Topic: 1975 CB550 Rebuild Highlights

[kwinabram]

I've owned a 1976 XR75, 1984 XL350, 1983 CB550 Nighthawk, 3 Accords ('76, '85, '91), 2000 Odyssey and 2009 Fit.  It had been 25 years since I owned and motorcycle and I bought this non-running 1975 CB550.  I want to document my re-build during the 2015-16 winter months in hopes that some of my learnings will help some of you.

[kwinabram]

Background: 

In short, the only thing I have ever restored was a 1961 Cub Cadet garden tractor (I have pictures if someone asks :-).   I saw some pictures of older bikes (Honda 350's) that reminded me of flat track racers and I thought they looked really cool.  Howevever, I noticed that when people were sitting on the 350's (which were stripped down), they looked really small... So I started looking at 450's but they seemed small too.  So, I narrowed it down to 550's or 750's AND I did not want a hump on the back.  And then a key decision was made:  When I saw bikes "hollowed out" in the air box area, I thought it looked strange (and kind of unfinished) but I really liked it.  Since the older 750's had a dry sump, the only way to get this "hollowed out" look was to eliminate the tank (which many people suggested was a really bad idea) or place the tank in a "cafe rear hump" and I definitely didn't want a hump!  So 550 was they way to go.  And since my last bike was a 550 Nighthawk, the search was on via Craigslist for a mid '70s 550 (and a bonus if it was orange).

After a couple months of searching I found a 1975, orange with 38k miles in the spring of 2015.  It wasn't running, but looked decent and $800 later it was in my Odyssey headed home.

My goal was to keep the project under $2000, use the summer of 2015 to shake out the issues and get it rideable in preparation for a winter re-build.

NOTE:  For pictures on my iCloud account, click on the globe under my name or click here: 

https://www.icloud.com/sharedalbum/#B08GRMtznGFCh6X

[Tews19]

Tank looks nice. What are your plans with it?

[kwinabram]

Since you asked about the tank, I'll start there with my updates:

I like bikes that are completely original and completely re-done...but my personal favorite is when they are somewhere in between.  The original tank paint is not perfect by any means but looks good from 5 feet away.  So I am keeping the paint original (it's one of my favorite parts of the bike!).  The chrome trim was all there but looked really terrible so I removed it and was initially planning to replace with some from Autozone.  But after removing the old stuff, I found I preferred the look without trim even though the paint was in rather poor condition under the old trim.  So the tank is staying just as it is.

One of my first issues to get the bike running last year was to fix a leaking petcock.  I bought a re-build kit and did a ton of work to get the original to quit leaking but ultimately realized that the issue was due to worn components that can only be replaced by buying a new petcock.   Since NOS was rather pricy, I found 16950-341-671 at CB750supply.com for $40 which fit perfectly (except I think I had to buy a fuel o-ring from O'reilly's).  The thread was a 20x1.5 and I had to use some care to get the nipple very clean and smooth so that there were no leaks.  Almost 1 year later and it still works perfectly with no leaks. NOTE: this petcock only has 1 outlet and the original had 2, so I had to buy a brass splitter at O'reilly's to feed both supply tubes.

There was rust on the inside of the tank but it was still very solid.  I used the vinegar/drywall screws/ baking soda trick (just search as there are my sites which will guide you on how to do this and it does work really well) to get the rust off.  Beware that the surface will rust again INSTANTLY but don't worry as it's not a huge problem.  I used a hair dryer to completely dry mine out to stop the rusting and then I applied some POR 15 coating to the inside.  NOTE: I made a huge mistake and applied the pint of POR 15 while the tank was still warm from the hair dryer and it made the POR 15 get "thick" very quickly.  The result was that the corners now have a very thick layer of POR 15 but it doesn't seem to hurt anything...just looks terrible when looking inside.

[kwinabram]

Since this is my first time at posting on this site, I've now realized that it will be much more useful for other readers if I post my updates as new subjects.  That will keep people from having to dig through a long thread to see what they are after.  So my next posting will be:  2.5" rear rim installed on 1975 CB550.