Topic: rosewood's cb550F restomod - swing arm dilemma, frame damage & custom bushes

[rosewood]

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...    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..

[rosewood]

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..

[denward17]

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.

[rosewood]

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..

[rosewood]

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 

[rosewood]

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..

[rosewood]

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....

[rosewood]

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..

[Stev-o]

Nice project...

[rosewood]

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...

[BenelliSEI]

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…….

[Stev-o]

Your motor looks amazing!

[MauiK3]

Acrylic stand for carbs? Showing off!! Very nice looking stuff. Nice project and looks like you are having fun.

[rosewood]

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..

[rosewood]

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..

[rosewood]

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..

 

[denward17]

Awesome progress!

And, way to go Mom!

[HondaMan]

Wow, you even gets the chicks to come and help you? Now, THAT's a build!
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...

[rosewood]

Wow, you even gets the chicks to come and help you? Now, THAT's a build!
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..

[scottly]

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.

[rosewood]

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.

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...

[rosewood]

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. 
 

[BenelliSEI]

Fabulous. Really enjoying this one! Thanks for sharing.

[HondaMan]

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.

[rosewood]

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..

[HondaMan]

Rats...something's happened to our picture viewer? I can't see pix.

[MauiK3]

For some reason I'm not able to make the jpg's come through.
Nice project

[rosewood]

Rats...something's happened to our picture viewer? I can't see pix.

Any idea what's up with the picture viewer? Is this just a temporary thing or will it get sorted? I know I've added alot, maybe too many?

I've added the last picture again to see if it works....have plenty more to share with this project but would be a shame if I cant post any images..

[denward17]

picture issues:

http://forums.sohc4.net/index.php/topic,206017.0.html

[HondaMan]

Pix are back!
3 cheers for the webmasters here!

[rosewood]

Pix are back!
3 cheers for the webmasters here!

Not so sure Mark....I'll go through and reload my images on this thread when I get a chance...

Just checking some notes and wanted to correct a couple of things I've mentioned. I used phosphor bronze (PB1) for the swing arm bushes not LG2 bronze. I think i may have purchased a new swingarm bolt with the grease holes already drilled and not drill these myself...

[rosewood]

With the frame temporarily repaired for now I started working on other areas of the bike...Not wanting to rebuild my wheels completely and respoke I decided to mask the rims and  bead blast the inner hubs to clean them up, the spokes also had surface rust so these got a clean up in the process. I removed the tyres to find the rims rusted inside, this was cleaned up with wire brush on a drill. I had the wheels trued by an old local that did this as a side business...painted the inner surface with a rust converter to help protect, replaced the bearings and had them wrapped in new Avon's. Another job off the list.

Attention then went back to the frame, with the damage around the swingarm I wanted to check frame frame geometry a bit closer, I built a jig to sit the frame on, I figured this may also come in useful during the assembly. With the engine back in the spine looked good but a closer look at the swingarm showed something was off...The sprockets weren't aligned and after some head scratching I concluded that my swingarm must have been bent. I sourced a replacement on ebay and once that arrived and assembled sure enough the sprockets aligned perfectly. I could then look at the front a bit closer, using stringlines the best I could I found the front wheel was not aligned to the back, I turned up some cone fittings to check the steering head/stem and sure enough this showed it was bent/twisted. The bikes original front guard had seen some damage as well as the headers consistent with a crash/hit from the front....Great!!

[HondaMan]

That's a sad bunch of damage, but I might mention this: in 1972 (when my 750K2 was but 9 months in my hands) I was hit from behind on the right-side exhaust pipes by a Suzuki GT750 waterbike rider going nearly 50 MPH: I had just [been] stopped to avoid hitting the train (which he did). This pushed the right side of the frame forward about 1/4" (also bending the engine mount bolts and aiming the 2 right mufflers at the sky to do it), which became a little over 3/8" when I pulled the engine later. This made the swingarm pivot to the right about 1/2" from the bike's centerline.

With the engine out and the front of the frame lashed to the floor-mounted tire-mounting machine in the shop, and 3 guys (all 3 bigger than me) with thick water pipes (I think 2") we were able to get the misalignment a little bit over-corrected by pulling the right side of the frame back via the passenger footpeg mount (which also hangs the mufflers, hence the bend). When all was put back together, I have to run the left-side chain adjuster about 1/10 turn (distance) more than the right to make the wheels parallel (they are offset about 1/8", rear to the left).

That was over 150k miles ago. Although I see a small difference in the rear-wheel's wear pattern on the left side of the rear tire, this hasn't otherwise made the bike cantankerous to ride since then - although it has made the bike like certain tire tread patterns more than others: it REQUIRES a central groove (at least as much as the ones found in the Avon Roadriders) for good high-speed stability. It carries a Vetter fairing all the time, too. The bike handles well all over the Rockies, although I haven't raced it [as much] since the accident.

[rosewood]

That's a sad bunch of damage, but I might mention this: in 1972 (when my 750K2 was but 9 months in my hands) I was hit from behind on the right-side exhaust pipes by a Suzuki GT750 waterbike rider going nearly 50 MPH: I had just [been] stopped to avoid hitting the train (which he did). This pushed the right side of the frame forward about 1/4" (also bending the engine mount bolts and aiming the 2 right mufflers at the sky to do it), which became a little over 3/8" when I pulled the engine later. This made the swingarm pivot to the right about 1/2" from the bike's centerline.

With the engine out and the front of the frame lashed to the floor-mounted tire-mounting machine in the shop, and 3 guys (all 3 bigger than me) with thick water pipes (I think 2") we were able to get the misalignment a little bit over-corrected by pulling the right side of the frame back via the passenger footpeg mount (which also hangs the mufflers, hence the bend). When all was put back together, I have to run the left-side chain adjuster about 1/10 turn (distance) more than the right to make the wheels parallel (they are offset about 1/8", rear to the left).

That was over 150k miles ago. Although I see a small difference in the rear-wheel's wear pattern on the left side of the rear tire, this hasn't otherwise made the bike cantankerous to ride since then - although it has made the bike like certain tire tread patterns more than others: it REQUIRES a central groove (at least as much as the ones found in the Avon Roadriders) for good high-speed stability. It carries a Vetter fairing all the time, too. The bike handles well all over the Rockies, although I haven't raced it [as much] since the accident.

How did you deal with sprocket misalignment or is 1/8th inch acceptable tolerance?

I debated making some custom spacers to correct my sprocket alignment but decided to source a new swingarm as the safer option..

[HondaMan]

That's a sad bunch of damage, but I might mention this: in 1972 (when my 750K2 was but 9 months in my hands) I was hit from behind on the right-side exhaust pipes by a Suzuki GT750 waterbike rider going nearly 50 MPH: I had just [been] stopped to avoid hitting the train (which he did). This pushed the right side of the frame forward about 1/4" (also bending the engine mount bolts and aiming the 2 right mufflers at the sky to do it), which became a little over 3/8" when I pulled the engine later. This made the swingarm pivot to the right about 1/2" from the bike's centerline.

With the engine out and the front of the frame lashed to the floor-mounted tire-mounting machine in the shop, and 3 guys (all 3 bigger than me) with thick water pipes (I think 2") we were able to get the misalignment a little bit over-corrected by pulling the right side of the frame back via the passenger footpeg mount (which also hangs the mufflers, hence the bend). When all was put back together, I have to run the left-side chain adjuster about 1/10 turn (distance) more than the right to make the wheels parallel (they are offset about 1/8", rear to the left).

That was over 150k miles ago. Although I see a small difference in the rear-wheel's wear pattern on the left side of the rear tire, this hasn't otherwise made the bike cantankerous to ride since then - although it has made the bike like certain tire tread patterns more than others: it REQUIRES a central groove (at least as much as the ones found in the Avon Roadriders) for good high-speed stability. It carries a Vetter fairing all the time, too. The bike handles well all over the Rockies, although I haven't raced it [as much] since the accident.

How did you deal with sprocket misalignment or is 1/8th inch acceptable tolerance?

I debated making some custom spacers to correct my sprocket alignment but decided to source a new swingarm as the safer option..

The sprocket misalignment issue of the CB750 at high throttle openings taught Honda a great deal about sprocket tech, circa 1970s. The results of it were: all Honda's [own] sprockets received tapered tooth tips (on the sides of the teeth, halfway down the tooth) on both front and rear sprockets, to deal with chassis misalignments under heavy throttle. While it was a taciturn admission that the early 750 frames were...a little soft...it ended up delivering up to 5% more HP to the rear wheels of all of the SOHC4 bikes first, then all Honda's chain-driven bikes after about 1980. Soon after, Suzuki (and eventually Kawasaki) did the same with their branded sprockets. The result was greatly increased chain life (so long as they were not O-ring chains) and power transfer.

Some of these details are disclosed in My CB750 Book: there was, for the 750 in particular, additional base-circle changes to the rear sprockets, along with shortening of the tooth tips on all sprockets (by 2mm). For my part on those bikes I 'touched' in those days, i ground many, many sprockets for those owners who wanted to "try this tech out", and no one was ever disappointed: the biggest surprise to some was how much longer the sprockets lasted: not intuitive when you're shortening tooth tips, but physics don't lie. It also helped with slightly loose and misaligned swingarms.

[rosewood]

After some research I found a couple of places south of where I live that could help correct the frame. The closest to me was a guy who had adapted a car chassis jig to accept motorbikes. It looked like a decent hi tech setup with electronic measuring read outs..He was the more expensive option but also closer for convenience. I still needed to finish the front end which involved tapered steering head bearings and rebuilding the front forks. My fork stanchions had seen better days and had worn through the chrome plating. After dismantling I found both stanchions bent probably another casualty from the front end collision. I found cruzin image offered these for a 550f which were different to other 550/500  models. He had blocked me after questioning the piston ring kits so I had a colleague purchase from ebay on my behalf. I gave the fork lowers a quick polish and rebuilt them which went smoothly, also turned up some replacement top fork nuts to replace my rusted chrome ones. Installed on the bike it was a roller again and I loaded it up to get the frame sorted, it was an expensive exercise but at least I had confidence the frame was as it should be..