Steam Engine Restoration Part 6 - Stripping the Main Bearings

The main bearings in this steam engine are made of poured babbitt metal. Bearings of this type are formed in place by loosely assembling the bearing caps with the crankshaft installed and supported at the correct assembly location. After everything has been properly located, the open gaps between the bearing blocks and the shaft are sealed with clay, and molten babbitt metal is poured in through the lubrication hole. 

Once the metal hardens, it is trimmed and scraped to its final shape. Finally, before the bearing enters service, it is cleaned, well-lubricated, and "run-in", which is a process of slowly turning the shaft and allowing the bearing to develop a wear pattern that matches the microscopic contours of the shaft surface.

The bearings in this engine were in extremely worn condition and needed to be replaced, so I used a torch to melt out the old bearing material. Then, I sandblasted, painted, and reinstalled the caps. Once the crank has been rebuilt, they can be rebabbitted.

Original condition

Removing the babbitt

Fully removed

Ready for sandblasting

Sandblasted and ready for paint

Freshly restored bearing caps installed on the engine

Steam Engine Restoration Part 5 - Valve Gear Machining and Reassembly

Up until now I had been able to sandblast and reuse all the original parts from the engine, excluding fasteners. The first part that had to be totally made from scratch was the D-valve slide rod. This is a simple steel rod with threaded ends and a smooth midsection, which transfers the motion of the valve crosshead to the valve itself. It is necessary to use a small rod for this purpose because the valve chest is pressurized during operation. The smooth rod passes through a seal into the chest, and it must remain pressure-tight at all times during sliding motion. The original rod was heavily corroded and pitted and would no longer seal correctly, so I made a new one from a piece of steel rod.

The original: corroded, bent, and totally useless except as a pattern.

Beginning the new part

Cutting the first thread on the new valve rod

Checking thread length

Cut to size

Threading the opposite side

Checking dimensions

Loosely assembled

Checking the fit

CL450 Racer - Installing an Air/Fuel Ratio Gauge - Part 4

Here is a quick video of the operation of the Innovate Air/Fuel sensor. The response time is excellent, and I have ordered a miniature data logger so that I can record the results from my rides to analyze later.

CL450 Racer - Installing an Air/Fuel Ratio Gauge - Part 3

The Air/Fuel Ratio Sensor is a high-precision wideband O2 sensor that must be installed in the exhaust. It measures the amount of free oxygen or unburnt fuel present in the exhaust gases, which indicates either a lean or rich condition in the cylinder. Normally this would mount in a standard O2 sensor bung. However, this motorcycle was built long before such technology was available in motorcycles, so it is necessary to add a threaded bung.

Spare dented exhaust header to modify with a threaded bung.

Estimating the final location

Marking out the hole

Unmodified threaded sensor bung

Carved down to match the curvature of the exhaust pipe

Drilling the port hole

Tack welded

Welding finished

Ground down and prepared for paint

The rest of the equipment

Wiring the power cord

Rough installation

Sensor cable properly routed

CL450 Racer - Installing an Air/Fuel Ratio Gauge - Part 2

Now that the gauge housing was complete, it was time to mount it to the bike. I made a simple steel bracket that attaches beneath the handlebar mounting bolts, and installed longer assembly screws in the gauge housing that doubled as mounting screws.

CL450 Racer - Installing an Air/Fuel Ratio Gauge - Part 1

The standard low-cost method for tuning a carburetor is by performing a "plug chop". This is a process where a fresh set of spark plugs is installed in the engine, the vehicle is driven at a specific throttle opening for a few miles, and then the motor is quickly shut down and the plugs are removed and inspected. By checking the relative condition of the spark plugs, such as the location of carbon deposits, the color of the ceramic insulator, and the color of the exposed metal parts, it is possible to determine the relative tune of the engine. 

Carburetors are surprisingly complex components, and are equipped with multiple jets to provide even fueling to the engine at all throttle openings and load conditions. Every jet has to be independently tuned, so it is important to maintain a steady engine speed/load in order to perform the plug readings. Acceleration and speed changes will vary the fuel circuits and jets that are used. To determine the state of tune of a specific jet, the engine must be started, maintained at the desired speed, and then quickly shut down (ideally by pulling in the clutch, killing the engine, and coasting to a halt).

The phrase "plug chop" refers to the practice of cutting down the side of the plugs so the entire ceramic insulator can be inspected. If the plug ceramic is black, the engine is running rich. Likewise, if the ceramic is white, then it is running lean. Carburetor jets should be swapped until the plug is a brownish/tan color through the entire load range.

However, this process is tedious, wasteful (you go through ALOT of plugs), and not particularly exact. It is especially time-consuming if you are maintaining a race bike, and need to tune the carbs for a variety of air filter, muffler, temperature, and air pressure variations. Rather than do things the old fashioned way, I decided to purchase an on-board Air/Fuel Ratio sensor and gauge from Innovate Motorsports.

Special Delivery!

Laying out the equipment

Panel-mount gauge

This kit includes a high-resolution wideband O2 sensor which permanently mounts to an exhaust header. Based on the composition of the exhaust gases, the sensor calculates the ratio of fuel to air in the carburetor, and displays it on an numerical LED screen. The ideal stoichiometric ratio for a gasoline engine is 14.7 parts air to 1 part gasoline. Any more than this, and the engine is running lean. Lower, and it is running rich.

The biggest problem with this kit is it is meant for automotive use, so there are no mounting kits available for powersports applications. Normally this would mount to a hole in a dashboard, so the first step was to make a robust aluminum housing to mount to the motorcycle.

Raw material

Rough Cut

Shaping on the lathe

Test Fit

Marking out the shape of the back plate

Boring the back plate

Shaping the back plate

The raw material for the gauge pod

Drilling the bottom pkate

Drilling the gauge pod body

Tapping the holes

Hogging out clearance for the wires

Finished with Stainless Hardware

The final product

In the next installment, I'll focus on mounting the gauge and the O2 sensor bung.