30 December, 2013

Headlight brackets

I fabbed up some headlight brackets for the project bike.  I needed something to mount the CB160 headlight assembly, to the S90 forks. I decided to build up a jig, to allow me to bend some aluminum into a clamp shape, with ears to bolt up to the headlight housing.

The jig is a piece of tubing with a piece of flat stock welded to it:

I used a piece of 1.5" wide aluminum stock, bent 90-degrees on the end to mount into the clamp built into the jig:

I used the sheet metal brake that Mr. A. made me a couple months ago.  It worked perfectly to make the 90-degree bend.

Pair of clamps mounted up, and bolted to the headlight assembly.  It clamps very nicely around the fork tubes, and can easily be adjusted up or down.  

Next project will be a taillight housing assembly, that will mount to the back of the wooden seat/cowl.

29 December, 2013

Headlight teardown

After a bit of fitting, standing back and looking, and more fitting, I've decided to use the headlight assembly below.  I think it is an early CB160 housing, with a big oval speedometer.  It also sports an old school headlight, with genuine "made in japan" Stanley glass lens.  

I managed to gently pry away the thin retaining ring, and pull the entire assembly apart.  The chrome plating on the inside of the reflector has flaked away, so I'll need to fix that.  But the lens itself is in great shape, as is the chrome trim ring.  

I've already deflaked the reflector, wired brushed off some rust, and dipped it in muriatic acid to eat away the rest of the rust.  Then I'll either spray the reflector with some chrome paint, or lay down some aluminum foil.  I'm thinking of "ambering" the lens too, using some amber colored stained glass paint that Krylon sells.

27 December, 2013

Rebuilt carb and heat shield fabrication

I assembled the rebuilt carb on Christmas afternoon.  After an overnight dip in the carb goop, I ran everything through the little ultrasonic cleaner.  Then I gave the body of the carb a simple burnishing with a small brass brush on my little rotary tool.  I wanted it to have a dull grey appearance, and it does just that.

Yesterday evening I fabricated a simple heat shield for the exhaust, using a scrap piece of aluminum.  Hand cut, hand hammered, and hand finished with some 000 steel wool and Gojo brand hand cleaner as the abrasive.  It gives it a nice slightly dull, yet smooth finish.  I also like the slightly lumpy look from the hammer marks.  No sharp edges either, as I managed to roll the edges for a clean, smooth look. 

24 December, 2013

Carb tear down

I found a pair of Keihin PW20 carbs in my box of carb parts.  I'm hoping to make one good carb out of two, for the project bike.  I got them disassembled and in the carb dip for an overnight soaking.

I'm also modifying the original intake to accept this bigger carb.  Instead of a 15mm stock carb, with it's tiny intake opening, I'm going to modify an old CB160 intake manifold so it can get welded up to the hogged out stock manifold.  Along with the exhaust, some porting, and higher compression, this Yamaha GT80 engine should provide ample motivation.

Project bike updates

I fabbed up an exhaust a couple weekends ago. Since this a two-stroke motor, I ran through some calcs to determine the size and shape of the various cones for the expansion chamber.  I built everything out of 3" exhaust tubing I got from NAPA.  That means cutting down and shaping the cones by using good old brute force.  I wanted to do something different, so I ran the exhaust through the middle of the frame.  Making the divergent cone was trickiest, as it needed to bend 90-degrees, while still coning down to its final diameter.  Lots of pie cuts and welding.  Still needs some finishing work, but the entire thing will get wrapped anyways. 

The last three shots show a wood seat and rear cowl I built, using layers of poplar.  Lots of shaping and sanding, finished with five coats of gloss urethane.  Still need to make a rear mount, license plate bracket, and figure out a taillight.

06 December, 2013

DKW 125

I couldn't resist rescuing this beast, a 1970 DKW/Sachs 125 motocross bike. No plans for it yet.