lokie168 Posted September 3, 2012 Report Posted September 3, 2012 Is it okay to change the contact point type dizzy for a cdi one? what benefits will I get for this? Quote
GJM85 Posted September 3, 2012 Report Posted September 3, 2012 I'm using a streetfire cdi with a GT40 coil and desno dizzy. Still using the points. Works well. What you want is a Hot Spark. http://www.hot-spark.com/ Quote
lokie168 Posted September 3, 2012 Author Report Posted September 3, 2012 so you can use both cdi and contact point dizzy at the same time? Is it good for my 4k engine if I only use cdi? Quote
snot35 Posted September 3, 2012 Report Posted September 3, 2012 It's really depends on what you're talking about, there are many different CDI units. Some are actually triggered by the points as an after market kit. They usually put less current through the points making them last longer. Some kits actually replace the points with magnetic or optical triggers, but effectively they are more or less the same. As long as the CDI box is triggered properly and you have a coil that is compatible with the box you should be fine on a 4K. What CDI are you looking at? Quote
lokie168 Posted September 3, 2012 Author Report Posted September 3, 2012 wanting to change the dizzy and changing points and condenser for a CDI. Quote
altezzaclub Posted September 3, 2012 Report Posted September 3, 2012 Just get the 5K electronic dizzy and change the springs in the base. I'm running the stock 4K coil etc and its has been problem-free, it just needed the advance to come in earlier in the rev range. Certanly runs a larger plug gap and eliminated any low-down hesitation. Somewhere in here- http://www.rollaclub.com/board/topic/42407-the-girls-ke70/ Quote
snot35 Posted September 4, 2012 Report Posted September 4, 2012 Do that. CDI is a generic term which could mean anything. The above mod is bolt in without having to do a heap of work. Quote
GJM85 Posted September 4, 2012 Report Posted September 4, 2012 (edited) CDI is a capacitor discharge ignition. The unit allows the coil to charge faster than an inductive ignition. The coil can deliver between 9 and 18 volts off a 7 volt charge for example. The sacrfice comes as a shorter spark so timing needs to be spot on. The streetfite delivers continuous spark for 20 degrees of crank rotation up to 3000rpm and the faster coil charging helps with high speed driving. Edited September 4, 2012 by GJM85 Quote
altezzaclub Posted September 4, 2012 Report Posted September 4, 2012 Jeez Gavin go back and edit that! How does the 9 and 18volts off a 7volt charge work? Does the CDI unit take 12volts, boost it to 18 and then feed that into the coil? (which is how I thought they worked) Then the secondary side of the coil puts it up to 30,000 or 40,000volts. Quote
GJM85 Posted September 4, 2012 Report Posted September 4, 2012 Jeez Gavin go back and edit that! How does the 9 and 18volts off a 7volt charge work? Does the CDI unit take 12volts, boost it to 18 and then feed that into the coil? (which is how I thought they worked) Then the secondary side of the coil puts it up to 30,000 or 40,000volts. Sorry. I was on the phone before. A shitfone. Ere... http://en.wikipedia.org/wiki/Capacitor_discharge_ignition Most ignition systems used in cars are inductive discharge ignition (IDI) systems, which are solely relying on the electric inductance at the coil to produce high-voltage electricity to the spark plugs as the magnetic field collapses when the current to the primary coil winding is disconnected (disruptive discharge). In a CDI system, a charging circuit charges a high voltage capacitor, and at the instant of ignition the system stops charging the capacitor, allowing the capacitor to discharge its output to the ignition coil before reaching the spark plug. A typical CDI module consists of a small transformer, a charging circuit, a triggering circuit and a main capacitor. First, the system voltage is raised up to 400-600 volts by a transformer inside the CDI module. Then, the electric current flows to the charging circuit and charges the capacitor. The rectifier inside the charging circuit prevents capacitor discharge before the moment of ignition. When the triggering circuit receives triggering signals, the triggering circuit stops the operation of the charging circuit, allowing the capacitor to discharge its output rapidly to the low inductance ignition coil, which increases the 400-600 V capacitor discharge to up to 40 kV at the secondary winding at the spark plug. When there's no triggering signal, the charging circuit is re-connected to charge the capacitor. The amount of energy the CDI system can store for the generation of a spark is dependent on the voltage and capacitance of the capacitors used, but usually it's around 50 mJ, or more. The standard points/coil/distributor ignition, more properly called the inductive discharge ignition system or Kettering ignition system, produces 25mJ at low speed and drops off quickly as speed increases. Quote
altezzaclub Posted September 4, 2012 Report Posted September 4, 2012 fair enough- a bit more than 18volts then... even the low voltage side of the coil will make you jump! Loki the options are being discussed in Dust's Hotspark topic, which I assume you're keeping up with. Quote
GJM85 Posted September 4, 2012 Report Posted September 4, 2012 (edited) fair enough- a bit more than 18volts then... even the low voltage side of the coil will make you jump! If you crank the engine with the lead off the coil it throws a spark the size of a match stick to the negative coil terminal. I've copped a shock a couple of times now and it makes your heart race. Edited September 4, 2012 by GJM85 Quote
GJM85 Posted September 4, 2012 Report Posted September 4, 2012 (edited) Doing this once only for filming purposes. Down right dangerous and I could have blown my car up. Edited September 4, 2012 by GJM85 Quote
styler Posted September 5, 2012 Report Posted September 5, 2012 (edited) delete Edited September 5, 2012 by styler Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.