Quick update

I need to clean the engine from years of built up grease and grime. I'd like to invest in a bead blaster but that'll probably have to wait a while. For now i took the ring that holds the exhaust pipe on and ran it across a wire wheel. It cleaned up nice I think. problem with the wheel is that it doesnt fit into tight spaces, and the dremmel tool I used on this piece is flimsy and breaks easily (I used a fresh one on this piece and it was shot by completion).  If anyone has a bead blaster that wants to help a brotha out, please let me know...

Bike stripped down and engine removed

I got all the bits and pieces successfully removed and baggied up. Nothing left to do but pull the engine (well, and the wheels and swing arm). I have no idea how one normally removes an engine, but I doubt this is the propper way. I layed the bike on its side and removed all the bolts and voila!
Most of the pieces below will never end up back on the bike but having spares and or options is always a good thing. 

Once the engine was out I began the process of taking it apart. I opened up the top side panel and pulled out the overhead cam that opens the valves. Upon doing this I dropped the cam drive  chain into the crank case. Oops! 5 frustrating minutes of fishing around with an allan wrench and I finally got it back out. Once I got the cylinder head off I was able to see my first major folly...
A rookie mistake (for a rookie bike builder:) never use the blunt end of a drill bit to try to tap-out the stuck piston through the spark plug hole.
I was happy to see the piston was not mangled and none of the rings were off. I used a 1x1 piece of wood and a hammer to tap the piston free from it's rusty tomb. It finally broke loose and the cylinder was free to remove and inspect. There was a ring of rust where the piston rings were frozen, but I was able to clean it with wd-40 and a little elbow grease. The cylinder looks pretty clean so I am going to try to put a new piston in and hold off on boring it out.  Still waiting on that carburetor...

The bike has been cleared of all bee's (I hope), so next up is the electrical system. I opened up the headlight and found a rats nest of wires. Fortunately all were color coded and appeared to be un touched by unskilled hands. Despite the color codes (each and every wire has a different color and stripe combo, which coincides with the Haynes manual I purchased on ebay) I decided it was best to label and photograph everything if I am ever going to get this rewired.

I pulled the handlebars tac and speedometer off, I removed the battery box and air filter - not sure if any of this will end up on the final product. Oh, did I mention what my plans are for this bike? I plan on building a mini cafe-racer. Somewhere in the near future, I'd like to build a british cafe-bike, but I need to do a practice run on something more affordable. Hence, the cb125. Odd choice for a cafe bike you say? Well do a search on cb125 cafe bike and you may see some that look like this one or one of these. Yup all cb125's.

Once the air filter had been removed I popped off the carb and had a look. Ouch, not so good! The white crud in the picture below is the result of 20 year old gasoline. I let them soak in carb cleaner over night though the next day I was still unable to get the parts moving with out chipping internal parts so I ordered a new aftermarket carb from ebay.

The engine also showed signs of major build up so I soaked that in carb cleaner as well. At this point I seriously began to wonder if this engine would ever run again. Remember, the engine IS stuck so I have no idea if it is rusted or if it was run without oil (the latter being much worse). Only one way to find out...

Starting point

I've been wanting to rebuild a trashed motorcycle for sometime,  just to check it off the list of "things I must do in my lifetime". I have a couple of bikes (all of which I acquired for free over the years (2 bikes from family members and one incredibly great barn find). Anyway, the bikes I have all run well and since I really don't know what I'm doing, I just can't bring myself to dismantling something that works fine... at least for now.

This project had to be something that had parts easily available and small enough that I wouldn't get in over my head. After a few weeks of scouring ebay and craigslist, I found a 1974 Honda CB125 for $200 WITH A TITLE! The engine was described as "stuck" and the rest of the bike was "as is". Perfect little project for me and my new garage. I picked up the bike from Ben Salem PA and was pleased at how complete the bike appeared to be. While a lot of parts would have to be fixed or replaced, at least I know what goes where.

I got home and immediately started tearing into the bike, photographing every step so I'd have a record of what went where. All small parts were placed into ziplock bags with labels. 

As I began dismantling the bike, I noticed what appeared to be lint all over one side of the bike. Looks like the bike was parked in front of a dryer vent for sometime. Mud and leaves also caked the engine and frame as well as the usual rust spots - however, nothing (besides the seat cushion) looked unusable (I kept the seat I kept in case I'd find use for the pan somewhere down the road.) 

I pulled off the tank and it sounded felt like it was half full of dirt. This turned out to be rust. Below is a picture of what came out when I took the cap off:

Under the tank I discovered an old wasp nest. Nice! Imagine if there had been wasps in my van when I drove home?

A couple minutes later I was taking off the tail light and low and behold, another wasp nest! When I went to pull it off I was shocked to be face to face with a live bee. Whoa, I had driven and hour with these bees in my truck - windows up with AC on!. At this point I grabbed a hose and bathed the bike from a safe distance and called it a day.