Author Topic: rosewood's cb550F restomod - swing arm dilemma, frame damage & custom bushes  (Read 906 times)

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Offline rosewood

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Well thought I would finally share my project bike with the group...I picked this up off a friends brother sight unseen after I was told it was a running bike...Had it transported from Wellington to Auckland, NZ about ten years. It looked complete and came with some parts he had collected and intended it to be a cafe build. I had some friends who had been building cafe's back then that got me interested so I took the plunge not knowing much about bikes OR what I was getting myself into at the time. I had only ridden a handful of times many years ago..

I have access to a full machine shop including CNC's at work and enjoy a project having previously been into modifying Honda cars of the late 80's early 90's era I thought why not having always wanting to do something like this. I knew nothing about these machines.

This site has been a huge resource from back then and a special thanks to Mark aka Hondaman who has been a wealth of knowledge over the years behind the scenes with all my pm's.

I thought this would be a 1-2 year project, but having children and all that life throws at you along the way it is close but still not complete! I have a hoard of images and thought its time to share the journey and hoping it will also help motivate myself get the last of it done!

I plan to just post a a few pics now and then, feel free to comment but go easy as I was young and stupid back then....10 years on maybe a little wiser but probably not lol..

The bike as it arrived... 8)   This had 80k km's on the clock a long list of owners over the years and had sat for over 15 years when I received it. This should have been tell tale sign if I knew better back then....It has been the bike that has kept on giving every step of the way..
« Last Edit: October 23, 2025, 12:35:40 PM by rosewood »

Offline rosewood

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Re: rosewood's cb550F restomod
« Reply #1 on: October 17, 2025, 06:00:13 PM »
It came with a Haynes manual, mini gauges, 3ohm dyna coils, k&n pod filters, keyster carb rebuild kits, some smaller aftermarket indicator lights and probably some other misc bits and pieces I've forgotten about..

A closer look reveled a lot of damage which seemed cosmetic at the time, gauge clusters bashed, front and rear fenders dented, headlight cracked, rusted out seat pan, rotten header and exhaust, worn fork stanchions etc etc. The PO had already fitted the coils, and rebuilt the carb with the keyster kits.

An old neighbor into his Harleys and previously owned GB honda's back in his younger days offered to come have a look and we put some fuel in the tank and surprisingly it fired up after a few attempts...

Not sounding too healthy there was a smoke everywhere, fuel pissing out of the carb but he was brave enough to take it up the road...it ran and he came back after 200m and said..."it seems like a good starting point"..

I immediately started digging into it a bit further and came across this site...I went through the carbs and found a fuel valve upside down, a missing main jet holder. I fashioned a replacement out of some steel and had a friend patch the header ready for its second attempt..

Much of the same and after some researching I realized my points plate needed replacement as well as the plug caps and the coils were the wrong ones. Some communication with HM and after a few weeks I had a new points plate, plug caps and a resistor pack for the coils...he suggested I fit one pod filter in the standard box which I managed to knock up in the workshop..

Much the same result however with fouled plugs...I pushed forward starting to clean up some other parts of the bike while digging further and further into this site researching as much as I could..

Offline denward17

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Re: rosewood's cb550F restomod
« Reply #2 on: October 17, 2025, 06:23:27 PM »
Following for progress......good bones to start with it looks like.


I like the way you improvised on the air filter inside the air box.

Offline rosewood

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Re: rosewood's cb550F restomod
« Reply #3 on: October 17, 2025, 06:31:17 PM »
I proceeded to continue with gathering parts and making a top triple clamp to mount the mini gauges and some fork clamps for the front headlight. front brake came apart and I machined a new piston from some stainless on the lathe..

I started to read about primary chain wear and the bike having done 80k km I realized it was probably time to drain the oil and drop the pan...sure enough oil was black and thick as anything, also found some bits of plastic in there from who knows where. I peak inside and sure enough the bottom case had some serious primary chain wear, cam chain tensioner was not assembled correctly.

At this point I was starting to question my life choices thinking I had purchased a running bike...I knew the engine had to come apart and I would be in over my head..

Offline rosewood

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Re: rosewood's cb550F restomod
« Reply #4 on: October 17, 2025, 06:38:44 PM »
Following for progress......good bones to start with it looks like.


I like the way you improvised on the air filter inside the air box.

Thanks but keep following it gets progressively worse  :)

Offline rosewood

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Re: rosewood's cb550F restomod
« Reply #5 on: October 17, 2025, 06:49:18 PM »
Finally finding the courage I removed the tappet cover, head and cylinders which ultimately revealed broken piston rings on two maybe 3 pistons from memory..first time digging this deep into an engine it was a bit overwhelming but I systematically starting dismantling everything...not having a valve spring compressor but a large clamp I've had sitting for years I turned up some bits on the lathe and mill i got the head and the top end apart..
« Last Edit: October 17, 2025, 06:51:18 PM by rosewood »

Offline rosewood

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Re: rosewood's cb550F restomod
« Reply #6 on: October 18, 2025, 12:39:38 AM »
I continued pulling the bottom end apart and to my surprise everything seemed to be in tact down there with no major surprises so far..I bagged and tagged everything while starting to clean up parts and cases here and there and purchasing parts...plasti-gauge showed my bearings were all toast I cant quite remember but after some lengthy messages with Hondaman we determined what bearings to buy from CMNSL with what they had still available, we worked out I could get just within spec on most journals with the exception on one or 2 which were just outside the limit but was advised running slightly thicker oil once everything was run it would still be ok.

It was at about this time I decided to stop recording what this project was costing me....

Offline rosewood

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Re: rosewood's cb550F restomod
« Reply #7 on: October 18, 2025, 03:18:31 AM »
More parts started arriving and got the bottom end back together relatively trouble free...I cleaned up the head and lapped the valves, they were on the limit as well but that's all I had to work with so I just proceeded to put it back together, I think I also did a quick port match of the head with the intake runners..

I measured the cylinder bores and like everything they were on the limit of wear. Not wanting to take the plunge on reboring incase this project was a complete failure I opted just to to re-ring with a cruzin image ring kit. I figured if everything did pan out I could always do the top end again in the frame with oversize pistons then. I had the cylinders deglazed/honed at the local bike shop. In hindsight I should have just opened the wallet and gone the proper route reboring with over size pistons at this stage.

The cruzin image ring kit proved to be an issue when I finally got around to checking the end gap...one kit in particular was gapped way too big, when I contacted the seller on ebay I was immediately blocked...this proved to be a headache and I resorted to finding original honda ring kits from a couple of different ebay sellers from the UK and the Canada..

Offline Stev-o

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Re: rosewood's cb550F restomod
« Reply #8 on: October 20, 2025, 07:45:09 AM »
Nice project...
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline rosewood

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #9 on: October 20, 2025, 12:21:23 PM »
I had a stroke of luck with a parts haul locally. NZ is very small market for these bikes and there was a listing for a 550F project bike come up, it had a pile of parts pictured with it and I managed to contact the seller who was kind enough to let me have a look and take a few things for a reasonable price. Most parts looked like they had sat in a muddy puddle for the best part of 10 years but for me they were like finding gold. Not knowing the condition of anything I still figured they were worth taking. I managed a score a set of 069A carbs, an almost complete head, a damaged tappet cover with (pinned shaft version) complete with tappets, camshaft, alternator cover (my original was sporting some road rash) and a few other bits.

With the bottom end complete, I continued cleaning up some remaining parts, polishing, ultrasonic cleaning the carbs etc. I was finally able to mock up the engine. I painted the jugs black and was happy with how everything was looking. It was quite a milestone finally seeing the engine like this..

I laser cut some acrylic to make a stand to sit the carbs on, this came in handy to hold them while working if not just looking cool displaying them on the work bench...

Offline BenelliSEI

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #10 on: October 21, 2025, 05:43:47 AM »
Fascinating and following. I do most of my stuff with a hack saw and a selection of files! Nice to see how it’s done properly…….

Offline Stev-o

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #11 on: October 21, 2025, 07:00:56 AM »
Your motor looks amazing!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline MauiK3

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #12 on: October 21, 2025, 07:45:39 AM »
Acrylic stand for carbs? Showing off!! Very nice looking stuff. Nice project and looks like you are having fun.
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Offline rosewood

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #13 on: October 21, 2025, 12:12:18 PM »
Thanks Guy! I wouldn't say I'm doing things properly, just lucky I have access to some cool equipment at my work. First time also doing something like this..it was and still is a learning curve..

Offline rosewood

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #14 on: October 21, 2025, 12:50:07 PM »
With the top end still to be put back together I knew I still had some issues. This motor had high miles and I would say poorly maintained, when I cleaned up the head and lapped the valves some valve seat widths were right on the min limit if not over, I also had some significant wear on the valve guides, I didn't measure but there was some play, at the time I just wanted to get it all back together and see if it would run ok. In hindsight I would have done things differently.

I cleaned up the spare head I picked up, and although it was rough it actually looked ok, valve play was significantly less and I had more to work with the seats, the mating surface was in bad shape and with the help of a machinist at work we skimmed it using a boring bar as a fly cutter. It wasn't perfect and I didn't want to take too much off but felt it was good enough. I was still missing a spring and maybe the the retainer/ keepers, from memory I may have found some of those parts locally but I think I also had to use some from my original head. The head went back together and I was more confident on using this one compared to my original.

My tappet cover was the other issue, it was the two piece design with worn out outer holes. I posted about this at the time which ill link here:

http://forums.sohc4.net/index.php/topic,162029.0.html

In short I used some ejector pins for tool making to replace the worn two piece design with one piece. Not a perfect solution but I plan on revisiting this in the future and address the potential play/support in the worn hole with some type of shimming or even bushing the cover.

I also had more parts turning up...I finally had everything ready to put the top end back together..


« Last Edit: October 21, 2025, 12:53:24 PM by rosewood »

Offline rosewood

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Re: rosewood's cb550F restomod - rebuilding head and tappet cover remedies
« Reply #15 on: October 21, 2025, 05:12:06 PM »
Finally the time came to put the top end back together....I had sourced some original OEM honda rings for the pistons. After measuring the gaps on these I still had some issues and had to resort to using the oil control rings from my cruzin image ring kit not ideal but I had run out of options. The top end went back together relatively straight forward also considering the was all new to me. My mother was in town for a wedding and while wrestling with the cam shaft sprocket late at night she walked in and leant a hand while a was juggling a few things. Gave me an opportunity for a cool photo!

I remember while installing the clutch basket there was a bit more play than the spec allowed, I just happened to have some shim stock in my tool box that had been there for 10years I was able to make an additional shim...It all worked out and the engine was finally back together, this may look fast but the engine alone was about a years work to get to this stage.

It was a great feeling seeing the engine completely finished on the bench I was more than happy with how it looked, a lot of time wen into cleaning, blasting and polishing parts and I felt like it was all worth the effort.

I had also started making up some parts to complete the exhaust with my new muffler but more on this later..

 

Offline denward17

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Awesome progress!

And, way to go Mom!

Offline HondaMan

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Wow, you even gets the chicks to come and help you? Now, THAT's a build! :D
Did you have to make that copper head gasket? I might be concerned about oil weepage at the 2 oil ports on the outboard ends of the cylinders: see if you can get thicker O-rings for those holes so the O-ring stands 0.2mm or more above the surface, lest it weep all over your handiwork. :(

You have access to some of the coolest tools! I am slowly becoming jealous... ;)
See SOHC4shop.com for info about the gadgets I make for these bikes.

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Offline rosewood

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Wow, you even gets the chicks to come and help you? Now, THAT's a build! :D
Did you have to make that copper head gasket? I might be concerned about oil weepage at the 2 oil ports on the outboard ends of the cylinders: see if you can get thicker O-rings for those holes so the O-ring stands 0.2mm or more above the surface, lest it weep all over your handiwork. :(

You have access to some of the coolest tools! I am slowly becoming jealous... ;)

Thanks Mark! That is not a copper gasket I think I used VHT copper gasket cement (spray can) on the gasket from the Vesrah kit. I can't quite remember now but I do recall learning about the potential weep here and I think I did pay attention in this area with the right o rings if they were required. The engine has since been run but time will tell if this will become an issue...

Watch this space! there are more cool tools/machinery that get involved..
« Last Edit: October 21, 2025, 08:47:13 PM by rosewood »

Offline scottly

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #19 on: October 21, 2025, 08:47:56 PM »

My tappet cover was the other issue, it was the two piece design with worn out outer holes.

In short I used some ejector pins for tool making to replace the worn two piece design with one piece. Not a perfect solution but I plan on revisiting this in the future and address the potential play/support in the worn hole with some type of shimming or even bushing the cover.

There have been discussions about threading in set-screws or such into the cover directly over the shafts, pushing them down. All the wear occurs at the top of the bores. The question was if there was enough material to support the threads, which was never really answered. If the cover is too thin, perhaps thicker pieces could be welded to the cover, similar to the cam support modification done to the 750s.
Cool pic of your mom; mine has helped me with some of my projects over the years, too. 8) 8)
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Offline rosewood

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Re: rosewood's cb550F restomod - parts haul and engine mock up
« Reply #20 on: October 22, 2025, 12:15:17 PM »

My tappet cover was the other issue, it was the two piece design with worn out outer holes.

In short I used some ejector pins for tool making to replace the worn two piece design with one piece. Not a perfect solution but I plan on revisiting this in the future and address the potential play/support in the worn hole with some type of shimming or even bushing the cover.

There have been discussions about threading in set-screws or such into the cover directly over the shafts, pushing them down. All the wear occurs at the top of the bores. The question was if there was enough material to support the threads, which was never really answered. If the cover is too thin, perhaps thicker pieces could be welded to the cover, similar to the cam support modification done to the 750s.
Cool pic of your mom; mine has helped me with some of my projects over the years, too. 8) 8)

With a 5 axis CNC I'm certain the outer holes can be machined and bushed quite easily, I will explore this when I get a chance. If anyone is willing to send me a scrap cover id be happy to give it a go sooner...

Offline rosewood

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With the engine work complete for now it was time to focus on other parts of the bike....I completely stripped the frame. I had found that the swing arm bolt was stuck, I had been soaking this in PB blaster and pounding on it for weeks and nothing I tried seemed to work. I had figured the bolt was seized to the collar some, probably rusted. Embarrassingly I had an idea to press it out on a hydraulic press, a decision I came to regret. At first I thought the bolt was moving but I soon realized I had moved the whole collar and bolt assembly together which resulted in some serious damage to the frame. My last resort was to cut the bolt between the frame and swingarm with a reciprocating saw.

There was some repair work to do and I turned up a mandrel to help repair the frame, a colleague with more experience in this area helped and we heated the frame and with the help of the mandrel we managed to get the inside area of the frame back into position, I still had to patch the torn section on the out side but more on this later..

My swingarm collar was severely worn and after some research I found that collars for the CB550F were no longer available, I had already purchased some replacement brass bushings from an ebay supplier. After some messages with Hondaman I learnt that using these bushes were not ideal and it also depended on the collar, there were variations on all collars over years and obtaining the optimal fit to address swingarm play would be a challenge. The very reason why Hondaman offers a custom swingarm rebuilding service. Being in NZ this was not an option and after some more research I opted for a NOS 750 collar, I sourced some PB1 phosphor bronze and with the help of another colleague at work we used a CNC lathe to turn up some custom bushes. We were able to measure the bush diameters while still on the lathe and keep tweaking the cuts. This resulted in an absolute perfect fit to match the collar! Another piece of this puzzle solved and I was confident I would have next to zero play in the swingarm. 
 
« Last Edit: October 28, 2025, 01:01:59 PM by rosewood »

Offline BenelliSEI

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Fabulous. Really enjoying this one! Thanks for sharing.

Offline HondaMan

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That's a tough recovery for the swingarm!
You have a good start with the early collar instead of the late one (which seized in your frame, like many of those bugges do...), but you must alos drill grease passages into whatever bolt you use, unless you can obtain an early bolt with the grease zerks on the ends: those already have the greasing passages in place. The collar you have greases from the inside-out, via the passages in the center of the early-style bolts, from (JIS) fittings out on the ends of the bolt. The inside of the collar has a recessed zone underneath its greasing passages: those are where the swingrm's bolt must deliver the grease, then through those holes, through the holes in the collar, into the center of the bushings. The clearance should not be more than 0.0010" between the bushings and the collar, too. I rebuild them a lot...

If you have one of my books, this whole setup is detailed in the Frame section of them.
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: https://sohc4shop.com/  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline rosewood

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That's a tough recovery for the swingarm!
You have a good start with the early collar instead of the late one (which seized in your frame, like many of those bugges do...), but you must alos drill grease passages into whatever bolt you use, unless you can obtain an early bolt with the grease zerks on the ends: those already have the greasing passages in place. The collar you have greases from the inside-out, via the passages in the center of the early-style bolts, from (JIS) fittings out on the ends of the bolt. The inside of the collar has a recessed zone underneath its greasing passages: those are where the swingrm's bolt must deliver the grease, then through those holes, through the holes in the collar, into the center of the bushings. The clearance should not be more than 0.0010" between the bushings and the collar, too. I rebuild them a lot...

If you have one of my books, this whole setup is detailed in the Frame section of them.

Thanks for the input Mark, you probably don't remember but we discussed this at the time, the new bolt I have has been drilled and has the zerk fittings etc..I'm not sure if I documented it at the time there may be some pictures ill show later if I come across them.

Here's a sneak peek after assembly....you can see the modded bolt.. :)
« Last Edit: October 27, 2025, 01:04:38 PM by rosewood »