Here is another diagram supplied by MotoCrossGear.com.  Even though we only work on engines, driving or riding is a huge component in making our engines look great.  If you are a karter, please do not try to hang your leg out when entering a corner, it doesn’t work.

In our last SwedeTech’s Corner, we started the troubleshooting guide for clutch kart engines, addressing no sign of spark and engines that may be starving for fuel. In this edition we will continue the guide. Next month’s SwedeTech Corner will go into troubleshooting Shifter Engines. So enough rambling, let’s continue.

Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light. This can be done by removing the spark plug and looking inside the cylinder with the inspection light. Look for any damage on the piston or cylinder walls. If you see damage, do not run and consult your engine builder. You will see this statement many times in this troubleshooting guide. This should always be the first step in any engine troubleshooting. I’ve seen countless engines that had a huge parts failure or a seized top end, and the mechanic just kept cranking the engine over without looking inside to see if the engine was even functional.

Engine Performs as if it is Flooded

• Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light. This can be done by removing the spark plug and looking inside the cylinder with the inspection light. Look for any damage on the piston or cylinder walls. If you see damage, do not run and consult your engine builder.
• Double check your baseline carburetor settings. If you are using a pumper style carb with tunable needles, remove the needles and look for damaged needle tips. Before removing the needle, mark each needle’s position and keep track of how many turns out each needle is by turning the needle all the way in until it closes while counting the turns. When you replace the needle, turn it all the way in until it stops and then open it back up to its former position.
• Make sure the fuel tank has proper venting to the atmosphere. If you are using a catch tank on the vent line, make sure the catch tank is properly vented. On most karting applications, supply, return, and venting fuel line connections with an I.D. of 3/16″ (4.8mm) should be adequate for proper fuel supply and venting. Always inspect all fuel line connections, especially on the inside of the plastic tank connections. Any obstruction inside the fuel line or connections will cause fuel supply issues.
• Always run a fuel filter inline before the carburetor and/or fuel pumps. If you think a fuel filter is causing a restriction, find a better one that will not cause a fuel restriction. Carburetors do not perform properly when they are filled with debris.
• Check the fuel inlet needle and seat for damage or debris. This can be done visually by removing the needle. If you feel the needle and seat are fine, check the pop off. When in doubt, rebuild it with the proper parts.
• Remove the carburetor and intake manifold and inspect the reeds for damage. Cracks, frays, and missing pieces will affect how the engine performs. Inspect the reed cage and the rubber coating for any damage or debris. If it is questionable, replace.
• Inspect the exhaust system for clogged exhaust cores or excessive carbon build up. If the end caps are removable, remove them and inspect the inside of the pipe. Before cleaning any exhaust component, reference your rules for modifications. Some rules do not allow any machining or porting on certain parts. We’ve seen a number of parts that were expensive paper weights because the previous user got carried away with a clean up tool or sanding roll.
• If you are using an air filter, do not oil the filter before a tuning session or track session. Adding oil to many filters will restrict the air flow, causing the engine to run rich. When possible, try to use a stiff filter that will not collapse under the suction of the engine’s intake stroke.
• Check the exhaust system for a forgotten or lost shop rag, usually blue or red in color. The tell tale sign of a rag in the exhaust, engine runs on the stand and sometimes idles fine. Once you are applying a load to the engine, it hesitates and stutters. It sits for a second and you can fire it right up, only to repeat the process. Don’t tell your friends when you find the problem, only tell them it was a bad spark plug.
• Check for any loose or bad electrical connections. Sometimes when the ignition system starts to fail, the engine can start to run rich. It can also start burning holes in the middle of the piston.
• Double check your fuel and if you are questioning the oil mixture or quality, replace the fuel and oil and remix.

Engine Lacks Acceleration and Top End Power

• Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light. This can be done by removing the spark plug and looking inside the cylinder with the inspection light. Look for any damage on the piston or cylinder walls. If you see damage, do not run and consult your engine builder.
• Double check all electrical connections. Refer to the electrical spark section outlined above. Electrical problems can hinder engines performance under a load without completely failing.
• Check your carburetor settings and compare to your baseline notes. Typically, if the engine will run to the higher rpm range, but feels lazy and lacking torque, the tuning can be lean on the full throttle position. If the engine labors and will not achieve high rpm’s, this can be a sign of a rich condition.
• Check your chain tension and condition of the chain. If the chain is tight, it will hinder acceleration and performance. If the chain is discolored from heat or has tight spots, replace. At the same time, inspect engine sprocket and axle sprocket.
• Remove chain and water pump pulley belts and spin the rear axle. If there is noticeable drag, inspect the brake rotor, brake pads, axle bearings, and axle bearing cassettes. Your engine is a work horse, the greater the load or resistance, the harder it is for the engine to achieve maximum performance.
• Inspect the exhaust side of the piston skirt. Do you see excessive “blow by” under the ring land. If the piston skirts look heavily worn or you see excessive exhaust discoloration below the ring, it may be time for top end service.

This guide was created to help you, but it is only a guide. There are many factors that we did not include that can also contribute to poor engine performance. When diagnosing a problem, you need to look at all factors. If the engine performs poorly in only one section of the track, try to think about other influences, not just the engine. You will also want to consider the following while troubleshooting:

• How is your chassis handling? (For more on how this relates to engine performance, refer to the Stable or Free – Which is Faster? article elsewhere in this issue)
• How is your driving affecting the chassis and engine?
• What did you recently change that may have caused a problem? (For instance, many times putting new tires on will over-stick the kart and actually hinder acceleration as opposed to improving it. See Tuning with Tires – FKI December 2010)
• When was the last time you performed a thorough inspection of all chassis and engine parts?
• Are other participants having the same problems?

Trouble Shooting Guide for Clutch Kart Engines

Working at SwedeTech and answering the customer technical questions, I’ve been able to compile quite a list of troubleshooting tips.  Most of the knowledge comes from direct hands on experience from the three of us in the shop.  Feedback from customers also allows me to stay current with the engines that are used in karting throughout the world.

The information in this article will hopefully help you when the time arises.  For all of us that have spent any amount of time at the track, some of these problems will sound familiar.  This guide is created with a clutch or direct drive engine utilizing a pumper style carburetor in mind.  So, I will quit blabbering with ‘fill content’ and get started.

Engine Does Not Show Spark

- Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light.  This can be done by removing the spark plug and looking inside the cylinder with the inspection light.  Look for any damage on the piston or cylinder walls.  If you see damage, do not run and consult your engine builder, preferably SwedeTech.

- Replace the spark plug and set the gap to the engine builders recommended specification.

- Check that the spark plug cap is snug fitting on the spark plug.  You should feel resistance of the rubber gripping the spark plug as you lift on and off.  If you see black graphite looking material on the porcelain, replace the plug cap.  This is caused when the cap is ‘floating’ up and down on the spark plug.  On most engines, the spark plug cap is screwed onto the spark plug wire.  Some other plug caps use a pin that pierces the plug wire and the conductor.

- Make sure your plug cap is properly connected to the plug wire.  To do this, hold the plug wire firmly and give the spark plug cap a solid pull.   The cap should not come off with a snug pull.  If it does come off, inspect the end of the plug wire and look for burnt or frayed conductor wire.  Cut off approximately ¼” of the plug wire and install the plug cap.  If the plug cap feels tight on the plug wire insulator, you can apply a small amount of WD-40 to help minimize the resistance while screwing on.  The WD40 will absorb and will provide a secure connection.

- Check all wire connections on the coil, stator plate, and all other wire harness items.  Look for cut, burnt or pinched wire insulation.  Unplug all wire connections and inspect the connection points.

- Look for any damage on the coil, stator, or flywheel.  Some ignition systems will fail to work if the stator or pick up unit takes a direct hit from track debris or an object.

- Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light.  This can be done by removing the spark plug and looking inside the cylinder with the inspection light.  Look for any damage on the piston or cylinder walls.  If you see damage, do not run and consult your engine builder.  You will frequently see this statement in this guide.

Engine Performs As If It Starving for Fuel

- Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light.  This can be done by removing the spark plug and looking inside the cylinder with the inspection light.  Look for any damage on the piston or cylinder walls.  If you see damage, do not run and consult your engine builder.

- Make sure the fuel tank has proper venting to the atmosphere.  If you are using a catch tank on the vent line, make sure the catch tank is properly vented.  On most karting applications, supply, return, and venting fuel line connections with an I.D. of 3/16” (4.8mm) should be adequate for proper fuel supply and venting.  Always inspect all fuel line connections, especially on the inside of the plastic tank connections.  Any obstruction inside the fuel line or connections will cause fuel supply issues.

- Always run a fuel filter inline before the carburetor and/or fuel pumps.  If you think a fuel filter is causing a restriction, find a better one that will not cause a fuel restriction.  Carburetors do not perform properly when they are filled with debris.

- Inspect fuel lines for holes, debris, pinched or restricted bends, and overly tightened zip ties.  If you are using zip ties to secure the fuel line, remove them and use hose clamps or safety wire that is wrapped twice around the line before you tighten.  Zip ties will cause the hose to unevenly secure the fitting, and in some cases will cause an air leak.  The zip tie does not form a full circle with such small diameter tubing.  The fuel line should never have kinks or pinches in them.  Make sure all suction side of fuels lines are secured with safety wire or hose clamps.  Sometimes the damage on the fuel line can be noticed if you flex and move the line around.

- Inspect carburetor gaskets for damage or wear.  Inspect filter screen for any debris, even the smallest pieces of lint.  Inspect carburetor hard parts for cracks or damage.

- Check the carburetors pop off pressure and the fulcrum arm height.  These specifications will vary from each engine builder, so consult with them for the proper numbers.

- Check the gasket between the carburetor and intake manifold/cylinder.  Make sure the pulse circuit is unobstructed with a gasket or misalignment.  Check the pulse line for obstruction, damage, cuts, or loose fittings.

- Before trying to restart the engine, always inspect the inside of the engine utilizing an inspection light.  This can be done by removing the spark plug and looking inside the cylinder with the inspection light.  Look for any damage on the piston or cylinder walls.  If you see damage, do not run and consult your engine builder.

As a subscriber to Firestone Karting Info, you thirst for more knowledge, you are very hands on, and you want to have an edge over your competition.  Karting should be about drivers or families working on their own equipment, as it is the grassroots bastard child of racing that receives little respect from those that leave us hardcore karters behind.  It is the simplest form of motorsports and a very cost effective way to feel the sensation of high speed cornering and head tilting acceleration (if your kart has a Swedetech engine).

On that note, I am not going to highlight one particular engine package this month, but the complete karting package as a whole.  In my opinion, one of the most overlooked resources easily available to karters is the rule book and/or technical regulations available from every major karting series.

Organizations spend hundreds of hours compiling rules and regulations to keep the racers safe, to keep costs under control, and to bring standards to our favorite motorsport.  As the main contact person at SwedeTech, I field most of the phone calls and emails.  I have the general attitude that no question is stupid.  I am constantly communicating with the owner and our technician about engine related technical inquiries.  This is how we learn.  Every year when the new rule books come out, I order them for the shop and read through the various sections that relate to our engines and customers.  Every time I go through the rulebook, I learn something more.  For this article I grabbed three of our most referenced rulebooks.  It is about a 3” pile of paper, filled with technical jargon, diagrams, numbers, and a lot of dots.

If you are racing in a series, YOU NEED TO HAVE A RULEBOOK for that series.  If there is any technical question, race event format, point structure, chassis requirements, engine specifications, etc, it will be in this book.  It is even a rule in most rulebooks that you need a rule book with you at the race event.  I was participating in an event years ago for a local IKF regional series.  Ron Emmick was the tech guy and his post race technical procedure was to bring your rulebook to tech.  I’ve never seen so many racers running around like idiots trying to beg, borrow, or steal a rulebook so they would pass tech.  The best part was Ron marked each book, so you could not share with a competitor.  I thought it was brilliant.

The rule book should be the first publication that you read at the beginning of each year.  For example, that new rear plastic bumper you purchased for your chassis has a minimum distance front the bumper to the rear tires.  It also has a maximum dimension.  It would suck to get disqualified because you mounted the bumper with flat stock and zip ties, then wrapped the zip ties in electrical tape, only to find out it was not within the proper specifications for mounting or within the legal dimension.

What about checking the head volume in your engine?  If you don’t know how, don’t call the local kart shop or engine builder, grab the rulebook and read the technical procedures.  Many of the rulebooks will explain the CC process as well as many other technical procedures.

I know that it is much easier to call the local shop, or just the first one that happens to answer the phone.  You may ask them a question and receive the proper answer.  But what if you call that same shop and they misunderstand your question, they don’t know which series you are racing, or you cannot explain to them the exact technical question that you have.

For example, a few years ago there were about 4 sets of Stock Honda rules floating around.  Depending on the part of the country you were in, it could make a big difference on the technical regulations.  One series called out for stock, OEM direct replacement reeds.  Another series specified a range of model years that were legal for the Stock Moto.  One series allow for open reeds, but did not allow for reed stiffeners.  At that time, if you didn’t know the rules and you ordered reeds online from SwedeTech, there could have been a good chance that your reeds were not legal.

If you want the proper answer, you need to do the research.  I have found many times that someone will call and ask a tech question on something they should know.  If you are racing any series, as a competitor it is your responsibility to know and understand the rules.

Do a little exercise right now.  Grab your current rulebook for the series you are racing in next.  Randomly open the book to any page.  Read those two pages and ask yourself if you learned anything new.  If the answer is yes, think about how much information is contained in the other 136 pages.

As an engine shop, our noses are constantly buried in the rule book.  At the end of a race, what is the most common item that is scrutinized?  It is not the driver or the chassis, it is the engine.  If we make a mistake, our customers are greatly affected.  We have a great reputation for quality and our service, and a huge reason is because we know and understand the rulebook.  You can better play the game if you know the rules.

Years ago I worked for a kart shop that started an in house engine blueprints service.  They hired an “engine builder”, purchased a dyno, stocked the shelves with engine parts, etc.  There was one HUGE problem.  The engine builder didn’t understand the rulebook.  There was one particular engine that he spent many hours and even more dollars on developing.  He had swapped the OEM ignition for an aftermarket one.  One big problem, the rules specified that the ignition stator and flywheel assembly must be OEM.  Dollars and hours were wasted by this company because an employee did not understand the rulebook.

I field many questions on a daily basis that are easily answered in the rule book.  I have seen people disqualified from events because they didn’t understand the rules.  My job is to help people, but it is your responsibility to arm yourself with the proper knowledge.  In many cases, this knowledge is very easy to access if you take the time to read it.

So before you decide to build a custom fairing, or machine the head on your stock Honda, or run a 1.5mm thin walled axle, or run a fuel pump driven off the axle, or any other creative idea that might strike you at 3am in the morning, read your rulebook.

And in closing, how did that earlier exercise work for you?  Did you learn something new?