SideXSide Action - April 2008 - (Page 48)

TECH CDI & ECU O CDI & ECU BOX WHAT MAKES THEM SPARK? >> STORY BY CHARLENE BOWER The CDI coordinates everything and tells the ignition coil when to fire the spark plug. The history of CDI systems can be traced back to the 1950’s together with the development of other electronic ignition systems. The first commercial motorcycle using the CDI system was manufactured by Kawasaki. (Before the CDI, points controlled ignition systems.) allowing for a longer, more intense spark. They may also add other features like rev limiters, reverse limiters, timing curves, and more. TECHNICAL ur brains tell us how to function every day and there is no difference in your Side X Side…it really does have a mind of its own! The brain of a Side X Side is the CDI (Capacitor Discharge Ignition) box for a carbureted engine and an ECU (electronic control unit) for a fuel-injected engine. Don’t get confused; you can only have one brain, not two! These brains, or little black boxes as they are sometimes called, control different aspects of the engine and how it works. A CDI and an ECU have some different features and you are only going to be interested in one, so I’m not going to confuse the situation by trying to compare them. I am just going to describe them individually. CDI: The combustion of an air/fuel mixture is initiated by an electrical spark. A typical CDI module consists of a small transformer, a charging circuit, a triggering circuit, and a main capacitor. How does it work? Let me try to explain…. First, the system voltage is raised by a transformer inside the CDI module. Then, the electric current flows to the charging circuit and charges the capacitor. When the triggering circuit receives triggering signals it allows the capacitor to discharge its output rapidly to the ignition coil, which hits the spark plug. (Did you get all that? You’re lucky; you only had to read it. I had to figure out how to explain it in writing!) So to put it in one easy sentence: a CDI uses discharge current to fire the spark plugs. The first commercial motorcycle using the CDI system was manufactured by Kawasaki. (Before the CDI, points controlled ignition systems.) FACT: ECU: Let’s start with a CDI box since it came first with carburetion. An aftermarket CDI ignition system greatly increases the voltage available to the spark plug, With the introduction of the 4stroke, fuel injection has become more popular. The ECU tells the injectors to add more fuel or take it away. It basically calculates how much fuel needs to be released. This is why a fuel-injected engine starts so quickly. As soon as the key is turned on to the start 48 SIDE X SIDE ACTION MAGAZINE

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SideXSide Action - April 2008 Contents Mailbox News Tips & Tricks Race Interview Next: Bobcat Soldier Meadows Win a Rhino CORR Season Wrap Up Race Year in Review Built For It: Rath Racing Prowler Product Review Shock Adjustments Tech: CDI & ECU Boxes Company Spotlight: Legend Off-Road Wheel Buyers Guide SXS Shoot-Out Gallery Shot New Products On The Go Photo

SideXSide Action - April 2008

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