It was the WERA 24-Hour endurance race at Willow Springs in 2000, and the Middleweight Superbike Championship points battle was raging between Army of Darkness and Paramount Racing. Both teams had survived the scorching heat of the relentless September-afternoon desert sun and were running strong into the evening. At 9:00 p.m. the AOD bike began losing power at the top of the rpm range. The 2000 Suzuki valve retainer gremlin had struck and Sam Fleming pulled into the pits with the telltale sounds of a broken valve retainer dancing around the top end.

We set about changing the engine under the green flag, everyone going about their individual tasks carefully and deliberately as we all took turns chanting the green-flag-motor-swap mantra: Don’t rush, just do it right. Don’t rush, just do it right.

Nolan gets in a few reps with a discarded GSX-R motor in the middle of the 2000 24-hour race. The 600cc motor was supposed to be rebuilt after this race so someone had magic markered “750” on it in the hopes that a protest would finance the post race tear down. Photo – Brian J Nelson

Our motor swap took about 45 minutes and we re-entered the race way behind Paramount and with no real hope of catching them on the track. Through the night and into the next morning the bikes kept circulating and the riders kept swapping and the pit crew changed tire-after-tire while we counted down the hours. But Paramount was also running a 2000 GSX-R600, and sometime in the morning their bike started making the same noise. They pulled in for a new engine, and we were back in the game.

Their engine swap took less time than ours, but apparently they did not have the power of our mantra in their pits and something wasn’t done right. Soon after leaving the pits they were back in again for more work, and we passed them for the lead and widened the Championship points gap. Another 30 minutes later their bike was off on the side of the track with something improperly connected while their rider sat on the retaining wall, watching us finish the race.

With a mid race engine transplant the AOD bike lived to see the dawn. Photo Brian J Nelson

So here you are, installing a freshly-built engine into your chassis, getting ready for the race season to start. You’re not under the green flag, and you have the time to make sure everything is done right. So do it right.

While you can install an engine into a frame by yourself, it’s easier if you have at least one person help you. If you are solo you can either leave the engine on the floor and lower the frame onto it, or balance it carefully on a jack and raise it up to the frame. Most 600s, including the Yamaha YZF-R6, have two long rear motor-mount bolts that are installed first; once those bolts are installed, you can let the engine hang from them while you line up the front motor-mount bolts to position the engine correctly. As always, follow the steps outlined in the service manual for the motor-mount installation sequence.

The torque wrench is your friend. Whether you use a beam-type or click-type torque wrench, the most important thing is to use a torque wrench, and don’t get ahead of yourself. It can be very tempting to set the engine in place and then start plugging wires together, but just like all of the other little jobs you’re starting and finishing in order to get your bike ready for the track — don’t give in to that temptation. Make sure you tighten all of the motor mount bolts in the proper order and to spec as dictated by the service manual before you move on to the next task.

The torque wrench is your friend. Whether you use a beam type or click type torque wrench, the most important thing is to use a torque wrench, and don't get ahead of yourself. It can be very tempting to set the motor in place and then start plugging wires together, but just like all of the other little jobs you're starting and finishing in order to get your bike ready for the track -- don't give in to that temptation. Make sure you tighten all of your motor mount bolts in the proper order and to spec as dictated by your service manual before you move on to the next task.

An installed engine with no oil in it is a disaster waiting to happen. If the key to your bike is in the ignition, pull it out. Tear off a large piece of duct tape, preferably red for DANGER!, place it over the ignition switch and write NO OIL on it. If your bike doesn’t have an ignition switch, turn the kill switch to the off position and put the tape over it.

Okay, now go after the wiring-harness plugs. Some of these wires mate with plugs from the airbox, throttle bodies, or gas tank/fuel pump but the ones you can plug in or attach after the engine is installed generally are:

1. oil pressure/level

2. gear position

3. alternator

4. pickup generator

5. battery ground

6. starter lead (battery positive from starter relay)

At this point you can also attach the spark plug leads.

Tape off any electrical leads you are not using (fan, horn, speedo drive) to keep them clean for future use if the bike is returned to street service and to prevent electrical confusion at a later date when hooking up a wiring harness.

If your bike comes with a heat shield between the engine and fuel system, now is the time to put it on. The foil side faces the engine to reflect the heat back down and away from the throttle bodies and fuel tank. After installing the heat shield you can slide the intake boot clamps on over the intake boots. Be careful not to drop anything down the intake ports while messing around there. We usually duct-tape over the intake ports but in the nearby photo the ports are blocked with paper towels.

With the engine installed and everything tightened and plugged in, you can turn your attention to drilling the exhaust nuts for safety wire in preparation for installing the exhaust system.

If you’re a disciple of the less-weight-and-more-power-is-better doctrine, you probably bought a race exhaust system, in which case some assembly is required. Because of the extreme heat involved, exhaust parts have a propensity for corroding and/or welding themselves together. To discourage this tendency, apply a little anti-seize to the mating surfaces on the headers, intermediate pipe, and exhaust canister. NOTB runs Graves pipes, AOD runs M4.

After you’ve loosely bolted on the headers and smeared anti-seize all over the place, attach the intermediate pipe(s) with the springs that should have come with the exhaust system. A spring tool is indispensable for this job.

Just hook one end of the spring onto one tab on the header and use the spring tool to stretch the spring and hook the other end to the corresponding tab on the intermediate pipe. Using this tool generally prevents a lot of knuckle-busting, bleeding and cursing so if you’re in it to vent your anger you probably don’t want to use it.

Once you’ve got the exhaust head pipes and intermediate pipe connected, install the canister and mount it loosely. If you are using the stock mounting hardware, carefully check the mounting position to ensure that the canister won’t stick out too far or hang too low and interfere with cornering clearance. In the example shown, we ended up not using the stock mount for this reason.

The custom muffler hanger seen on page 100 was built using aero tear-drop-shaped hollow steel tubing usually found in aircraft applications. Although lightly discolored, it is very sturdy and very light. Including the time it took to fabricate two muffler hangers this piece would probably retail right around $150.

An exhaust leak at the headers can sound like terrifying internal top end noise, as well as causing an engine to run lean. One of the best ways to avoid discovering this for yourself it to tighten the header bolts (or nuts) after you’ve got the whole exhaust system lined up the way you want it mounted, and then safety-wire them.

The radiator probably ranks up there with wheel and suspension bearings as one of the most commonly neglected parts on a racebike. It’s easy to ignore the build-up of little rubber chunks off the front tire or the dented and bent fins that are the result of rocks and other detritus flung up by your bike’s front wheel or the rear wheel of the bike ahead of you and slamming into your radiator. That stuff builds up and can hurt the cooling efficiency of the radiator. We’ve found the best way to deal with this is with an ounce of radiator screen at the beginning of the year instead of a pound of new radiator at the end. With a bit of aluminum wire mesh (part #9227T425 from McMaster-Carr, www.mcmaster.com), a few zip-ties, a pair of diagonal cutters and some plastic tubing you can build a radiator screen that will prevent most of the rubber and earth missiles from damaging the radiator.

First, trim the screen down to fit the radiator. Make it wide enough so it will cover the full area of the radiator but not so wide that it will bow in and touch the fins. Allow a little bit of room on each side for the plastic tubing. When you’ve got the screen sized, fold the ends of the vertical wires over the last horizontal wire at the top and bottom of the screen to prevent the screen from unraveling. Then do the same with the sides.

Next, cut two pieces of plastic tubing to match the height of the screen. Slice the tubes open on one side down their entire length and slip the tubes over each side of the screen. Attach the tubes to the screen with a few zip-ties, being careful to face the locking part of the zip-ties away from the radiator side.

Most radiators have a margin on either side where you can safely mount the tubing with zip-ties. In the picture on page 102 the zip-ties holding the screen onto the radiator have been fed through this margin, not through the fins. Your finished product should look something like this. If the screen bows in and rubs on the fins you may want to detach it and trim down one side a little. If the screen is stretched tight and pulls too far away from the radiator you run the risk of contact with the front tire when the suspension compresses and you may want to start over with a new piece of screen and make it a little wider.

Installed.

The slight curve in a properly-installed radiator screen will help keep it away from the front tire, out of harm’s way. We have noticed no loss of cooling efficiency due to installation of these screens and have enjoyed longer radiator life because of them.

With the radiator mounted and all of the various hoses hooked up and tightened, you’re ready to add oil and water and spin the engine over.

First, the oil. If you don’t already have a new oil filter installed, now’s the time to do it. Spin off the old filter using an oil filter wrench. Smear a little oil around the sealing surface of the new filter, fill it with oil and spin it on. There are a few theories as to how to tighten a new oil filter. You could refer to the service manual and tighten it to spec. The other methods we’ve used are: Spin the oil filter on until it seats and then tighten it another quarter-to-half-a-turn using the oil filter wrench; or, tighten the oil filter as tight as you can get it by hand, using no tools.

Once you are satisfied the oil filter is properly tightened, place an appropriately-sized hose clamp over the filter and tighten it. If there is a boss or bracket or something on the engine you can back the screw housing of the hose clamp up to so that the hose clamp will prevent the oil filter from unscrewing, use it. If not, you’ll need to safety-wire the hose clamp to make sure the oil filter can’t loosen. Unfortunately the clamp is not going to prevent the oil filter from simply blowing off if too few threads mate to the boss due to the installation of the wrong model filter or, as with Fram filters for a while, the manufacturer of the oil filter made a mistake and didn’t build enough threads into the filter. If the filter doesn’t turn five-to-10 times before it tightens up, you should double-check the appropriateness of the installation.

Check the engine drain bolt for tightness, and safety-wire it. Then add oil up to the fill mark on the engine, whether it be indicated by a mark on a sight window or on a dipstick.

For the radiator, used distilled water. Although most forbid coolant in racebikes, most organizations do allow Water Wetter (available at most motorcycle shops or online) which you can mix with the distilled water to help prevent corrosion in the cooling system. Water Wetter does not prevent freezing, however, so you’ll have to drain the cooling system any time the temperature drops below freezing. It’s also mixed at a different ratio than coolant so you’ll have to check the bottle for mixing instructions. You can also use just straight distilled water if you prefer.

Pour the water mixture slowly into the radiator until the radiator is full. Then, massage the coolant hoses to work the air out of them. Refill the radiator and repeat until you’ve worked out all the air bubbles and the water level in the radiator doesn’t drop anymore. Some bikes have bleeders attached at various high spots on the cooling system to let out bubbles (Hondas are famous for this) so check your model’s service manual carefully for any coolant system bleeding instructions. Make sure the gasket on the radiator cap and the filler neck of the radiator are squeaky clean. Any flotsam in there will reduce the pressure the cooling system can hold, causing the system to boil at a lower temperature—definitely not a good thing in Texas in August. Attach the radiator cap and safety-wire it. Make sure you have added water to the overflow bottle. Even after massaging the coolant lines and rocking the bike around a bit there probably will still be bubbles in the system. Most cooling systems will purge this air to the coolant overflow bottle and suck water back in as the system cools. Make sure you have the small line from the radiator going to the bottom of a coolant overflow tank and the vent line (at the top) of the coolant overflow tank vented to air. We usually point this vent line at the rider’s foot so the rider will notice if the engine is overheating before the water gets onto the rear tire.

Now you’re ready to spin the engine over to achieve oil pressure. If the engine won’t turn over without the fuel pump hooked up, you’ll have to connect the fuel pump and take other measures to ensure that your bike won’t start, such as removing the spark plugs or disconnecting the plug caps.

Hold the starter button down for a few seconds to spin the engine over and get the oil moving through it. Cycle the starter a few times until the oil pressure light goes out. Remove the radiator cap and top off the radiator as needed if turning the engine over released any air trapped in the cooling system.

If you’re running a bike with carburetors and are re-jetting for exhaust/air filter/engine modifications, you will obviously want to do that before you install the carbs. Ditto for any mods you are making to throttle bodies if you’re running fuel injection, such as slide stops. Because this is the 21st century we will simply reference throttle bodies for the sake of this article.

Make sure the intake clamps are on loosely and there’s nothing blocking the intake ports, and push the throttle bodies firmly into the intake boots until they are fully seated. Tighten the intake clamps, and then attach any relevant plugs (throttle position sensor, cylinder temperature sensor, etc.). If you have a cable-activated fast-idle adjuster, route that to its mounting point and attach it.

Attach the throttle cables and mount the pull cable onto the throttle body bracket to allow some freeplay adjustment at the throttle housing (i.e., don’t pull all of the slack out of it). Be sure to lock the locknuts on the cables to secure them to the bracket as it really sucks to have one of those locknuts wedge the throttle open. You can do the final freeplay adjustment at the throttle housing with the bike running to ensure you have just enough freeplay but not so little that the throttle will open when you turn the bars all the way to the right.

Next, set the airbox on top of the throttle bodies and plug in any pertinent hoses like those for the PAIR valve or crankcase breather. Sometimes it’s easier to attach the hoses before you have the airbox bolted on. Check for any electrical plugs that need plugging in and attach if applicable. Line up the ram-air ducts (if applicable) and then push the airbox down onto the throttle bodies until the boots are seated. Tighten all clamps and bolt the airbox down.

You can use the stock air filter, especially if it is a reusable foam type air filter, or you can use an aftermarket foam or oiled-pleated-fabric air filter. Most aftermarket filters are generally reusable and less restrictive than a paper-element stock filter, which will give you a slight performance advantage but may sacrifice some engine life since they do not filter as well as a stock filter. Since this is a track bike it is very unlikely that you will ever run into a problem with cylinder wall wear due to fine particulate making it through the air filter. It’s usually easy enough to change out the filter with the airbox installed.