Topic: rosewood's cb550F restomod - damage repair and frame mods/welding-the fun stuff

[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..

[rosewood]

With the bike back from the having the frame straightened I still had some repair work to do around the swingarm. I had always planned for this to be a cafe style bike (many years later now I somewhat regret this decision, but the bike was in such a state when I got it sourcing decent replacement parts was never going to end well financially.) So there were also some modifications to get my head around.

I wanted to run rear sets but if anyone has done this on a 550F will know its not as straight forward with the 550f exhaust collector tucked up close to the brake lever. The brake pivot tube is also longer so there are some subtle differences which makes most off the shelf options tricky. I actually mocked up a solution with laser cut acrylic parts to get me head around what was required. I wanted to use the original exhaust and this resulted in me fabricated and extension to the collector to work with my cone muffler.

One of the reasons for this project was to learn how to weld so I took this as an opportunity to make a pie cut extension to the manifold. This would give me clearence to the exhaust if I ever wanted to fit rearsets.

Excuse the weld job, this was my first time playing around with a TIG welder, its not pretty but I figured it would get the job done for now..

[rosewood]

I had sourced a frame hoop I think from Harisuluv from this group. So next was time to build up the courage and take to the frame with the angle grinder, I also removed the passenger peg mounts. Since the frame was being welded I decided to fabricate some custom mounts for rear sets on the frame. I also made a mount for an exhaust hanger.

For all the frame welding I called on a friend who is a fabricator for the Navy here in NZ. He does amazing work and I always wanted to use his skills on one of my projects. He also sorted the swing arm damage. I don't have images but after some more grinding and filling the repair work unnoticeable.

I was over the moon with his work, there were some other mods I added myself later but all the major work was now done..

[denward17]

Wow!

Nice work.....

[HondaMan]

I think Honda's production guys would be jealous of some of these mods...?

[rosewood]

Thanks guys, I wouldn't say its anything too special, plenty of impressive work from others on this site..

Anyway I found the last of the frame mod pics.......I wanted to move the ignition key from the top triple which was all being cleaned up to under tank. I had sourced an emgo switch to replace the original and was aware of using a relay with this, I fabricated a tube/holder and also some tabs on the rear hoop to mount the aftermarket indicators the PO had supplied with the bike. I managed to get these welded onto the frame myself which worked out ok..

While all this was going on I was also working on some other custom parts. I had always wanted to make some carbon fibre parts so the obvious place to do this was the rear cowl. I'll share this in the next post as there are a few pics to go with it.

I also had an idea to make a rear splash guard out of carbon fibre. I shared this back in the day so i will link the post here if anyone is interested, it is still the favorite part of my build to date..

http://forums.sohc4.net/index.php/topic,174839.msg2034673.html#msg2034673

[rosewood]

Back to the cowl...I spent a ton of time deciding the profile of this, would spend hours in the garage staring at the bike, sketching on images playing around with different ideas.

I shaped foam as most do..Once happy with the shape I wrapped it in fiber glass which was the start of the plug to pull a mold from. The pics wont show but I spent a ton of time on this, shaping, filling, sanding etc. I decided to do this properly and used gelcoat and polyester resin to make the two halves of the mold. Working with carbon fiber is alot harder than fiberglass due to its stiffness, the key is being prepared when you do the lay up having everything cut and ready to go so you don't waste anytime. Got it laid up and into the vacuum bag. I was using a recycled fridge compressor as the vacuum pump and let it run over night. To my surprise when I demolded the part it was very very clean with minimal voids in the outer surface.

I also had to figure out how to connect this to the frame, I decided to make a base also from carbon fibre using the frame/hoop section as a mold. This was just a hand lay up and I will let the pics do the talking but cut polyprop sheets of plastic and used weights and clamps to hold the carbon down and get the detail I needed. My plan worked a treat and I had a carbon cowl and base. I joined them together with epoxy and reinforced the join with more carbon fiber from the inside..

[newday777]

Nice job done with the key switch mount.
Beware of that small spacing of the rear tire to the hoop. Sitting on the bike and riding over bumps will likely contact the tire and frame causing damage or worse, you don't want to get into a slide from tire lockup.

[rosewood]

Nice job done with the key switch mount.
Beware of that small spacing of the rear tire to the hoop. Sitting on the bike and riding over bumps will likely contact the tire and frame causing damage or worse, you don't want to get into a slide from tire lockup.

Thanks, there is more clearance than that image shows. It was just to show under almost full compression the contour of the rear guard with the tyre. However I did overlook this issue you mention a bit which ill talk about later..

[rosewood]

I still needed to make a seat base to go with the rear cowl...sticking with the carbon fiber theme I taped up the frame to use as a mold again, I wanted to run the factory airbox so I covered that with foam to give me clearance with the top duct once installed. Again this was a hand layup and to get the detail with the carbon I weighted it down with polyprop sheet plastic and the use of sand bags from the kids sand pit. It all looks a bit janky but it worked and I managed to get a decent part from it. Painted the underside with a coat of epoxy to tidy it up, the top will be covered with foam...

I was also missing the stator cover plate thing...I modelled something, Cammed, cnc machined and gave it a quick polish. Embarrassed to say but I used the honda car logo instead of the motorcyle one lol...never mind it tells a story and I can always do another one later but probably never will..

Also purchased some cheap rear lights from ebay, I wanted something discrete, these were E marked as well. I made a mounting bracket using a water jet cutter at work to tuck them under the rear hoop...probably not the best idea which I realized later as someone has already mentioned.

Anyway things were looking good and I felt like most of the fabricated custom parts were sorted. I was roughly 3 years into this project by this stage.

[HondaMan]

Wow, are you getting fancy now, or what?
That's pretty cool! If you could make a 2.1"x4.1"x1.25" deep hole into the bottom of the tailpiece, I could send you an electronic ignition that would fit right in there, making your points last forever...riders with the CB750F0/1 bikes like to put these into their tail trunks, out of sight.

[rosewood]

Wow, are you getting fancy now, or what?
That's pretty cool! If you could make a 2.1"x4.1"x1.25" deep hole into the bottom of the tailpiece, I could send you an electronic ignition that would fit right in there, making your points last forever...riders with the CB750F0/1 bikes like to put these into their tail trunks, out of sight.

Mark I already have one of your electronic ignitions, its currently tucked under the battery strap for now. Apart from the mods you see here I was trying to keep everything stock-ish. I have changed design direction since these pictures were taken which I'll share as I progress these posts...Probably why 10 years on its still not finished 

[rosewood]

Ok with most mods done to the frame I felt it was time to get things to the powder coaters so I could start putting it all back together...I chose satin black for most parts..

I also went on a tangent in the background about this time.....picked up a pair of old koni's locally for a 750 which I rebuilt. I shared this at the time for anyone interested:

http://forums.sohc4.net/index.php/topic,173257.msg2030918.html#msg2030918

After realizing these would be too long/tall for the 550. I found a set specific for a 550 from the Netherlands, one of the shafts was worn which was disappointing as the seller assured me the shafts were good. I found a spare on ebay which I used for parts to rebuild these. I had the bodies for these 550 ones powder coated at the same time in gloss black which you will see in the following images. The rebuild of these 550 ones were never documented but they came out great as you will see later..

Still have the 750 ones sitting in a box somewhere which I should try and move on...if anyone in NZ is interested hit me up..

It was about this time my wife was pregnant with our second child (the first was 6 months old when I started this project thinking I could get it done in a year... ) so the push was on get it finished before the arrival, one can only hope in these situations..

[HondaMan]

That satin is sharp (and my favorite)!