Dyno tuning: Consists of testing engines under varying conditions, such as part throttle or cruise to full throttle for maximum horsepower. There are many well made dynamometers on the market, but I'll try

to explain why you don't need to spend the big bucks to obtain more power and better driveability.

The majority of motorcycle/performance shops don't require the ability to create complete maps for fuel injected engines. These maps are supplied with the aftermarket fuel injection controllers that you install for your customer. Most of these maps are selected based on the type of exhaust system installed on the motorcycle and work quite well under cruising conditions as well as riding around town .  The inertia dynamometer becomes helpful when you need to alter the installed map for maximum HP and Torque or better driveability. The same holds true for engines with carburetors. 

Any experienced tuner will tell you that rpm and throttle position are what he needs to know when dyno tuning any engine for best performance.

Applying a load on the engine: The proper way to apply a slight load for tuning driveability problems such

as hesitation, stumbling or misfires is to run the vehicle in one of the upper gears at the rpm where the problem occurs; this is usually in the lower portion of the rpm range and almost always at less than 50% throttle position.   Then, slightly apply the rear brake while slowly opening the throttle to simulate  the condition where the problem seems to occur. During these tests the LM1 air/fuel analyzer should be used to record the air/fuel mixture, so the tuner can determine if the mixture is too rich or too lean when the problem occurs.  If this technique is done correctly, the rear brake will not overheat and will have minimal wear.

Fuel injected engine tuning: Today's fuel injected engines are easy to tune because all that is required is

a laptop and understanding how the software works. Once you are comfortable with the software of the controller you are using, you simply have to adjust the area of the map that needs attention. 

For Maximum Horsepower you may only need to change the air/fuel mixture and ignition timing in the 100%

column to the right of the map.  By using one of the upper gears and starting at low speed (30-40mph) you can open the throttle wide open and hold it open until the engine redline is reached. During this test the LM1 meter should be used to determine if more fuel or less fuel is needed. Most engines make good power in the area of 12:1 air/fuel ratio in the upper third of the powerband. After testing with the proper map for the exhaust system on the bike, the air/fuel mixture may only need to be changed slightly. This is where dyno tuning is essential for finding extra horsepower and torque.  When tuning for driveability, you simply load the engine in one of the upper gears while watching the laptop to see at what throttle position and rpm the problem occurs. Check the LM1 graph for proper mixture and adjust as needed to improve driveability.

Carbureted engine tuning: Understanding carburetors is critical here. Many tuners know that carbs don't know anything about engine rpms; they only know throttle opening position. The throttle opening position determines which circuit is being used to deliver the proper amount of fuel to match the air flow through the carburetor. But tuning is very similar to fuel injected engines, because many of the driveability problems occur in the idle to 50% throttle opening range. Just off of idle the idle mixture screw position, along with the pilot jet, slow speed jet and needle position can effect driveability up to the 50% opening. Above the 50% throttle opening to wide open throttle, the needle(s) and main jet(s) determine the air/fuel mixture. 

By using the LM1 meter you can determine if the pilot jet(s), main jet(s) or needle(s) need to be changed.

Ignition timing: Many factors can effect the ignition timing requirements of an engine; combustion chamber design, compression ratio, and camshaft timing are just a few.  The type of fuel used is very important, because the octane rating and other factors determine the speed at which the fuel burns.

Most pump gasolines are relatively low in octane rating and therefore burn faster than many racing fuels.

When changing ignition timing for maximum power, you should always start by retarding the timing 2-4 degrees when using pump gas. Most of the newer engine designs have very efficient combustion chamber designs and won't need advanced ignition timing. Racing fuels may be more tolerant or even benefit from advancing ignition timing a few degrees (Proceed with Caution, Pistons are not Cheap).

Final thoughts: Dayton Dyno Dynamometers are designed with low inertia rollers and therefore do not

require an expensive braking system to slow the roller. The engine and rear wheel brake provide adequate

braking force to slow the roller quickly and safely. Steady state testing can be achieved by loading the engine for  tuning driveability problems and Full throttle testing can be achieved by running the engine in the upper gears.

 

  Dyno Tuning   without spending $20,000.00 or more.

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