Happens in the Tech Shed?
Part I - 2 Cycle Tech
Here is a quick glossary of some terms rookies may not be familiar with;
Cc's: Cubic Centimeters - The volume of an engine's combustion chamber when the piston is at top-dead-center (see TDC below). The allowable minimum number of cc's in the combustion chamber is one method of controlling compression ratio. The greater the cc's, the lower the compression ratio, thus lower power. Fewer cc's mean less compression, and less performance. In general, engine builders will try to get as close to the minimum legal cc's without failing tech. It is important to allow a little extra room in there to compensate for any carbon buildup during the race.
Top-Dead-Center (TDC): The point in the crankshaft rotation where the piston is at its maximum up position in the cylinder. This is the starting point, zero degrees of crank rotation, for all measurements of port heights, cc's, and stroke length.
Ports: These are the holes in the walls of the cylinder that allow fuel/air mixture into the cylinder and burned mixture out. Their location and sizes are critical to proper performance and these items are rigidly controlled by the tech rules. As the piston moves down in the cylinder from top-dead-center it uncovers (and thereby opens) the exhaust ports first, then covers (and thereby closes) the intake port, and finally opens the transfer ports. Sometime when you have nothing else to do, take the carb and the head off your engine and take a look down the cylinder. Then slowly turn the engine over by hand and watch the sequencing of the port openings and closings.
Venturi: This is the narrowest part of the air passage in the carburetor. As the air rushes into the engine through the carb, the narrower opening in the venturi makes the air move faster and this helps it draw fuel from the carb into the airstream going into the engine. Moreover, the overall size of the venturi opening determines how much air your engine can "breathe" and, therefore, how much power it can produce. A bigger venturi allows more airflow and increases performance. That is why venturi size is an important tech item.
Karting is based, philosophically, on affordable, fair competition. Over the years, rule makers have labored long and hard to maintain a "level field" for all competitors. There are detailed rules for chassis, bodywork, tires, etc., all designed to encourage good racing without anyone having an unfair edge. Success should come to those who prepare and tune their karts with the greatest precision, and then drive them with the greatest skill. Of course, many of the chassis, bodywork, and other rules are also major safety considerations, and these are usually addressed at prerace tech inspection. But issues of whether or not the fuel, engines, and related components conform to specifications, or whether or not they may have been modified or tampered with beyond the allowance of the rules is a matter for
post-race tech inspection. Because all of us want to find ourselves in the winner's circle someday, it is important to understand the nature of the tech inspection procedure and what to expect.
2 CYCLE TECH
Most tech officials prefer to do fuel tech before they tear into an engine, for a couple of reasons. First of all, there is no reason to go through all the trouble of teching an engine if the fuel will not pass. For the last several years, fuel tech has consisted primarily of checking with the Digatron fuel meter. Properly used, the Digatron is still a valid way to screen competitor's fuel. But more and more tracks and clubs are using additional tests to discourage the use of dangerous fuel additives. Most common among these is the Spot Test for Dioxane in Gasoline, commonly called the Germaine Test or the "Snowflake Test". This test involves taking a small sample of the racers fuel, preferably from the fuel line to the curb, and placing it in a tiny test tube. Then a drop of the test chemical is added from the top. It is normal for a drop of engine oil to come out of the solution in the fuel and drop to the bottom of the test tube. This is not an indication of something illegal in your fuel. What the tech man is looking for is the formation of little white or light gray "snowflakes" in the fuel that drift down to the bottom. If these these "snowflakes" occur, it is an indication that there is a chemical called 1,4 Dioxane in the fuel. That is illegal, and very dangerous. 1,4 Dioxane never is a component in gasoline from the refinery. If it is present, it is because someone added it. There are some commercially available additives that contain 1,4 Dioxane, as well as some pre-packaged, premixed fuels. If you have any doubt about the legality of your fuel, ask the supplier, your kart shop, or call the manufacturer. Most good tech men will also happily test your fuel for you before racing begins at the track. Just try to be sensitive to the timing. Showing up with your fuel sample to be tested just before a big class comes off the track for tech is bad manners and will not get you on the tech man's good side. Remember, regardless of what tests are being done, it is critical that the tech man be careful that nothing contaminates a competitor's fuel or fuel sample or, for that matter, the calibration standard. Other tests may, at the discretion of the organizers, be done on a routine basis. The point is, as long as the tests are properly performed, and uniformly administered, and as long as they do not violate the rules, they are fair.
Once fuel tech is completed, the tech inspector is faced with a bewildering array of engine specifications to check. While it is certainly within the tech man's authority to measure each and every dimension called out in the tech book, that sort of exhaustive examination could take hours. Instead, most tech inspectors select a few significant items from the laundry list of possible tech items, and check just them. If a racer is running a Yamaha or other Piston-Ported engine, or a 100cc or 135cc Controlled Stock class, the most common thing to check is cc's (cubic centimeters) in the head. And since that needs to be checked with the engine assembled, it is usually the first item on the tech list. Since a hot engine will cause fluid inside of it to expand, a racer who thinks they might be close on cc's may want to let their engine cool some before the test is performed. However, it is up to the racer to tell the tech man when they think the engine is cool enough to cc'd. Of course, this test is within reason. The tech inspector has got a lot to do, so do not make his job any harder. Again, it is never a good idea to get on the tech man's bad side.
For racers who are running the Can muffler class, the tech official may elect to check those components while they are waiting for the engine to cool down. Here is an important point to remember: racers should wait for the tech man to tell them what parts he wants them to remove for inspection. It is a good idea to remove the sparkplug to speed up the cooling-down process, but they should leave everything else alone until the tech official tells them to take it off for him.
Beginning with the 2000 season, both IKF and WKA specified a new tech procedure for cc's, but it is still pretty straightforward. With the sparkplug removed, the tech inspector screws a specially machined insert into the sparkplug hole. This insert goes all the way to the bottom of the threads and extends up a corresponding amount. What it does is insure that the competitor's engine does not have some "creative" machining in the area of the sparkplug threads that let the engine pass tech with enough cc's with the sparkplug removed, but run with tighter cc's with the sparkplug installed. Anyway, whether the tech man is using the new fixture or not, he will then roll the piston up to TDC (top dead center), then just past TDC. Then, using an accurately calibrated measuring tube called a Burette, he will measure exactly the specified allowable number of cc's of fluid into the spark plug hole. Then he will slowly roll the piston back up to TDC. As long as no fluid spills out onto the flat surface, the engine is ok. It is not proper for the tech man to stop the piston at TDC and measure in the total amount of fluid required to fill the insert all the way to the top. If a racer has any doubt about how this test is to be properly done, they should carefully read that section of the tech manual.
Once the cc check is done, the tech man will probably ask the racer to remove the cylinder head and the carb. He may check bore and stroke, port heights and sizes, and the condition of the ports. After checking the port heights, he may ask that the cylinder also be removed to make it easier to check the port widths and to examine the "no-touch" areas of the ports for any tampering. There are a number of dimensions in the carb to be checked as well. Here is another important point. Dimensions that have a specified maximum size, whether in the carb, cylinder ports, exhaust can outlet holes, restrictors, or whatever, should be checked with a specially made dimensional tool called a no-go gauge. Each particular spec will have its own no-go gauge. If the spec calls for the carb venturi to be a certain size no-go (like 950 no-go for the Walbro carb on a Yamaha or Piston-Port), the tech man should gently test the venturi with the no-go gauge. As long as it does not pass into the venturi, it is ok.
The point is that these dimensions need to be checked with a proper no-go gauge, not with a vernier caliper or micrometer. It is not the tech man's job to determine what size these dimensions are, only that they do not exceed the maximum. Like the cc's in the head; it is not up the tech man to know how big (or small) the engine's cc's are, only that they exceed the minimum. Unfortunately, a few less honorable individuals have used their position as tech inspectors as a device to "spy" on what other, successful, engine builders are doing. This is not to be tolerated. If the tech man is getting too nosey, racers should ask him politely what he is checking and verify that it is according to the tech manual. If a racer is still not satisfied, then they should ask the inspector to stop until they can speak to the race director or other chief official.
In general, once the tech official has finished with fuel tech and whatever dimension and other checks he elects to do, it will be up to him as to whether the racer can take their kart and leave the tech area or if he wants them to stick around until he techs the other top finishers in your class. Again, in the interest of saving time, many tech inspectors now pick out only one or two of the top five finishers to tech, rather than going through all five. It is also common practice at some events for the tech inspector to ask the top finishers if they wish to waive tech. If the top finishers all agree that they are willing to waive tech, they assume that everybody is legal. In most cases you will not get any argument from the tech man; it is less work for him. But, even if the top finishers want to waive tech, it is still the tech man's call whether to look at the engines. Of course, if any of the top finishers do not agree to waive tech, then tech must be done.
One final thought: as a top finisher, tech is a racers right. Any racer has the right to prove that they earned their position fair and square and they have a right to be assured that the other top finishers are legal as well: Tracks and clubs that do not do tech undermine the credibility of their programs. A policy of not doing tech invites racers to break the rules and diminishes their respect for the track, the officials, and the entire event. If the track where a racer competes routinely does not do tech, they should be asked to do so. If they do not have anyone to do, it, a racer should study up and volunteer to be the tech man. If they still do not agree to do tech, my advice is to find somewhere else to race. If a racer is competing to measure yourself against other karters and their skills, lack of tech robs you of that opportunity. A racer cannot know if the guy that beat them was racing according to the same rules as they were. Every track should be required to run a fair and reasonable tech program. Same goes for pre-race tech. As a matter of your personal safety, racers want to make sure that every kart, including theirs, is in safe racing condition. In another article we will look at the importance of thorough pre-race tech inspection.
Next month we will look at the 4-cycle tech procedure and what racers should expect when it is their turn to face the tech man. See you then.