Topic: 1978 CB550K Brat Build - My First!

[Smackychot]

After many ups and downs, I finally got a CB550! So excited to take her apart and tinker until my hearts content.

Planning on full front (and maybe new rear) fender brat build. Focusing on performance upgrades and reliability improvements. With some fun engineering ideas I want to try. The idea is to look as vintage and clean as possible, while hiding some modern luxuries, and modern improvements.


First off, i am gonna do a tear down and see whats good and not. And get her running or see what needs done to get her running. No idea of her maintenance history, or any of that. So ultimately, a full tear down of the motor is in order to see how everything is. I'm excited. 


The day I brought her home. Lots of miles, ~30,000, but started up briefly, and pretty clean overall. And cheap.

Many thanks to my assistant, Loki.





The speedo is in km/h? It was titled in new york, so maybe originally a canada bike?


Tank has a little dent, and big dent. And needs repainted.




Started to take stuff off. Looks like a slip on MAC 4-2 flare set?



Carbs were a pain to get off. They seem to be leaking, so i will need to learn the ins and outs of these soon enough.




Still getting a feel for the bike and how its put together. And thinking of what I want to do exactly as my "build".


Regardless, I love it so far. These bikes are fascinating, and so good looking in any build.

[SOHC4 Cafe Racer Fan]

Good bones to start with.  What performance upgrades to you have in mind so far?

[Smackychot]

Good bones to start with.  What performance upgrades to you have in mind so far?

Just a basic outline as I continue to research and learn.

Mostly overall tune up things to start. Port matching, valve job, polishing overall.  Carb rebuild and tune. Possibly airbox modifications or a custom filtered velocity stack to maintain as much street ability while getting cleaner looks.



Forks and rear shocks will need addressed. Possibly for a modern swap. As much weight reduction as possible. Brake upgrade. And then hopefully my permanent magnet alternator solution which should free up weight and make it kick only.



EDIT:

I was reading some people doing a Cb650 engine swap into the 550 frame (and used 750 carbs). Like the idea of that as CB650s around me are super cheap. So i can easily steal the motor, and sell the rest (or use select bits)

Only problem for me is the CB650 not having a kick start.

(One of my main project goals, is making the PMA for these 550s to allow me to have a super simple electrical setup. I should be able to make it a kick only bike. Combined with a nice solid points set up, and more modern improvements (leds, better quality brakes, etc) should make it a very trustworthy machine with less failure points than normal.)

I've yet to dive enough into the differences between the two to see if a kickstart mod is easy or not.

But then i found this thread which really tickles my fancy...

http://forums.sohc4.net/index.php/topic,13519.0.html

[SOHC4 Cafe Racer Fan]

A kickstart mod is possible but very challenging.  It requires mating the bottom end of a 550 with the top end of a 650.  A couple of members have accomplished it, but I am not certain of the reliability. 

It's much easier to simply swap in a 650 motor preferably from a 1979-80 model (if you want to use 750 carburetors, you will need to used the head from these years).

[Smackychot]

A kickstart mod is possible but very challenging.  It requires mating the bottom end of a 550 with the top end of a 650.  A couple of members have accomplished it, but I am not certain of the reliability. 

I can't imagine it being much less reliable as long as all the surfaces mate correctly, and any mods to be done are done.

I won't go crazy on producing lots of power, so think the bottom end would hold up fine. I mainly just want more yummy torque

[flatlander]

if you want to keep the kickstart and essentially just want a beefed-up but reliable 550 you can also check what i did, which results in this:
http://forums.sohc4.net/index.php/topic,134863.msg2025864.html#msg2025864

a list of the engine mods is here: http://forums.sohc4.net/index.php/topic,134863.msg1719759.html#msg1719759
apart from the cam and exhaust which i switched since then. there's  more detailed info in the thread itself.

[SOHC4 Cafe Racer Fan]

A kickstart mod is possible but very challenging.  It requires mating the bottom end of a 550 with the top end of a 650.  A couple of members have accomplished it, but I am not certain of the reliability. 

I can't imagine it being much less reliable as long as all the surfaces mate correctly, and any mods to be done are done.

I won't go crazy on producing lots of power, so think the bottom end would hold up fine. I mainly just want more yummy torque

If you think it's an easy thing to do, check out haulages' thread: http://forums.sohc4.net/index.php?topic=40414.0

[Smackychot]

Slowly I am continuing the tear down, and forming a gameplan of what I want to do.


Got the cluster, and headlight off, and exposed the giant harness mess that will be turned into a invisible clean system.


These will both be looked over and freshened up. Most likely will go up on my ebay to help fund the engine overhaul. Someone else would find use for them.


The seat cleaned up well with some light lemon oil. Proper treatment will make her good looks last longer.



I drew first blood.... Tried to unscrew the cable. Gave a little too much pressure to break loose the screw. Or that alum is piss poor after 30k...



Cleaned up the back of the gauges with a simple white scotch brite pad during my breaks at work. They look fantastic.