Adventures in Electrochemistry

So I know it has been a while since my last update, but before summer arrived in full swing and my other bikes started getting all of the attention, I spent a large portion of time trying to clean and replate some of the smaller specialty pieces I had taken off the bike with zinc.

This involved two steps, the first being trying to get all of the rust off of a part.  My soda blaster had been doing well for light to medium rust, but the heavy rust on this rear brake brace was rather stubborn.

 This is what I started with, heavy surface rust and pitting.  What I did was use an old computer power supply tied to four pieces of iron rebar on one lead and a piece of wire suspended in the middle of the bucket.  The part was attached to the wire and submerged in a salt and water type solution that would allow electric conductivity.  Simply turn on the power supply and the rust process is essentially reversed and the rust cakes on the rebar.  This doesn't fix bad rust pitting, which I had a lot of, but it is a start.  Once the piece ran for a day or so you pull it out and scrub it with some steel wool and you get this.

You can still see some of the rust pitting, but it is a huge improvement.  Once I had this I took a dremel and made sure I had all of the rust off (there were a few little spots that were still rusty from air bubbles being there etc) and dipped the whole piece in moderately concentrated HCl, this acts as a strip for the factory plating (in this case either Zinc or Cadmium) and makes sure your part is down to the bare metal.

Once this is finished you are ready for plating!  The plating apparatus I made is similar to the rust removing bath with high purity Zinc roof strips in place of the rebar and the polarity of the power supply switched so our electron are moving in the opposite direction.  the part is submerged and allowed to run for 10-15 minutes (you don't want all of you tolerances messed up by too much plating).  This is the result.

OK, that doesn't look very nice, but here is the trick.  If you take that and scrub it with a brass wire brush under some water you get this.

I then ran the part through the zinc plating process for a second time for a nicer finish.  Notice there is still some pitting that kind of lets the piece down, but it is a huge improvement and is more then adequate for this non concours restoration.

I am going to do this process and every currently zinc plated fastener that is surface rusted, but here is an example of the factory finish in good shape and the replate for some exhaust bolts.

Factory plating is on the top and the replate is on the bottom.  The black on the end of the replate nut is heavy pitting from rust, which is why I have the extra factory bolt.

Brake master cylinder

I have had the brake master cylinder of the bike for a while and have been putting off working on it since it is not a stock component.  From what I can tell it came off at mid 80's Yamaha, but isolating it enough to figure out which rebuild kit was difficult.  Even the dealer couldn't give me a decent idea.  Well I decided to tear it apart and inspect the seals and see if by some chance it didn't need to be rebuilt.

Here was the state it was in:

There was a lot of corrosion on the outside from the brake fluid sitting in the system, but I was happy to find out when I opened it up, that the bore was clean and the seal were still pliable and looked good!  Well this saved a lot of time and frustration.  So i soda blasted the body, and wire wheeled the rubber coating from the handle and repainted the whole thing, below is the result.

Next up is removing the rest of the front brake system and cleaning up those.

Finishing the gauge cluster

So the gauge cluster was my first big sub unit that needed to be reworked and repaired.  Here is the state of things before I started.

Cosmetically, it was in rough shape with most of the black paint gone from the gauge backs and the aluminum frame.  Underneath it got worse, each of the center four indicator lights sits in a rubber tube that at some point had filled with water and caused the bulb and holder to rust away in some cases!  Fortunately, there are several online suppliers that make many reproduction parts for this bike.  So I ordered 3 new bulb holders and cut and soldered new bulb holders in place.

Here is a new holder along side one of the rusted out holders.

Here is the finished product reassembled, looking good.  They do make reproduction face plates for the gauges and mine is slightly nicked up, but I like it that way and think I will keep it like that for now.

Exhaust pipes

Its been a while, lots of things over the summer, new bike, patio, Subaru head gasket job, baby on the way, motorcycle fell off the list.  I did get a chance to work on the expansion chambers, removing years of two stroke oil and dirt baked on to form a concrete like layer.

This side had some light surface rust, but it cleaned up real well, those other side on the other hand had a few surprises.  Here is what the final product on this side looked like:

The other side had a few issues.  It looked OK at first glance but as I scraped away the layers of grim i found several small holes that I could stick my screwdriver in.  In a 4 stroke bike this would be usable, but since the expansion chamber provides vital back pressure for the engine to run, holes are a big no no.  Fortunately, my new favorite place in the world, Sport Wheels salvage has a few bikes that are identical to mine that I can pull parts from.  I found a replacement that was in amazing shape for about $70.  Not cheap, but better than what I have been seeing on Ebay.

Next maybe I will tackle rewiring the gauge cluster, once I have fixed the gauge cluster in my truck that is.