Topic: '78 CB550K bratstyle/cafe build

[bcollings]

So I bought a '78 CB550K in early August and have been putting every spare minute into the bike over the past two months.  I've been meaning to post a build thread for a long time, but I'm nearing the finish line so I thought I'd finally slow down and post some pics of the progress so far.  The bike wasn't in great shape when I got it.  The bike only had 12k miles on it, but it clearly sat for awhile and barely kicked over after a dozen+ tries.  Carbs were leaking gas all over the place, oil leaks, seized front brake were the initial items I had to take care of to get the bike in running order.

Here's a pic from when I bought it...previous owner put clubmans on it but wasn't up for the mechanical work given the two austin healey's and an alpha romeo in his garage:



Here's an initial sketch/photoshop drawing of how I wanted the bike to look:

[bcollings]

First up was a carb rebuild.  Gas was leaking out of the overflow tubes and out the float bowl seals.  A huge resource was Brian Barnes' Carb Rebuild Guide (https://s3.amazonaws.com/sohc4-tech/CB550/PD46A_rebuild.pdf).  Although this was intended for Keihin PD46A carbs, it worked just fine on my Keihin PD46C carbs which are used on the '78 CB550K...very little difference, just use common sense.  The biggest differences are in the carb specs...for my PD46C's the specs are:

Float height: 12.5mm (although I set mine at about 13mm, since at 12.5mm the float flange was not fully depressing the button on the float needle)
Stock Main Jet: 90
Stock Slow Jet: 42

I'm doing a 4-1 Mac exhaust (couldn't find a Kerker or Yoshi) and k&n air pods, so I did a rejet to 105 mains.  Needles are in stock position at #2, and it's running fine so far but I haven't put many miles on it...will update the thread if I make any tuning adjustments.

I followed the rebuild guide above to the letter, and it worked out great.  I would highly recommend buying the Genuine Honda Gasket Sets and replacing every piece of rubber you can...they're expensive but you won't regret it, I learned the hard way.  I also replaced the float needles since all 4 carbs were leaking out the overflow tube.

Another thing I learned the hard way was how to get good choke action once I rebuilt the carb bank.  The choke plates/arm wouldn't return once I pulled them open, and kept getting stuck on the way down.  There were two solutions to this problem:

1. Give the choke spring one extra turn...it may seem like it's twisted all the way, but another turn will work wonders
2. Loosen all the choke plates and then tighten them one by one, checking the choke action/clearance every step of the way

Here's a few photos from the carb rebuild:

Untitled by bryan540, on Flickr

Untitled by bryan540, on Flickr

I put new rubber manifolds on, since mine were cracking.  The new ones were REALLY tight, I had to get them loosened up in pretty hot water several times and needed a friend's help to get the carbs seated fully on the manifolds...don't force it, it takes time.

From here I installed my air filters.  Originally I got the K&N 'STYLE' shorty air filter pods from DCC.  Key emphasis was 'style'.  They were terrible.  When I sprayed them with filter oil on one side it blew right through to the other.  They were basically screen-door mesh on the inside and I didn't feel comfortable putting that on my bike.  I cut my losses and shelled out the cash for genuine K&N filters, and got the K&N RC-0844 circular style air pods.  For the CB550K, you need a shorter air pod otherwise it hits the frame on carbs 1 & 4.  These fit, EXCEPT they nearly touch eachother since they are so wide, which ends up bumping into the moving choke arm in the middle of the carb bank.  I ended up shaving some rubber off the filter that sits on carb 2, and bent in the filter a little bit so it barely cleared.  If I did this again, I'd get the oval style to make sure everything cleared.

Then I installed the chrome Mac 4-1 megaphone exhaust...I looked all over for a Kerker or a Yoshi, but it's really hard to track down for a 550...if anybody has one I may still be interested:

Untitled by bryan540, on Flickr

Untitled by bryan540, on Flickr

[bcollings]

Next up was fixing my front brakes.  The front brake was completely seized up and stuck, but the master cylinder seemed to be applying good pressure to the brake system so I was pretty sure my problem was in the caliper.  Opened up everything and there was a ton of gunk in the caliper and the seal didn't look so great.  Luckily the piston wasn't too pitted or anything.  I replaced the piston seal, did new steel braided brake lines and then replaced the front brake pads, since the current caliper-side pad had some weird indentations in the middle.  I got a new set of EBC brake pads, put everything back together and the brakes were still getting stuck.  I had no idea what to do, so I took it to my local vintage mechanic to figure it out...Turns out that although the EBC pads are pretty close to OEM, they put a lot of heavy paint around the outside and it causes them to not retract after pressure has been applied toward the pad.  Had to grind off the side and even the back of the pad to get it to work.

While I was taking off the front brakes, I took the opportunity to remove the forks and paint them since they were badly pitted.  I used VHT black epoxy paint and it worked great.  A little bit of 320 grit sand paper to prep and it came out looking pretty clean.

Before:

Untitled by bryan540, on Flickr

After:

Untitled by bryan540, on Flickr

Also, I don't have a fancy lift or anything, so I had to improvise to get the front end up off the ground while on the center stand...nothing a few bricks and scrap wood can't fix!

Untitled by bryan540, on Flickr

[bcollings]

The next item was to get the backend in order so I could have my seat made.  I don't have any fabrication skills, so I didn't want to chop the frame and weld a seat hoop around the back.  Luckily the CB550 has a beautiful gentle upsweep just past the rear shocks, so I chose to chop off the seat support hoop and then finish the rear end with a slim fender. 

First thing I had to do was chop the seat support and grind down a few loose tabs:

Untitled by bryan540, on Flickr
After:

Untitled by bryan540, on Flickr

Then I found a local garage builder and traded him a 6 pack of beer for a spare CB350 rear fender (mine was in decent shape and didn't want to wreck it...figured somebody else could use it).  The only problem was that it was only 6" across and the gap between my frame rails was 7":

Untitled by bryan540, on Flickr

 A buddy of mine grew up in a family of old timers, and he showed me a really simple method for spreading the fender while still keeping it uniform.  First I ground off the horizontal metal supports inside the curved fender body.  Then I placed the fender on the ground (on a towel) and using a couple 2x4's and block of scrap wood as a fulcrum, spread the fender edges to be 7" in width....here's a beautiful drawing:

Untitled by bryan540, on Flickr

Then I mounted the fender up and was really happy with the lines.  Drilled the fender for my new tail light and license plate mount as well (sorry it's a little dark...better pictures to come):

Untitled by bryan540, on Flickr

[bcollings]

After I finished setting up the lines for backend, it was time to make a seat pan.  After doing some research I decided it was best to make my own out of fiberglass.  I followed the instructions here http://www.jeffreyphipps.com/seat_pans.htm and it worked great.  I'd recommend buying an extra can of resin just in case...I added too much hardener on my first batch and it hardened up in my mixing tray after adding the first two layers.  I started with a layer of fiberglass cloth and then layered fiberglass mat on top.  If I did it again, I would finish with a layer of fiberglass cloth on top.  The bottom came out nice and clean, but the top was pretty rough from the disorganized strips of mat that I had on the last layer.

First layer of masking tape:

Untitled by bryan540, on Flickr

Aluminum foil tape added on top, plus protecting the bike with plastic...also, I used basic household wax on top of the aluminum foil tape and it worked great when it came time to remove the pan:

Untitled by bryan540, on Flickr

Here's the pan after I finished cutting and sanding the edges:

Untitled by bryan540, on Flickr

Another important thing to note, is that I didn't add the mounting bolts as I was making the seat.  I didn't want to puncture the layer of tape and risk getting fiberglass on my bike or even on the mounting bolts.  I just drilled tight holes in the seat pan after it cured and then used Gorilla Glue on the mounting bolts.  It worked great!

Here's a side view of the bike with the seat pan finished:

Untitled by bryan540, on Flickr

Then I drew up a design for a ribbed bratstyle seat and dropped the pan off with a seat upholsterer I found in town.

[bcollings]

While I waited for my seat to be finished, I tore down the front end again to do some cosmetic work:


Untitled by bryan540, on Flickr

I got some mini gauges with built-in LEDs from DCC, and wired them up somehow without incident.  It was one of the only things that had gone smoothly so far, and I have zero experience with electronics.  A HUGE help was Boulevard_beck's wiring diagram for these exact mini gauges:

http://forums.sohc4.net/index.php?topic=106175.msg1210705#msg1210705

I'm lazy and skipped the diode for the turn signals, but will probably do that at a later date.

They work!

Untitled by bryan540, on Flickr

Also, I installed drag bars and new all-chrome levers a little earlier in the build, but forgot to mention it.  After I finished wiring the mini gauges, I dropped the front forks out and removed the stock headlight brackets/turn signals.  I replaced them with chrome brackets and some mini LED turn signals, and then added fork boots.  They only make fork boots for the earlier model cb550s, so I was having a lot of trouble finding ones that would fit right.  I ended up ordering genuine Hondas fork boots for the 76' and earlier CB550s, and although they didn't fit over the notches in the fork braces, they ended up fitting quite nicely over top of my original fork dust covers and rested evenly on the bottom of the triple tree. While I was in the middle of finishing mounting the turn signals and headlight, my seat got finished!

Untitled by bryan540, on Flickr


Untitled by bryan540, on Flickr

[bcollings]

Next on the list was the tank.  It had two big dents on the right side, plus I needed paint.  Ended up finding a russian autobody shop who pulled the dents and did the paint for $200 cash.  They gave me a whole mess of paint chips and I narrowed it down to a few options.  To match the tan/brown seat, I wanted to go with a dark blue with a glossy finish.  Here were some of my initial choices, ended up going with the option on the right:


Untitled by bryan540, on Flickr

They got the tank done for me in two days, just enough time to wrap up some wiring on the rear end, paint the rear fender black, and mount up the headlight:

photo 2 (2) by bryan540, on Flickr


photo 4 (1) by bryan540, on Flickr


Untitled by bryan540, on Flickr

Really happy with how the color turned out, just need to add some chrome trim on the bottom of the tank to tighten it all up! 

Next on the list is new tires.  Putting Dunlop K70s up front and K81s in back.  That'll be done this week and I'll post a few more pics.  After that I think I'm going to enjoy riding it for a few months before it gets to wet outside.  Then I'll put her back in the garage to do some electronics work and give her a clean triangle.

[Inferno333]

That is a great looking bike bud!

Thank you for posting the build log.

[Sprocket75]

WOW! Really nice build and beautiful bike! Great job on the seats and that color is slick!

[brandEn]

Looks really cool. I like that seat a ton.

[bcollings]

Thanks guys, I really wanted to do some personal touches but still staying true to the original lines of the bike.

One thing that's been bothering me is the sound of my exhaust. I have a mac 4-1 megaphone and I think it sounds like #$%*.  Debating between two options and would love your input:

1. Cut the baffle in half and keep the rear section intact
2. Drill the baffle and wrap with fiberglass insulation

Obviously #1 seems a lot easier, but wondering what the downsides could be.

[brandEn]

How about remove the muffler and install a cone exhaust from Cycle X?






Actually its cheaper to get it right from the manufacturer
http://www.coneeng.com/motorcycle_components.html

[steakCB550K]

Great job on the bike, I've been wanting to do the same to my 78 cb550K.  Thanks for the inspiration.

If possible do you have a pic of the modified 350 fender without the seat pan?
Thanks!

[bcollings]

Great job on the bike, I've been wanting to do the same to my 78 cb550K.  Thanks for the inspiration.

If possible do you have a pic of the modified 350 fender without the seat pan?
Thanks!

Couldn't find a photo, but it's pretty straightforward so I drew up a picture real quick.  I chopped the CB350 fender roughly in half, secured it to the original fender mounting bolts, and then cut the plastic interior fender to meet cleanly with the edge of the CB350 fender.  There's not much to hold the top of the plastic fender in place, but once you get the seat pan on it's not going anywhere.

Here's the drawing:

Untitled by bryan540, on Flickr

[Bru-tom]

good job man! my tank is exactly the same colour! 

[bcollings]

good job man! my tank is exactly the same colour! 

Just saw your build thread...you've got excellent taste sir.  Did you choose on gold or silver for the tank detail? And are you going with a decal or painted pin-stripping? Thinking about doing something similar on my bike.

[Bru-tom]

thank you

i have just finished designing the decals i will have cut from cast vinyl. I am still unsure whether i will just stick them on and clear coat over them (like the originals where) or just leave them stuck on the surface and when i get tired of them, replace them with something fresh.