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Kbongos 1972 CB450 K5 engine disassembly

stl360+450 said:
The one I've used is Klean Strip Concrete and Metal Prep from Home Depot. The Q&A page claims it is 10–30% phosphoric acid with about 2% alcohols, including 1% isopropyl. They don't specify, but presumably the rest is water. It's $17 for one gallon. (I really have used Coca Cola® for rust removal as well and it does a decent job.)
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Thanks, that looks better than the rust dissolver.
jensen said:
Yes, the rust-oleum will do, all these rust removers are based on Phosphoric acid, with some different additives per brand. I like the pressed air route used for pressing the acid through the rust layer, but be careful keeping the pressure relative low and use a pair of safety glasses. Pressure per square inch can be very high, fragmenting the plastic in small pieces when exploding. To avoid this, people use grease, the effect is the same, but safer. Ever pushed out a brake cylinder with pressed air ? There is still a hole in my wooden ceiling (18 mm thick plywood).
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I did put on the safety glasses, and I am skeptical about the plastic cap, I am aware of the hazards of air pressure but have never experienced it. A brake cylinder shot through the roof would be a frightful warning. I've heard accounts of air compressors blowing up, due to rusted tanks. And then there are exploding truck or car tires that can take you out. I understand they have protective metal cages for servicing large truck tires. I stand to one side when putting air in my car tires now, and squint my eyes, look the other way(for extra safety). I walk away from that air compressor under my table, I should probably put it behind some protective barrier. Some day Darwin may catch up to me.
 
I've used HCL based toilet cleaner ( Harpic Max Power ) and this removes rust from inside fuel tanks very quickly. The down side is that the cleaned steel surface flash rusts as soon as you wash off the toilet cleaner with water. I prefer phosphoric acid, it is readily available on Amazon here in the UK. Once it has removed the rust you can simply swill the tank out with some fresh phosphoric acid, drain and allow to dry, preferably using hot air. Tank then ready for use, or ready for application of tank liner.
 
I suppose just using a hole saw to destroy the piston is not an option?

Crude, but effective.

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Liner survived, I then had a +1.00 mm over bore done.
 
Yes, ballbearian mentioned using a hole saw. I have got the impression that the pistons are a dime a dozen, an easy purchase. I suppose they are not that complicated and mostly the same, if you are boring things out, then you need a different one anyway. For now I'm stuck on getting it unstuck, I'm just stubborn. And I got it just to learn about it and tearing the pistons to shreds just doesn't seem right for that purpose. The universe has sent me this to learn patience.
 
ballbearian said:
Early circumcision can be a beneficial procedure for sure.
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Better than a late one.

So I made a 2nd cap, it worked better, I charge it up to 40lb or so pressure, but it leaks down over 5 minutes or so. I put some soapy water around it, showed it leaking thru the plastic and rubber gasket. I found a nice old gear that helps lock the cap down. I see a few little bubbles from what looks like right thru the plastic. Keeping my eyes open for a nice chunk of metal plate to replace the plastic cap with and feel safe cranking the pressure up more than 40lbs.

I did pick up the Klean Concrete phosphoric based stuff. Initially tried some full strength, but will cut it with the some water as it seems strong - a few drops on garage floor reacted fairly strong with the concrete.

I tried it without any fluid first, and now with some fluid. In both cases it held pressure well enough which tells me the pistons are plugged up pretty well, constipated in human biological terms. So I am speculating all the penetrating oil and other fluid I've tried have not worked their way down there. Maybe this phosphoric acid will have better luck. And a little air pressure could only help. I will try and find a latching air filler end that I could leave it attached to compressor.20240527_150656.jpg
 
I did find that clip-on air fill end before I went to sleep, it snapped on and amazingly worked well, output regulator showing around 40psi, had about 80lbs pressure left in the air-compressor. Was surprised in the morning it still had some pressure on it, got compressor charged up some and will check it this afternoon, give it a refresh on the Klean fluid.
 
I can be stubborn as well on a lot of things but I have to admit I would have probably have resorted to more destructive measures to the pistons by this point. We are looking forward to hearing that the pistons have moved or better yet you have got the cylinders off.
 
I am using a mix of 1/3 of the phosphoric Klean, other tap water. Just putting in a small amount, say 4 tablespoons, so it sits below the piston aluminum dome. This reacts and turns a gunky gray in less than a day, then I clean it out with some paper towel and put in fresh mix. I pressurized with the plastic cap a few nights, say at 50psi. I ordered some more schrader valves and they fit nicely into the metal oil filter removal tool. Then made a large rubber gasket from a big old truck inner tube I have saved for such things. This allows me to pressurize to full 120psi of air compressor. With acid in there. What could possibly go wrong ;) I splash some soapy water around the edges and can see some small leakage. That was seen with the plastic cap as well. With the clip on air filler I can leave it attached to the 20 gallon air compressor and let it sit pressurized overnight. I did this at the high 120psi air pressure with and without the acid mix. I don't leave the air compressor on, so in the morning it's down to say 80psi. It did not seem to leak down at a different rate without the fluid, leading me to believe these pistons are sealed up tight. We will continue the acid treatment and see if that has any luck getting to the rings. I'm thinking it is reacting with the aluminum with how quick it turns to sludge.
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Probably good you're using a full rubber gasket, wouldn't want the acid to eat the dome first.
It does look kind of sci-fi.
In search of a new element-- Constipateium !
 
I was thinking about this today and had an idea that would be filed under "brute force" that I thought I would share.

The current approach to applying force on the piston uses a static load, always pushing down. As the acid removes rust, that force should eventually overcome the strength of the rust bond and the piston will be freed.

Since the piston is not to be salvaged, my thought is to tap the piston top for a threaded rod around 3/8" in diameter. Then put a through hole in a piece of flat stock (~1/4" thick) and lay it over the cylinder, with some wood underneath to avoid marring the cylinder. Thread the rod into the tapped hole, put a nut on the top and tighten down to flat stock. If you put an electric impact on that nut, you can quickly apply and release tension on the threaded rod and, hence, the rust bond between the cylinder and piston. The rust bond is weakening from the acid bath and I wonder if you could cause it to fail under fatigue by cycling this tensile load enough times. Of course, I would remove all acid before setting it up.

Edit: I forgot to post a link to this motivational video.
 
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stl360+450 said:
Edit: I forgot to post a link to this motivational video.
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I did enjoy the motivational video! And I am open to any suggestions, wild as they may be, on getting these pistons loosened up. Now I wonder if that acid is even getting to the rusted rings. It's tight as a drum, holds air really well. One thought I had if it comes to the brute force methods, instead of circular hole saw, perhaps drill some small holes along rim of piston, intersecting with area of rings. See if the acid could seep down there better. If that failed I could just keep drilling more and bigger holes, and if I have to work my way up to the hole saw. I'll give this acid bath some more time. But my patience is not endless and I will probably give up and go brute force on it in a week or two. It would be nice if I could get the piston out at least in a somewhat whole condition, not totally destructed, just to look at it and ponder it's condition.
 
My patience has worn thin, succumbed to the inner caveman, on to plan F using unsavory means.
The other side does move and should come out, but this side I am drilling still will not budge despite removing so much material. The pieces of ring coming out do not appear rusty.
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yup, have had to incorporate that same remedy to several of my own engines. No fun!
I've graduated to a Hole Saw which speeds the process. Once the saw is working, I remove the center drill pilot (to not drill into the connecting rod) and carry on. Eventually the saw hits the wrist pin and stops but by then, the piston is break-up-able.
 
How to get to the center of the tootsie pop? Bite! I bit a little hard on that connecting rod, I should have tried to stay clear. My drill would hit those hard rings, they may be hard to avoid with a hole saw and chew those up. So I am pounding them out with a hammer and piece of oak fire wood that I did manage to split. At first I angled the engine so crank is not resting on ground. The hammer forces then are backed by the engine case top, the crank then has somewhere to travel. I came across a you tube of someone doing this and he pointed out the pistons cannot travel complete out the case, there are ledges, he broke his. So for this final piston journey I put the case up on blocks and then added some block spacers between the jugs and the case to avoid hammer into these ledges. This has been quite a sordid affair.

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Next step is to get those pins out, There are some clips I need to extract, then they should push out, right?. The drilled piston is very sticky at top at end of connecting rod, probably due to my drilling, the wiggle of the bottom connecting rod is reasonable. The other side turns nice on the top pin, but the bottom connecting rod gives a bad wobble making me thing the bearing there is bad, that could be my fault, tough to say.

Here is youtube of someone doing what I did here and breaking the ledges on the case.
He also has some on trying 3D print gaskets:
TPU:
 
kbongos said:
There are some clips I need to extract, then they should push out, right?
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Theoretically and hopefully.. Maybe @jensen or others can advise on tips for that step, assuming the pins don't just push right out.

I had a piston fail once while riding at highway speed and although the cylinder was not difficult to remove, I could not get the wrist pin out on the damaged piston. I ended up sacrificing the rod — wasn't pretty.

Congrats on separating the cylinder from the pistons!
 
Got the pins out, a small flat head inserted by the access dimple makes it easy. One pin came out without a fuss, other took a little pounding with a socket extension that was the right diameter. I was wrong about play in connecting rod, I must have been wiggling the whole crank, they both have about the same play so I think large end bearings are not horrible.
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Nice. At least those pins came out without too much damage. I guess you've reached the "now what?" phase for this motor. Rebuild? Store?

It would probably be easier to get another crank than rebuild this one. I guess this is actually a CL motor?
 
stl360+450 said:
Nice. At least those pins came out without too much damage. I guess you've reached the "now what?" phase for this motor. Rebuild? Store?

It would probably be easier to get another crank than rebuild this one. I guess this is actually a CL motor?
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It is a inexpensive CL motor, got it just to take apart and learn about them and Honda motor engine work in general, so plan is to just take apart and inspect. Don't have a bike it goes in. What I learn will hopefully help me when it matters. Maybe I'll get a 450 some day but most likely I'll just sell off useful parts, VHT here would get first dibs.
 
kbongos said:
One pin came out without a fuss, other took a little pounding with a socket extension that was the right diameter.
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I hope you didn't damage the big end of the rod by doing that. I hate to see anyone pound on a piston to get it moving, or sideways on a rod to get the wristpin out.
 
It is a shame that that piston refused to give up like it did but if you decide not to resurrect this engine or use it for a parts engine for another project please make the parts available to forum members as some are hard to find.
 
ancientdad said:
I hope you didn't damage the big end of the rod by doing that. I hate to see anyone pound on a piston to get it moving, or sideways on a rod to get the wristpin out.
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My drilling probably made that pin stick. Pressing it out with a jig would have been better. The lower connection was loose so I don't believe I was stressing that too bad. I was using the piston against the sleeve to pound against.

If the objective was to take apart and save the crank, case, and all the parts surrounding it then I don't think my approach of splitting the case was good. The case is protecting everything, I had the rollers falling out, the roller housings seem rather delicate. Hammering on any of this is probably questionable.

I think a better approach would have been leaving the case together and get the pistons loose, even if you have to cut the piston top off to get it to move. Preferably jensens method of acid and pressing could work, but may require extreme time and patience. With that method I believe you would have to press back and forth between the two pistons, as the force is going to translate only to the other piston thru the crank. A 360 degree crank would be a different arrangement.

If pistons are expendable then maybe a good hole saw is the way to go.

I took a hacksaw blade to the stone wheel and played around with trying to wedge it between piston and sleeve to try and loosen things up, but doesn't go far in, probably limited to the first ring it encounters. The lubrication or acid bath really didn't seem very effective in getting down to loosen things up.

So next step is further mechanical 'autopsy'. Try to assess why the piston was stuck so bad, what was damaged, or what have I damaged in the process. Also hopefully some time to just study how the various parts work together, I've not had any experience with these. So when you guys use these technical terms like pizza cutters I have no clue.
 
kbongos said:
Also hopefully some time to just study how the various parts work together, I've not had any experience with these. So when you guys use these technical terms like pizza cutters I have no clue.
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All you need to do to learn the given names Honda uses for the various parts is to look at the exploded views at CMSNL. We jokingly call the large detent roller "pizza cutter" only because of its appearance, of course. But as an example, "triple tree" is a term started by the chopper community, when the parts are really called top bridge and steering stem by Honda.
 
Scraping and brushing on the unmolested piston to assess. There is a hard build up of carbon. Rings seem stuck in place.
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It appears the acid bath took a pretty good bite out of the sleeve.

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Hmmm, high silicon content cast iron is impervious to 100% strength sulphuric acid, this is a strange one.

If I were to hypothesize, I think there was enough volume of iron oxides pervading (and subterranean to) the surface that the acid soak pulled the iron out of the surface and everything else with it. A pickling if you will.

That is, I don't think the acid did the damage but the pervasive rust percolating for way too long is root cause. All the acid did was be a super efficient/aggressive surface cleanser.
 
There is fresh sleeve on lower half and I could arrange a comparison test on that, do a similar acid bath and see what happens. For most of the bath I was using a mix of 1 part Klean solution to 2 parts tap water.
 
Proceeding with the phosphoric ACID experiments! Did my soak for about a weeks time in this
etch out a substantial chunk of the sleeve?

So I am putting the base of one sleeve in the phosphoric acid bath to find out. First try
left for 1 day and I have pictures showing it does react strongly. After cleanup of the crude
it shows some mild etching. Next we will try it for at least a week, do a clean and change of
fluid once a day.

First I checked my ACID product. Did I pick up the wrong stuff? Is it not phosphoric acid?
Took pictures of the container label. Tracked down the information from the vendor, the SDS
sheet. It appears to be phosphoric acid, good.

Klean-Strip® Concrete & Metal Prep does the job of three products: (1) Removes rust from iron and steel surfaces,
(2) treats metal surfaces, including galvanized and aluminum, to allow better paint adhesion, and (3) etches concrete
to allow paint or stains to penetrate and adhere.

Product Code: GKPA30220
CAS # Hazardous Components (Chemical Name)
3. COMPOSITION/INFORMATION ON INGREDIENTS
Concentration
Phosphoric acid {Orthophosphoric acid} 7664-38-2 10.0 -30.0 %
Isopropyl alcohol {sec-Propyl alcohol; IPA;
2-Propanol}
67-63-0 0.1 -1.0 %
Alcohols, C9-11, ethoxylated 68439-46-3 0.1 -1.0 %
Additional Chemical: Specific percentage of composition is being withheld as a trade secret Information

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Here's after washing it off in the kitchen sink:

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I am also looking at the piston that did come out without drilling. I've cleaned up around the rings with just some mechanical brushing and scraping. Those things are wedged and stuck in there, really good and tight. I'm trying some razor blade cleaning around the split in the piston, try wedging sharp pointy objects into tiny split in ring to try and get movement. Rings refuse to move or budge. The only other experience I have with rings is the one time I took the top end apart on my CM400. I pulled of a ring or two just to inspect and clean. They came off without too much effort, maybe I little gummed up with age, but not bad. This feels like I am an archeologist working on 1000 year old bones. No, I'm not trying to save these, just trying to understand what happened to them.
 
So the experiment is showing the Klean phosphoric acid product does eat up the sleeve. After 1 day with plastic and rubber band I found a round plaster container that snugged up into the sleeve. Another 5 days with about a 1/4 inch of fluid, changing about once a day, after a day it turns into a sludge especially around the metal, showing a strong reaction.
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Another ongoing experiment trying to loosen the rings on the piston that came out clean. A few days in a cocktail bath of kerosene, tranny fluid, a touch of brake fluid and a few squirts of penetrating oil. They are stuck in there really good, seems like a combination of carbon build up, oxidation, rust.

And then a third experiment where I put the mangled drilled out piston top into a plastic container with some muriatic acid, wow, that just took off! Had to rush open the garage door, place it outside, it was heating up hot in seconds, nasty fumes. It was all over in like 5 minutes.
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