, more like down inside, but I will report back.

UPDATE: Nope - I have a Vevor articulated borescope that I can stick down in cylinders and literally look around and even back up the way I came in/reversible, and everything looks fine; no chips, impact marks or anything else that I can see that would create that ugly racket - I'm stumped.

[bryanj]

When you fitted the cam cover did you use the rubber bands and rear the manual carefully, if not you may well have bent some valve stems and/or broken valve guides

[Dr. Frankenstein]

Clarify 'rubber bands' - I didn't take anything out that didn't go back in. I also made sure that the rocker arms were free and clear so I could put the cover back on easily, with the gasket in place.

But let's just assume for the moment I did screw something up - why does the engine spin over beautifully with no spark plugs in, and yet sounds horrible with them IN? The spark plugs don't move, do not interfere with the valves, and are not hitting the pistons. This is an interference engine, right...?

[HondaMan]

I've heard a similar sound in a 750 that had a bad roller in the starter clutch. It had a flat spot on it, and when the starter was spinning the clutch alternately engaged, slipped, then re-engaged. It was real noisy and sounded real serious: it just had a bad roller, with a flat spot on it.

See if you can determine if the sound is coming from the alternator cover?

[bryanj]

If the valves are hanging slightly the compression with plugs in could make them snap shut, the rubber bands is a well known tip on 500/550 to hold the valve end of rockers up whilst tightening cam cover, it is possible to have the adjuster tip alonside the valve stem and when you tighten the cover you bend the valve over

[Dr. Frankenstein]

No, I made sure all the rockers were situated over the valve stems when I got it back on before I tightened it down, as the book mentions; and I'm kind of anal like that..

HM - "...when the starter was spinning the clutch alternately engaged, slipped, then re-engaged. It was real noisy and sounded real serious..."

All things being equal, that's exactly what it sounds like - A bad roller. FML. I say this because for a few turns of the engine (and I didn't do this a lot) it sounded exactly like the clutch engaged, slipped and re-engaged - - like my old Virago, in which a bad starter gear (the #2 idler gear) would bounce off the flywheel a few times before it engaged, sounding like a box of rocks...

I'll bet you it's that - a bad roller in the starter clutch...one of those things you don't really notice...and there's no easy fix, is there, except to take it out, replace the rollers and reinstall...or is there an easier fix??

"Help me, Obi-Wan, you're my only hope...!"

And Again - "why does the engine spin over beautifully with no spark plugs in, and yet sounds horrible with them IN??"

The interwebs say this could be caused by a 'loose clearance in the clutch basket'...so maybe I just need to check my torque values...? No idea. But again: "why does the engine spin over beautifully with the spark plugs OUT, and yet sounds horrible with them IN??"

[bryanj]

You have to remove lower case to do starter rollers but top end can stay in one piece.
Whilst the primary drive is out it is worth changing the rubber dampers as the get hard with age.
Again worse with plugs in as it has compression so starter working harder

[Dr. Frankenstein]

Uhh..."you have to remove lower case to do starter rollers but top end can stay in one piece".

'Remove the lower engine case...but top end can stay in one piece'??

Of course, if I'm off base here, please explain how I would 'remove the lower engine case' and leave the top end in one piece...?

No worries Bryan, I drink too....

[jonda500]

My 2nd 500 has always had a bad starter clutch (since I've owned it). I have completely given up using the starter motor to start it - I just use the kick starter!
If I try to electric start it when the engine is cold it just makes a really horrible noise, once it is fully warm it will electric start.
John

[HondaMan]

Yep, Bryan's explaining it: the primary drive subsystem (Section II - Page 15, middle right on the page shows the clutch) also mounts the starter's clutch. Honda learned a bit of a lesson there from the 750: the rollers really DO need some oil now and then, and the 750 runs them dead dry.

Have you had the bottom end apart before, in this journey?

[scottly]

There is a thread about replacing the starter clutch on a 550 without splitting the cases somewhere...

[Dr. Frankenstein]

Johnda - Good to know...! I might try that!

HM - Good to know about the starter clutch; perhaps I owe Bryan an apology... but I would think that some of the splash from inside the case might/would keep the starter clutch lubricated?? That's just a supposition...and Yes, I've rebuilt this engine twice because of that noise, and I really do not want to do it again if I can help it.

Scottly - It'd be great if you can point that out...

[scottly]

It took a while to find it.
http://forums.sohc4.net/index.php/topic,122084.0.html
BTW, does it make the noise if you use the kick-starter?

[HondaMan]

Wow, I remember reading that thread, forgot all about it! I suspect it might not work if a brand-new primary chain has been installed, but haven't tested that theory myself? It's got very little 'slack' with a new chain in there, which might make the twist & out move tricky? Still, it's cool he could do it in-engine.

I might try it with my 350F when i get to the back-together phase, just to see.

[bryanj]

Dont know about 350 but on 400 i just did i had to take a bearing out to remove the spacer and get enough room to disconnect the primary drive.

Never tried the 500 via the sump, i have big hands and arthritis so its no chance.

What i meant was no need to remove the head, cylinders etc to remove lower case, yes all the clutch and gearchange has to come out

[Dr. Frankenstein]

Scottly - YES!! That is exactly how it sounds when I crank it! Thank you so much for that video! The bike is currently on a lift table, but I'm wondering if I should put it on the floor to do this...still - whoo-boy...

Meh - what else do I have to do, y'know...? It's not running now anyway...Good to know it can be done without tearing everything apart again.

I've seen a few other posts pertaining to this too - Is this a common problem with these bikes??

[bryanj]

Not common, can happen if stood for a long time or oil not changed enough/wrong grade or type.

These are old now so happening more often, 450/500 twins was commonas fell apart and 750 not unheard of but others not so often

[Dr. Frankenstein]

Still, why does the engine turn over fine w/o the plugs in, and I only get the noise when the plugs are In??

[denward17]

Still, why does the engine turn over fine w/o the plugs in, and I only get the noise when the plugs are In??

With plugs out, you are taking strain off the starter gears (compression).

[Dr. Frankenstein]

Welp - I'll let you know how it goes, when I get it done!

UPDATE: I am happy to report that Yes, It CAN be done! Doesn't take all that long either, all in all maybe an hour and a half to get everything off and out; the hardest part is getting the starting gear off the starter clutch while it's in the engine, that takes a bit of jiggling - but Yes, it can be done!  I found the problem, too - note the bent start clutch spring...that bothers me a bit because if you look closely, you can see the tip of that starter clutch roller was gone, making it look like a tube, unlike the other two. Next step is order the new parts and put it back in; shouldn't too hard (famous last words, I know)!

And Scottly - again - thanks so much for that video and procedure!

Question though - the only bike-specific source for this spring and roller kit appears to be 4into1, for $60 - these springs and rollers were used on a lot of different bikes. I am leery of ordering some from 4into1 because of their rather slipshod approach to bike parts, not to mention I think they are overpriced - do you have any recommendations for another stateside supplier that won't cost me triple b/c of these dang tariffs? Will any other Honda models work?

[bryanj]

As far as i know roller, pins and springs are still available from honda, i think nurse julie on here may do them as a set not sure

[scottly]

Honda learned a bit of a lesson there from the 750: the rollers really DO need some oil now and then, and the 750 runs them dead dry.

The 750 rollers are exposed to all sorts of oil mist, with the location behind the alternator rotor and the hub of the starter gear fed pressurized oil from a jet in the crankshaft.

[scottly]

I found the problem, too - note the bent start clutch spring...that bothers me a bit because if you look closely, you can see the tip of that starter clutch roller was gone, making it look like a tube, Will any other Honda models work?

The parts might be the same as all the SOHC fours? The rollers are the thick round parts: inspect them for wear lines running length-wise. The one that the side is visible in the pic looks OK? If they aren't worn, I would re-use them. You may just need 1 spring and 1 spring cap, the part that is now a tube.

[Dr. Frankenstein]

Yes, I was thinking that, and that is probably what I will do; I like to put in new parts when I can, but that would seem to be a more cost-effective way to go. I was also just wondering where people are getting their parts these days.

[Little_Phil]

As Hondaman was intimating. Interested in know how new is your primary chain? I don't think this is possible with a fairly new chain. Am building an engine at present and put the starter clutch in before putting the cases together and then primary shaft yesterday. Primary only had a few thousand miles on it and didn't look like there was enough slack. So was glad I placed clutch in first.
Glad you hopefully solved your issue.

[HondaMan]

Yes, I was thinking that, and that is probably what I will do; I like to put in new parts when I can, but that would seem to be a more cost-effective way to go. I was also just wondering where people are getting their parts these days.

I've used the ones from PartsNmore and VintageCB750 several times, work fine. Honda doesn't always have them in stock at South Sound Honda, which was how I first started using them. I had 4 CB750 engines in one winter (the winter of Covid) that all had at least one rusted starter roller, 2 of them had all 3 as slugs of dirt and rust. One of those had sat in a dusty, wet wooden shed for many years, while the other was on a 750K3 that was a running bike, but had very worn main bearings, indicating poor oil-change practice (and it had been using 10w30 oil for decades). The latter had a roller that could not rotate at all, being rusted in one position.

[Dr. Frankenstein]

I'm pretty sure it's the original chain, but there's not much slack in it - as the OP mentioned, you have to get pretty jiggily with it to get it to finally come out, and taking out the starter and all the rest gives you Just enough room to get it out; I was able to get the starting gear out of the starter clutch by leaning it a bit and then pulling it out, wrestled with the clutch for a bit to get it out of the chain and then it came out. Took a lot less time than I expected. I have a new spring and cap roller on the way to replace the damaged one, hopefully that will solve my problem - this bike's too pretty to sit!   

[bryanj]

Honest opinion you are making a mistake not changing the full set

[Dr. Frankenstein]

Yeah, maybe - Always time to do it twice...hopefully not; but I'm an optimist! 

UPDATE: Okay, so, after a bit of hunting I ordered a new roller and spring (roller - 28126-323-000 and spring - 28125-323-000 respectively) to replace the damaged one seen in the photo above, but when they got here I noticed right away that the spring was noticeably longer than the old ones, which I attribute to the old springs being compressed over time; okay, no biggie...but me being the stickler I am to buy bike-specific parts I noticed (1) the spring differences, and (2) noticed that the caps on the rollers weren't exactly identical. As you can see, the tops of the old caps showed wear (in the second pic, the new one is on the right), so I have another three of those on the way from the local bike shop at $6 apiece, but the new one's 'cap' (the one I received today) is not as tall as the other worn ones; the springs I had to hunt down and buy piecemeal online after they told me the springs are not made anymore.

K&L has a kit that supposedly fits a bunch of Hondas for $32, but noticeably NOT the CB550, although the rollers look identical; 4into1 has a kit for the CB550, but it's $60...although in retrospect I've spent about the same amount so perhaps the 4into1 kit was the better bargain - and Common Motor's kits are all Out of Stock! It was slightly maddening. And here's some pics for the eye candy...

My question is, are the springs and rollers for the CB550 interchangeable with any other bikes that you know of - (for instance the Honda Magna 750) - or do I / we have to keep getting bent over for new starter clutch parts for the 500/550?

4into1 has the springs for $10 apiece, but the part number is different: 28125-283-010 (the CB550 is not listed as a fitting part) as opposed to 28125-323-000...does that change in nomenclature make a difference?

   

[bryanj]

If you create a free account at cmsnl when you look up the part it will give a list of models that part fits to, some of those starter bits fit nearly 400 models.
500 and 550 are the same and i thought the 750 was but the part numbers are different so not sure now