Cooling System Filling
Turning Polyurethane Suspension Bushes
Measuring Engine Mount Positions
Measuring Engine Mounts From Photos
Removing Stubborn Bearings From Engine Cases
Replacing Front Wheel Bearing Grease With Oil
Setting Up an Hydraulic Bike Clutch Pedal
 

Cooling System Filling

Mix slightly more coolant and water (50/50) than your cooling system holds and with the engine cold, fill the radiator/header tank. Keep an eye on the level for a minute and replenish as the coolant is drawn into the system.

Once the level stabilizes, start the engine, but leave the radiator cap off and run the engine until the fan switches on three times, then switch off.
Let the engine cool with the cap off, then top up the radiator/header tank to the "max" mark. Put the cap back on, and re-start the engine.

Run the engine again until the fan switches on three times, then switch off and let the engine cool down.

The coolant should have returned to the max level, but if it's below the mark, then top up to the mark again and check for leaks.

Turning Polyurethane Suspension Bushes

Polyurethane can be tricky to turn because it resists cutting and deforms away from the tooling. Turning it at a 2:1 diameter to length ratio (Ø50mm of rod protruding 100mm out of the chuck) helps it retain its shape.

PU will melt at approximately 228°C (550°F), so  well maintained sharp points of 90° to 110° will help prevent heat build up. For best results turn the rod at approximately 15,250 cm/min [500 ft/min].

When drilling the bores of the bushes, force the drill bit through the rod and quickly retract it again to clear the debris. Reinsert the drill bit but allow it to dwell briefly which will actually melt the PU to the correct diameter!

All in all, it's a lot simpler to turn PU straight from the freezer. At a temperature of -17°C (0°F) it machines quite well and a fine finish can be achieved.
Aim for a sliding fit which will result in a perfect interference fit when the polymer returns to room temperature.
 

Measuring Engine Mount Positions

Make up plugs on the lathe to accurately fit the mounting holes in the engine's casings. The plugs should have a shoulder or flange to help locate them in the holes. The faces of the plugs should be flat and have a shallow pointed hole drilled in them, just enough to locate the legs of your dividers.

Using the dividers, measure in pairs, the centre to centre distances of all the holes/plugs and either make a CAD drawing or paper layout from their intersecting arcs. If you've made decent plugs (keeping their ends in a common plane) and measure carefully, the results will be good enough to construct the chassis mounts from (they are probably likely to be welded on and will pull slightly as they cool anyway). 

Use numerous pairs of arcs to confirm the mounting hole positions from as many different pairs of plugs as possible and stay in plane to eliminate third axis trigonometric errors.
 

Measuring Engine Mounts From Photos 

Taking measurements from a photo can be problematic and really needs proper software to digitize the image which will have at least some parallax errors and will need to be scaled before any of the data can be used. 

At the very least, mount the camera on a tripod or box and place the camera (preferably digital) as far as possible from the engine. A close up will have too much spherical aberration to be accurate. Since you don't need good resolution, it won't matter if you have to blow the picture up, just as long as the area you want is in the middle of the image.
Make sure the camera is square on to the engine and the lens height should be as close to the mid height of the engine as possible.

Removing Stubborn Bearings From Engine Cases

In most instances, bearings will virtually fall out of a case if it is through heated to around 175°-200°C [350°-400°F] in an oven (or carefully with an oxy torch).

Inevitably, you'll come across one that refuses to budge and it's usually the one that's in a blind hole and can't be pressed out! 

An implausible but incredibly effective method of removing a bearing from a blind hole is to pack the hole behind the bearing full of grease and then insert the shaft (or another of similar diameter) into the hole.
You then give the shaft a couple of good whacks with a heavy mallet and the resulting hydraulic pressure from the grease will force the bearing out of the blind hole!
Be sure to wear goggles as the grease can spurt out through the bearing.
 

Replacing Front Wheel Bearing Grease With Oil 

Although this creates extra work, it does reduce drag considerably. As the cars are so light, there is no detrimental effect on the life of the bearings.

The inner bearings' inner seals and both the outer bearings' seals must be carefully removed  using a small screwdriver or other pointy tool.

You will also need to modify the dust caps on the outside of the hubs by drilling a Ø12mm filler hole in the centre of each and fitting them with rubber grommets.

With the front hubs installed, remove each of the rubber grommets, and fill with 10WT gear oil until it reaches the level of the holes in the caps.
You should check the oil level periodically.

Setting Up an Hydraulic Bike Clutch Pedal 

When using the stock bike slave cylinder with a Girling type master cylinder (normally Ø.625"), it is possible to push the pedal too far, causing damage to the clutch.

Fitting a pedal stop (applies to a cable operated clutch too) is an obvious solution and ascertaining where the stop should be is fairly simple.

Adjusting the pedal stop should be carried out with the rear of the buggy securely raised on stands. While idling in first gear, lightly drag the brakes and push the clutch in slowly. The point where the wheels stop rotating is the position where the clutch pedal stop should be - plus a quarter turn. Much further and damage could occur.