Saturday, December 14, 2013

CL450 Racer - Repairing the Seat

To finish retrofitting my CL450/CB500T racer into a more usable road bike, I decided to axe the current racer seat and install an original seat. Unfortunately, I never had an original one, and good examples are getting rare and expensive, so I settled for a $10 example scrounged from an estate sale at an upstate New York junkyard. The pan was mostly solid except for the rear right edge, which had effectively disintegrated. However, there was enough left to repair it.

Almost looks okay...

But it was all lies!

The back corner was completely gone.

Removing the damaged portions

Reinforcing the seat strap stud

Fabricating a replacement section

Brazing on the new section

Applying braze to both sides of the joint.

Fully sandblasted

Making new upholstery hooks

Brazing on the upholstery hooks

Applying rust-proof paint.

Covering the rust stains on the cushion.

Applying contact cement

Applying the new cover

Finished and Installed!

Monday, December 9, 2013

Rebuilding a Blown Engine - Part 1

This has not been a great year for Honda engines in my garage, which I suppose is to be expected when you race 40+ year old junkyard bikes. Two of the motors, the original mill from the 1968 CL450 and the engine from my friend's 1970 CB had both suffered...fairly catastrophic failures.

Thats not so bad...

The CL450 engine developed an air leak through a worn out carburetor and burned a hole in the left piston. As for the CB450 engine? That is the result of running low on oil at freeway speeds. kaboom. 

I had already recommissioned a CB500T engine for use in my CL racer, so I decided to combine the remains of the two engines into one runner, to get my buddy's CB back on the road. Obviously the original CB engine was toast (what with half a piston floating in the case, and the piston pin welded to the conrod), so we pulled apart the CL engine with the holed piston and began cleaning.

Not TOO terrible
Luckily, most of the debris from the piston had gone out through the exhaust before the hole broke through the piston crown. What little had gotten inside had been deposited on the top of the conrod, which cleaned up easily. We swapped the good side covers, sprockets, and electrical bits from the CB to the CL, and will recondition to head for installation later. The CB head is a later model with thicker castings and stronger studs, so it is the better choice.

For the guts of the engine, we tracked down some NOS pistons, aftermarket pins and clips, and rehoned the cylinders to clean up the minor scuffing and glazing. After that, the parts went together smoothly.

Friday, December 6, 2013

Carburetor Modification Part 4

One of the benefits of installing the smaller Scrambler tank is, since it is physically smaller and sits higher on the frame, I can now perform all the carburetor tuning without having to disconnect hoses or prop the tank up. Following the results from the last round of carb testing, I determined that the idle/slow jetting is slightly rich (fixed by adjusting the air screw), the midrange is too lean, and the top-end of the bike still surges and stumbles.

Much more room now with the small tank
 I solved the midrange problem by installing the next higher-size needle jet (P-6). For the top end, rather than change the jetting, I reinstalled the sheetmetal baffles in the float bowls and lowered the float height. Both of these steps will lean out the mixture (and make the carburetors stop leaking fuel!)

The shakedown ride I took following these changes was encouraging. It now idles perfectly and accelerates strongly right off the line. There is still some stumble at full throttle, but it can now cruise at 60-65mph with no hesitation. I'm sure the correct setting is within reach, but I'll have to wait for warmer weather to really open it up and test it. The current carburetor settings are:

Mikuni VM26-8074

Main Jet: 130
Pilot Jet: 35
Needle Jet: P-6
Needle: 5F21
Air Jet: 2.0
Slide: 2.0
Float Valve: 2.5
Air Jet Turns: 2
Needle Notch: Center
Float Height: Approx 17mm

Hard at work with a cup of hot tea

Wednesday, December 4, 2013

CL450 Racer - Installing the Original Tank

When I purchased the hulk that would form the basis of my 450cc land speed racer, it was incomplete and didn't come with a gas tank.

Among other things
I had a larger CB500T gas tank installed on its original motor-less chassis, so I swapped it onto the new frame and modified the mounting points to suit. That tank served me well, until I stumbled on an original CL450 "Scrambler" tank on Craigslist.

That seat came from a junkyard and is WAAAY worse than it looks.
The inside is surprisingly clean
I was browsing for a donor tank to put onto the rolling chassis I assembled in my previous post, but the opportunity was too good to pass up. I decided to refurbish the scrambler tank, put it on its correct chassis, and return the 500T tank to its original home.

CL450 with the 500T tank

Lean and mean with its original sheetmetal
The scrambler tank weighs 5 pounds less than the 500T tank, and holds around 1 gallon less of fuel, so now the bike handles brilliantly :-D . Next up is to refurbish that seat, so I can actually use this machine regularly on the road.

Tuesday, December 3, 2013

Machine Tool Spotlight - Star Lathe

Over the Thanksgiving holiday, we picked up a vintage lathe from a friend who had snagged it at an estate sale. This one is a true antique, and makes my '40's vintage Hardinge look modern by comparison! We also picked up a small Craftsman lathe, which will be featured in another post.

This is a Star Lathe, made in Seneca Falls NY circa 1900. The bed has several patent dates cast into it, the most recent in 1896.

Original paint is still there under the grime

It is equipped with auto feed in both axes, babbit bearings, a 3-step flat belt pulley, and an auto-oiler for the main bearing that appears to have been borrowed from a steam engine. This bad boy is Victorian Era state-of-the-art.

The oiler is particularly interesting. It is made of a glass cylinder sandwiched between two brass caps. A knob on the top adjusts the size of an air hole, which alters the gravity feed rate of the oil. This allows for continuous operation without having to constantly stop and check the lubrication.

When this lathe was first produced, electricity was still relatively new and rare. Because of that, it came in two versions. The first is this one, which could be run off of a common belt or motor. The second version is treadle-powered, similar to early sewing machines.

This machine is in incredible original condition. None of the parts are damaged or excessively worn, and the original paint is still present. Therefore, I think the "restoration" will only consist of a general cleaning and re-oiling of the moving parts. I may also check the various bearings and bushings for any debris or damage before repowering it with an electric motor. Although, perhaps I could dig up a pedal drive...