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Crankshaft Cleaning

Even extra witness/scribe marks is good in case any get obliterated somehow. Crank sprocket positioning does seem crucial, especially since we don't have ultra expensive adjustable cam sprockets. I've heard Capellini does make one, but may be for 350's, never seen it. This is very interesting.
 
I had a little time last night for the first press on the fixture I had made. It went really well and actually pressed out much easier than I expected.
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Once the outer flywheel was removed I went ahead and scribed a line across the end of the center main bearing journal for reference to the inner flywheel face. I’ll do the same with the other side. I am still curious what method Jensen, G-man, or anyone else with experience uses to document the relationship of the center shaft to the two inner flywheels?
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The other side pressed out easily as well, maybe needing a bit more force but it still went smoothly.
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Tonight I hope to get time to work on the center section which I believe is usually a little more stubborn coming apart. I hope it goes as smoothly as the outer flywheels did 🤞
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Looks really good so far. The crankpins look splined, but it's hard to imagine them actually creating a position-reference.
 
Looks really good so far. The crankpins look splined, but it's hard to imagine them actually creating a position-reference.
Without cleaning anything up yet, it appears to me the shaft was splined but the bore of the flywheel was not. If that’s the case then very little reference. I’ll do a little cleaning to confirm this.
 
More of a straight knurl than a spline. Must be for the interference fit aspect. The first pic of G-man's doesn't show them on his crank.
There is a right and left side to the rods, so that the small end hole is in it's correct position.
 
More of a straight knurl than a spline. Must be for the interference fit aspect. The first pic of G-man's doesn't show them on his crank.
There is a right and left side to the rods, so that the small end hole is in it's correct position.
Agreed on your terminology ballbearian. I admit some of the terms I use in this exercise may not be technically correct given that I’m just a guy in his shop as opposed to a trained professional.
The first photo G-man posted is of a K0 450 crank. This one I am working with came from a K7 450, although oddly, it does have K5 on the side of the rods. That casting feature may be meaningless in regards to our current use of K descriptions for Honda models however.
 
Agreed on your terminology ballbearian. I admit some of the terms I use in this exercise may not be technically correct given that I’m just a guy in his shop as opposed to a trained professional.
The first photo G-man posted is of a K0 450 crank. This one I am working with came from a K7 450, although oddly, it does have K5 on the side of the rods. That casting feature may be meaningless in regards to our current use of K descriptions for Honda models however.
I just like saying the word 'knurl', it rhymes with gnarl. :geek:
G-man's crank rod pins look copper plated, instead of knurled.
Most of my damage has been the small end bores, so I notice the oil splash holes.
 
Not to detract from the awesome teardown posts…

I’m trying a twist on jensons pump setup.

I had removed the big end plug.

Used a soft rubber plug on the trap side, and fitted a hose on the plug side. Then have the pump suck the solvent down through the big end.

It’s working. I had been blowing air down through the big end. Which works. But a little more came out using this technique.
 
No worries about detracting, this is all part of the fun Teebo!
So it sounds as if you have the crank submerged in a solvent solution? Did you use acetone?
Post some pics of your setup. Enquiring minds want to know. 😀
 
Difficult to get a pic of the rubber plug. It was slightly larger than that main channel, so a tad over 7mm.

I tired forever to get it in from the trap side. Failed. So I pushed it all the way through from the other side.

At the moment this is in diesel. Been a hellacious week at work and didn’t get a chance to switch to acetone. I need to find a smaller container. In this pic that would be around $90 in acetone. Though I supposed i could filter it and use for cleaning in the future. I use acetone a lot.

The pump is a 3.7 gpm fuel pump off Amazon.

I let the pump run until it starts to get too warm. I do think drawing solvent through those tight tolerances and passages makes it work harder. IMG_1211.jpeg
 
About switching to acetone. I wouldn’t expect plastic to fair well. So a stainless or metal container. Not convinced at all the hoses would do well either.
 
Based on my recent experience, make sure you put some engine oil into the big end bearing soon after you do any finish cleaning with solvent afterward in order to avoid dampness starting rust inside the big end.
 
Based on my recent experience, make sure you put some engine oil into the big end bearing soon after you do any finish cleaning with solvent afterward in order to avoid dampness starting rust inside the big end.
Ya. I was going to flush some oil through everything after I’m done with the solvents. Probably wipe it lightly all over.

I’ll take it to the machinist to press new plugs.
 
I like your idea and setup Teebo. I also like the use of diesel. Personally I would feel better sticking with it as opposed to acetone. Less expensive and less volatile.
I guess every time you stop to let the pump cool you also rotate the connecting rods some? Do you move them when it’s actually pumping to help agitate the debris?
 
I like your idea and setup Teebo. I also like the use of diesel. Personally I would feel better sticking with it as opposed to acetone. Less expensive and less volatile.
I guess every time you stop to let the pump cool you also rotate the connecting rods some? Do you move them when it’s actually pumping to help agitate the debris?
Yes! I should have mentioned that. I do periodically move the conrod to different positions. Sometime I’ll sit there and rock it back and forth. Sometime lift up slightly to allow whatever tiny clearance there is right above the oil passages.
 
I should also add… my neighbors probably feel like they live next to a truck stop. Let’s just say one should make extra sure all hoses are properly fitted and secured.
 
On my side of things, I did manage to press apart the remaining center section of this 450 crank. Like the previous time it came apart smoother and easier than I had imagined it might. I am happy to take the win.
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To be expected there is plenty of crud in the centrifugal trap. The bike this crank came from was a K7 CB450 that had a seized cam roller that the cam chain had eaten almost in half. It was gruesome find in a running bike! The amount of debris from this is another reason I had previously left this crank for dead.
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Lots of crud built up in the oil passage leading to the connecting rod bearing. The exact thing that Teebo is flushing with his pump system albeit his crank is not in as bad as shape as this one.
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Once apart I went ahead and drilled out the plugs in the connecting rod journal. The debris you see below is not from drilling. All of this came out with one brief shot of air after I had drilled the plug. There is still more crud within the passageway. Needless to say this not what is wanted in the pathway to the bearing.
The one comforting observation I have made is even with all of this debris in the centrifugal trap and passageway, the bearings for the connecting rods were still remarkably clean and still rolled smoothly before disassembly. Maybe Honda really knew what they doing in designing this system? Given this observation it makes sense that a bike that has been well cared for over its life with no cam, roller, or chain issues should have a crank that is still in reasonable working order. I wonder if in some cases of a clean motor it is better to leave the centrifugal trap undisturbed instead of stirring up settled debris?
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More of a straight knurl than a spline. Must be for the interference fit aspect.
Yes, after a little cleanup it is easy to see this is indeed knurling and contrary to what I thought it is done not only on the shafts but also in the bores. It does not seem pronounced enough to rely on it for any reliable indexing purpose and I am glad I made the scribe marks on the end of the center shaft now. In fact I wish now I had made similar marks on the ends of the crank journal shafts as well but those are not as critical since they will ultimately find their alignment based on the dial indicator.
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The one comforting observation I have made is even with all of this debris in the centrifugal trap and passageway, the bearings for the connecting rods were still remarkably clean and still rolled smoothly before disassembly.
It's amazing that enough oil reached the mains considering the amount of crud in the passage way.
 
It's amazing that enough oil reached the mains considering the amount of crud in the passage way.
Exactly! Even though I bought this as a running bike it wasn’t really being currently ridden. If I remember correctly it had somewhere around 20K miles on the odometer. I never ran for more than a few short minutes myself because I discovered the cam roller problem when doing a simple initial tuneup. It is possible that I caught it right before the inevitable destruction commenced.
 
So many of these bikes have a broken history of sitting (some in a poor environment) then being 'revived', sort of, then sitting again before we get them. My last couple were victims of a poor, or incomplete revival and bear the damages you would think that resulted; piston/ring, wrist pin/ small end and even crank bearing journal damage. Low miles or signs of fairly recent work, don't mean a thing when underlying issues from contamination or blockage haven't been fixed and the bike was then used again in that state until it acted up again and got sidelined.
My experiences (few that they are) say that it's less common to find a higher mileage but well maintained motor in much better shape.
The land of barns full of old bike treasures keeps coughing them up with tales of neglect. People who pull them out, hose them off, put gas in it and start them saying, "Well, it's a Honda, after all", with a grin, have no clue what they are actually doing. It would have been better off left sitting in the barn instead of being worked on halfway.
 
So many of these bikes have a broken history of sitting (some in a poor environment) then being 'revived', sort of, then sitting again before we get them. My last couple were victims of a poor, or incomplete revival and bear the damages you would think that resulted; piston/ring, wrist pin/ small end and even crank bearing journal damage. Low miles or signs of fairly recent work, don't mean a thing when underlying issues from contamination or blockage haven't been fixed and the bike was then used again in that state until it acted up again and got sidelined.
My experiences (few that they are) say that it's less common to find a higher mileage but well maintained motor in much better shape.
The land of barns full of old bike treasures keeps coughing them up with tales of neglect. People who pull them out, hose them off, put gas in it and start them saying, "Well, it's a Honda, after all", with a grin, have no clue what they are actually doing. It would have been better off left sitting in the barn instead of being worked on halfway.
Very valid points, and stated very well. I agree with you Tom.
 
Yes, after a little cleanup it is easy to see this is indeed knurling and contrary to what I thought it is done not only on the shafts but also in the bores. It does not seem pronounced enough to rely on it for any reliable indexing purpose and I am glad I made the scribe marks on the end of the center shaft now. In fact I wish now I had made similar marks on the ends of the crank journal shafts as well but those are not as critical since they will ultimately find their alignment based on the dial indicator.
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This is such a cool photo.
 
People who pull them out, hose them off, put gas in it and start them saying, "Well, it's a Honda, after all", with a grin, have no clue what they are actually doing. It would have been better off left sitting in the barn instead of being worked on halfway.
Yes, as in those ridiculous YT videos all titled "will it run?". Of course it will run if you work on it long enough, but the real question should be "how long will it run?" given a minimal, quickie re-awakening.
 
I am enjoying this thread a lot, a big thanks to all who share their expertise here. I have very limited experience, but I am learning stuff! Questions appear in my pea sized brain, like I thought cranks were just big chunks of metal? These things are pressed together? Apparently some are, some not. Do they really have oil passages drilled into them? Apparently, oil needs to be delivered to the joints. Needle bearings? I thought they used bolt on sleeves. Apparently there are lots of design choices. How much does a 20ton press cost? Apparently I can buy one from HF for less than $200. Of course the real issue is do you have room for it. I could put it in the back yard and put a tarp over it ;) I pressed in and out a ball joint in a vehicle lately, that was a new experience. Used a rental tool for this, really just a big c-clamp with some fittings. That was after learning that lower control arm bushings are hell on earth to remove, so off to plan-B, leave them on and replace ball joint only. I replaced the struts too where my thumbnail got whacked and I now have a better appreciation of physics and spring tension.
 
I am enjoying this thread a lot, a big thanks to all who share their expertise here. I have very limited experience, but I am learning stuff! Questions appear in my pea sized brain, like I thought cranks were just big chunks of metal? These things are pressed together? Apparently some are, some not. Do they really have oil passages drilled into them? Apparently, oil needs to be delivered to the joints. Needle bearings? I thought they used bolt on sleeves.
All the earlier twins used ball and/or roller bearing crankshafts with full-circle big end rods, seemingly non-serviceable to the average person because of the tools and methods required to take them apart and replace parts as needed. Honda began more commonly using plain bearing crankshafts with bolt-together, replaceable rods and insert bearings when the CB750 was released, and that design crankshaft was used in later models.
 
An outer wheel from any 5-speed crank should work there. Tricky to sleeve because of the cur clip groove.
 
My apologies that I haven't been keeping up with all of the comments but this is my 'horse-shoe' that I use for pulling cranks apart. I widened the bed on my press so that cranks up to 450 would sit between the two beams.003 Pressing out big end.JPG
 
For anyone who is worried about pulling these things completely apart, putting them back together is easier than you think because there are no explosive releases of force as they go back together.

Most of the crank centre-sections are pressed up tight. i.e. no measurements to make or adjust.

Two things matter:

1) the alignment of the timing sprocket. Usually, a tooth peak or valley is lined up with TDC on the alternator side, so you need to note which yours is...

2) the two crankpins need to be at 180 degrees to eachother. Try and get it as close as possible and it can be tweaked in the press resting the crankpins on two sturdy parallels and then pushing down on both wheels with a bar across the top.

When pushing on the outer flywheels, the side clearance at the big end should be 3-9 thou, I think. There is plenty of axial float in the bearings so the 'finished length' of the crank is not critical.

I do the truing up in my press and only use my copper hammer to finesse the last thou. Put preload on in the press then tap the frame.

My alignment fixture is just a set of crankcases.aligning in press MG_8853.jpgdial gauge IMG_9080.jpg
 
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Here is another 'horse shoe'I made to pull apart NSR400 cranks.


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The NSR400 is quite a challenge to assemble and true-up. I made my own roller-fixture to bolt to my miller bed.

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This is my alignment fixture for the CB72/77 centre section. It hold the two crank pins at 180 or 360 degrees, plus there is an index pin to locate the cam sprocket in the correct orientation.002 press fixture.jpg
 
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An outer wheel from any 5-speed crank should work there. Tricky to sleeve because of the cur clip groove.
Thanks Graham for checking back in on this thread and confirming this information on swapping an outer flywheel. Also I appreciate you restating the important measurements to note on reassembly of a 450 crank. Once I get the experimental crank I pressed apart cleaned up, I’ll be ready to try the reassembly and will probably need some clarification from you on some points as I go along.
Please continue to check in on the forum and post pictures of the fascinating work you do on these old Hondas.
 
This is a super helpful thread and timely as I am now down to the crank on my cb72. Trying to figure out where to go with it as well. I really have no tools etc to press it apart, but do have a question. This plug everyone is talking about - would a good approach be to drill that plug out (reference pic below - assuming this is the right plug as I understand it) soak in gasoline/diesel/acetone or solvent of choice? Not trying to hijack a great thread, just making sure I understand before I attempt anything.
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Yes, I drill and tap the plug M6, then use an M6 Bolt and socket to pull it out. You can run a drill in there to pull most of the crud out.

Be aware though that the centrifuge at the back of the flywheel get clogged also and needs cleaning. There are also tiny holes in the main nearing which must be cleaned.

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There is the other thing I cant seem to visualize in this thread - ‘centrifuge at the back of the flywheel’ - what exactly am I looking for?
 
You can see into the centrifuge by pulling the inner main bearings away from the flywheel. Oil squirts into the centrifuge via the tiny holes in the main bearings and then gets flung up to the big end by centrifugal force.
 
That is a great pic of what you can't see with the crank assembled but what can get clogged and even more so, the bottom pic of Chris's post #119 of the big end bearing pin oilways.
Those little holes in the main bearing can get clogged with debris. Also, the centrifuge filled up with sludge (just like the oil filter) over time and stops being a centrifuge. The oil just spills out before it gets to the big end.
 
Hi all, is there anyone on this thread who has pressed apart a 450 DOHC crank that may have an old rod lying around? I would like to know the ID of the big end and the centre to centre measurements, in MM or In, doesn't matter. Thank you.
 
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