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Programmable Ignition Systems

Programmable or reprogrammable Capacitor Discharge Ignitions are a subject that is very volatile within the world of the 125 shifter drivers and crew chief. The discussions and issues most often reflect the tracks and the series in which the drivers are currently running and not the technical merits or the complexity/simplicity of the devices themselves.

All 125 shifters have a programmable capacitor discharge ignition. These come from the factory with the 125-shifter motors. The factory boxes for the most part are not reprogrammable by the average karter as the software to interact with the factory boxes is closely held by the manufacturers.

The question always being asked is if the stock box is good enough for a dirt bike why is it not good enough for karts. There are a lot of similarities and a lot of differences when comparing dirt bikes and karts. lets look at some of each:

Similarities Differences
Immediate response to throttle. Kart driver combination is typically heavier.
Little clutch use. Dramatic differences in gear ratios.
Limited ride time, short sprint races Up to 30 minutes at near full throttle for Karts
Limited grip, lots of slip. High grip and limited slip

When you utilize a dirt bike the usual scenario is that the bike is run off road, the throttle application is a constant on/off application of power due to the nature of the limited grip and the very low gear ratio utilized in dirt bikes. Tires experience limited grip and lots of slip due to the inability of the off road surface to hold the applied power. Dirt bikes also have their rear wheel in the air a good portion of the time.

The motor manufacturers take all of these characteristics into play when they deliver a programmable capacitor discharge ignition system for the dirt bikes. There is little worry about timing advance or retard as the on/off throttle operation of the rider is not really taxing the motor and the constant accelerate and decelerate does not put a lot of timing related heat into the motor. Even if it does the constant loading of the cylinder with fuel more than offsets any heat build up. The manufacturers also plan that the bikes will spend some of their time in the air with the throttle at wide open and the manufacturers plan the ignition timing so that the motors are seldom harmed from this action. These manufacturers know that the moto cross bikes have to perform well and they also have to be reliable. Bikes have approximately two dimensions to their spark control map and do not alter the ignition advance with respect to load. Generally the cylinder charge is relatively low during part throttle operation and the bikes give better response with more spark advance than the bike will tolerate at full throttle for sustained periods.

Those characteristics are exciting when on a dirt bike but they are not really the characteristics for a good 125 shifter kart. Letís begin with the kart itself. 125 Shifter Karts are heavy and karts with their inherent design have high rolling resistance during cornering, Karts seldom have their rear wheels in the air, karts are on sticky tires compared to bikes and kart tracks have much greater traction than most dirt bike venues. This means that we are asking the same motor and the same programmable capacitor discharge ignition system that is used on the bike to work for karts. Port work and pipes do help with some of the differences but we still face the fact that karters are leaving significant performance on the table with the factory programmable capacitor discharge ignition system. All of the race bikes have tuners have the capability of modifying the factory supplied ignition systems at each event. They seldom rely on the factory supplied programmable capacitor discharge ignition system for consumer use. Factory demographics indicate that approximately 85% of the 125 motorcycles produced are never applied in a race situation. The stock programmable capacitor discharge ignition systems have typically only 15 timing points on a curve while the reprogrammable capacitor discharge ignition systems have up to 50 timing points on a curve. The factories recognize that the products shipped for typical consumption need passive rev limiters and need to be able to function for the person, running only pump gas and perhaps chain saw oil. The consumer will even run the motorcycle with a fuel oil mix of anywhere from 20 to 1 too a mix of 50 to 1. The programmable capacitor discharge ignition system for the stock motor is made to accommodate these variables to protect the average motorcycle consumer. Those characteristics are a far cry from what the average shifter kart driver is asking from his motor.

So what do reprogrammable capacitor discharge ignition systems do that stock ignitions do not do. The answer is they let the karter or the motor builder apply a custom ignition curve to take advantage of changes such as revised porting, different cylinder heads, pipe or jetting changes and even fuel octane level variances. The result is that there is improved power delivery, there is also the ability to control power jets with multiple on/off settings, an adjustable rev limiter to force the driver to shift so that the engine stays within the power band or to prevent over revving the motor. We have seen dramatic improvements in engine reliability as the issues which caused detonation and or heat build up have been eliminated.

The concept sounds great but it also sounds complex, technical , hard and expensive. We did our research and we worked with one of the premiere motor builders for 125 shifter karts. Let me assure you that the complete process was not beyond the capability of anyone that is tuning and effectively competing with a 125-shifter kart.

The tool we used was a Vortex Performance Ignition tool and a laptop computer. The process took minutes to complete with initial telephone assistance from Vortex Performance Ignitions. I did however have an expert user looking over my shoulder. The expert we selected was Bill Price of Bill Price Racing, Gilmanton Iron Works, New Hampshire (603) 364-2455. Bill Price develops WKA and SKUSA shifter motors. We asked Bill to show us examples of the same motor with a stock ignition box and then with a programmable box where he had designed an ignition curve for a reprogrammable capacitor discharge ignition system. The results were impressive. With the stock box the motor made power up to about 12,300 rpm's and began to fade, with the reprogrammable capacitor discharge ignition system the same motor continued to make power through 13,000+ RPM's. The torque and horsepower curves were moved relative to RPMs and we saw the EGT and CHT actually decline. The bottom line is the same motor under identical conditions delivered added horsepower with the reprogrammable capacitor discharge ignition system.

Once Bill was complete with his demonstration we tested the ignition curve which I designed and I was surprised to see that my solution was fast but would not be viable as I was putting far to much heat into the motor through advanced timing and would detonate the motor if we let the dyno run continue.

Bill Price then took me back to the Vortex Performance Ignition development tools and showed me how to use the Ignition Curve Editor (ICE) Software and how to overlay the curve which I had developed with two other curves which were already stored within the Vortex Performance Ignition Curve Editor and I could immediately see that I had substantially deviated from any of the sample curves provided. I simply left too much advance in the ignition curve as the RPM's increased.

Using the (ICE) software I was now able to visually see what impact my changes were having on the motor. The (ICE) Software allowed me to not only see the curve for the Yamaha YZ125 that I was programming but to look at Honda, Kawasaki, TM and Suzuki motors and see how each manufacturer applied their ignition curves. It immediately became easy to see the reason that the different brands seem to have different performance at different points within their respective power bands. I could see that I would need this software even if I was going to run only stock boxes so that I could review the curve of each stock box and know which year stock box that I would apply for which track condition.

Within 125 shifter kart competition there are race series which require only the use of stock programmable capacitor discharge ignition system boxes. For the stock boxes there are no available reprogrammable tools so the process is one of replacing one year stock box with a different year stock box. With stock boxes a technical rule the teams are forced to inventory multiple stock ignition boxes and sometimes even multiple ignition rotors and stators to allow the team to tune for a particular track or for a particular condition. As you would expect inventorying of a host of ignition boxes, stators and rotors can be a significant expense.

The reason for utilizing the (ICE) software editor to understand the available factory ignition boxes is that there are no readers which allow us to read the stock box so many of us have been buying different boxes and doing dyno and on track testing. The Vortex Ignition Curve Editor software contains all of the information relating to the stock boxes so that I can overlay up to seven different years of stock box and determine which is best for my application needs of the day. I can also look at what is available for my competitor to apply as I can compare what curve I'll run versus what is available to my competitor. The stock boxes are not inexpensive, prices range from $160 to as high as $400 for a stock box.

When doing our research to select a reprogrammable capacitor discharge ignition system one of our most significant concerns was the computer intelligence needed to operate the tool. We asked for references and we asked to details concerning support after the initial purchase. We selected the Vortex Performance Ignition as this was the product where we were told that the less computer sophistication the better. In fact it is best to not try to out think the tool but to just follow the simple directions and to use the telephone support line to achieve success.

The reprogrammable capacitor discharge ignition system that we work with on our team is the Vortex Performance Ignition system. It was selected by our engine builder and we have spent our energy developing a program that supports the needs of our drivers. We separate the drivers into two groups. One set of drivers have reprogrammable capacitor discharge ignition systems and a two position switch so that they can select either program "A" or program "B". The other drivers have an eight (8) position switch and their reprogrammable capacitor discharge ignition systems have eight (8) different programs. The switches are located within easy reach of the driverís hand so the driver can change programs while practicing for a race event. At the end of each practice round we download the data from the various on board systems and have discussions with the drivers about what they like and what they need. Having drivers with different types of motors and different driving styles then allows us to make the changes necessary to be competitive. The drivers with the eight curves give us the most data but for very short duration. The drivers with two programs give us data over a longer duration. The trick then is to find the compromise which will make the Yamaha 125 and the Honda 125 both perform and to accommodate the driver who is 50 pounds over weight and the driver who just makes weight. As you can imagine the ignition curves are never the same. For the drivers with a lot of experience we can do timing adjustments as fine as 0.2 degrees and we can apply 50 individually adjustable curve points across the rpm range. We can get the performance exactly where the driver wants the perfromance. For our novice shifter drivers and even our veteran shifter drivers we also have a selectable rev limiter. Some drivers like to sit at the start with the motor on the rev limiter waiting for the flag others just want the security of the rev limiter in case of an off track excursion.

Vortex Performance Ignitions offers several levels of product for the racers. There is the Race Team Kit which has the reprogrammable capacitor discharge ignition system, the cables necessary to connect to the PC, the PC software but for only one brand of motor. It covers multiple years but still a single brand such as only Yamaha or only Honda.

A second option is available which is the Engine Tuners Kit. This kit has the reprogrammable capacitor discharge ignition system the interface cables for the PC and the PC software but for a host of brands which include Yamaha. Honda, TM, Suzuki, Kawasaki, KTM and Husky.

The pricing is: Race Team kits are offered for $799 and Engine Tuners Kits are offered at $1099. The US source for the Vortex Performance Ignitions is Mike Tole of MT Racing, 7505 Juniper Avenue. Suite C. Riverside, CA 92504 http://www.mtracing.com

Contact MT Racing 7505 Juniper Avenue. Suite C. Riverside, CA 92504 http://www.mtracing.com
for Vortex Performance Ignitions. email mt@mtracing.com
Contact Bill Price Racing, Shannon Road, Gilmanton Iron Works, New Hampshire ZipXXXXXX email bpracing@worldpath.net 603-364-2455

Bob Chiras
Crew Chief
AllKart International
603-432-4766 home
781-442-3045 office