Topic: CB550K noises

[SamP]

Video of the play in the primary chain.
Cb550 Primary chain slack

Video of the play in the piston rods.
Cb550 piston rod play

I have a video of the transmission sitting in the inverted top end, everything seems to move smoothly. I'll upload that one later if anyone thinks it's pertinent.

In the meantime, here're the crank bearings.





As you can see, primary chain is not slapping the case:


Other bearing homes:



Dave - it sounds better hot for sure, but I was still hearing the clunks in the case. Video feels pretty accurate, at least the one on my phone does.
My manometer is 4 glass bottles linked together in a loop (1-2-3-4-1) and then a separate line connecting each bottle to its carb. I ran it for about 5 minutes after tuning until the levels did not change significantly. Side note - I tried tuning it before I knew the floats were inverted. The SLIGHTEST touch of the adjustment screw would reverse the flow violently. I had no idea it would be that difficult! Then I disassembled further and found the issue.
Original clutch was installed still, I believe. Significant wear on the plates, but I have new ones to install. Adjusting the arm on the outside fixed the the CLUNK it made into 1st, but otherwise shifting was smooth. Didn't alter the rhythmic clunk of it running.

Jonda - I intend to replace this chain if that's the rattle. I'll let the forum decide of the play in the chain warrants it (I think it does, but this is my first engine tear down).

[dave500]

good the case isnt touched by the chain,that sort of rod wobble is acceptable from side to side,see how they plasti guage.

[bryanj]

Primary chain is worn but not totaly shot and i repeat that there is no way for the chain to be slack enough to jump a tooth unless its worn enough to have come out of the cases. Impossible to diagnose noises over the net but whatever it is it ain't the chain jumping

[SamP]

I was trying to go by spec, which Clymer's says is 1000. It's at 1100 or so in the video, and it still sounds like it's labored.

That's why I said I don't get distracted by the tacho needle.

I see what you mean now. I'll try to focus on how she sounds running, vs. where the tach is supposed to be.

good the case isnt touched by the chain,that sort of rod wobble is acceptable from side to side,see how they plasti guage.

I'll check back when I get them in. I'll also measure the pistons and bores to make sure they're in spec - I don't know how they could have gotten so scuffed.

Primary chain is worn but not totaly shot and i repeat that there is no way for the chain to be slack enough to jump a tooth unless its worn enough to have come out of the cases. Impossible to diagnose noises over the net but whatever it is it ain't the chain jumping

I think that was Jonda, I know my chain isn't jumping. I will definitely replace it and the cam chain while it's open.

[SamP]

Just an update while I wait on more parts:

Plastigage checks out on all the rods on the crank well within spec. Could not check the crank in the journals because those clearances were to the ten thousandths and the smallest plastigage I had was speced for thousandths (correct me if Clymer's added an extra digit to the clearance there). Since the clearances were so good on the piston rods, I feel comfortable with leaving those unmeasured. Feel free to slap some sense into me if this is something I shouldn't overlook - crank looks fine and smooth, no scoring or anything on the journals, just light wear you'd expect for the mileage.
On a side note, anyone have any suggestions for torquing the rods back on to spec? The rounded form of the bottom end of the rod doesn't allow for the socket to fully lock on, so I end up stripping the hell out of it if I use anything other than vice grips. They're already questionably marred as it is.

Calipers came in the  mail and the pistons are well within spec, as are the cylinders. I think the scoring may have been from (some idiot) revving before it was fully lubed, but I'm not sure. I filed the rings  (carefully) without a ring filer, but there were no burred edges that I felt when I installed them. Thinking I'll need new rings, but I'm not sure if I should reuse them and the pistons or if I need to get new ones of one or both - the scoring is barely enough to catch a fingernail. I just ran some scotchbrite over one of the skirts really quickly and I got rid of about 90% of the scoring, that's how light it is. I'm sure I can hone the scoring out of the cylinder wall. Advice? I'm not sure how any of these should look after 50 miles and a few hours of running after new rings and a fresh hone.




On a whim I decided to use my new calipers to check all the inner and outer valve springs. ALL were under spec by about 0.3 - 0.4 mm. Spec is spec, but is $100 on new springs really necessary? Or am I just being cheap and trying to rationalize it?

Exhaust valve I ordered was incorrect size (short 2mm) so I'm sending it back and have ordered a new one. One step forward, two steps back.

[bryanj]

If the con rod bolt nuts are marked get new ones and use a 1/4 drive or maybe a 3/8 drive 6 sided socket with apprpriate upducers to torque wrench

[SamP]

The problem is that the socket cannot fully engage because of the rounded bottom side of the con rod. It curves up just enough to make it impossible for the socket to seat fully. And I didn't destroy them, but the nuts definitely have some chew marks. Hardware store didn't have the right pitch, so now I need to find a source if I'm going to replace. And I'd like to know I have a foolproof way of getting them back on with proper torque before I order replacements (which I haven't found yet).

[jonda500]

Grind down the outside of a socket until it goes all the way on

[bryanj]

Sam I have rebuilt lots of these and a standard 3/8 or 1/4 drive socket will fit.

The nuts are specials and have to come from Honda

[SamP]

I've sourced them, but my socket was definitely too thick. If I don't buy a new one, I'll need to grind it down.

Sent from my Nexus 5 using Tapatalk

[SamP]

Just wanted to update everyone on my project. Figured I'd do it back on my original thread in case anyone with a similar issue comes looking for some sort of resolution.

Here's where I started, with the noise I was concerned about -

I swapped out the primary chain, cam chain, and transmission countershaft and its bearing. Two of my valves felt kinked, so i swapped them out. Put it back together, and after crossthreading the spark plugs, replaced the head (yeah, I was pissed). Used the formula to rejet my carbs (MAC 4 into 1, foam filter in stock airbox) with a #45 (previously #42) pilot and #100 mains (previously #90), set the float height to spec, idle mixture screws at 2 turns out. Put the battery in and this is what she sounds like now:

Now just the basic stuff - vac sync the carbs, hondaman ignition, update some wires and brakes, then work on painting the tank.

Thanks to everyone in the forum for helping with my myriad of issues during this rebuild. I wouldn't have thought I could tear down an engine and put it back together, much less have it actually run. I'll gladly answer anyone's questions if anyone has any, and will post more videos once she gets more functional

[Tews19]

Where did you get the primary chain?

[jonda500]

They're available on ebay:

http://www.ebay.com/itm/Honda-New-350-Primary-Chain-400-500-550-650-CB350F-CB400F-CB500K-23131-426-003-/331342410918?category=177980&buyerid=OT1C29eGPzQwfvEP0yg4Zw==&emailtemplateid=82132564&sellerid=FpRekKD1aqC5GKifmtiHlQ==&refid=store&ssPageName=ADME:B:SEMK:US:SHOWI

[SamP]

David Silver Spares:

http://www.davidsilverspares.com/CB550K-1977-USA/part_144813/

[Peterengland]

+ 1 on just raising the idle revs to 1800 or so. Mine was making noises and a carb sync got rid of 50% of the noise, then I replaced all the carb boots and clamps and now there is hardly any noise at all, don't be too tempted to try and get the bike to idle too low, there is some competition to see how low some can get them to go, but who cares? also with these Hondas they are known for some clack.

[TwoTired]

If your tach is accurate 1800 is just too high.  If you need that after a full tune up, there is something wrong, imo.

Honda made the engine to idle at 1000, +/- 50 rpm.

If compression is equal, and cam is working as it should and the tappets are properly adjusted, then noise is coming from unequal carbs (or filtration), even if vacuum sync is proper.

[SamP]

Yeah, mines at around 1200-1400 when it's warm. Cylinders range from 120-125 psi and the rings haven't set yet. I'll try and get the idle dialed in once I know the carbs are where they should be. Doesn't sound like I should have a problem anymore with the noise and stalling, since I think it was fuel related (inverted floats, incorrect jets, one dead plug at time of purchase). Just trying to figure out how far out my idle knob should be. Advice?

[TwoTired]

All the idle knob does is stop the downward movement of the slides.  This assumes the individual adjusters haven't been skewed to prevent full downward slide travel in the carb bores.

The knob doesn't care what position it is in.  It's just set to achieve the idle speed you want.

If you bench sync'd the carbs with a drill bit, it is often set wrong and won't allow the slides to reach the "floor" of the carb bore.  Then the idle knob can't properly set the idle speed low enough to meet specification.


If you used an auto or diesel compression gauge, that easily explains why your compression numbers are low.  There is a FAQ entry about this.