electrical wiz's... AC regulator discussion

[maxamillion]

Ok i just made an ignition wire harness for an XR400 motor. It uses the stock CDI box and igntion coil I just ran the wires. I did not use any type of AC regulator the first time around. It got good spark and ran fine for about 30 minutes ride time. Thats when I stopped getting spark.

I tested the stator it puts out around 40 VAC which should be fine. Then I tested the pulser it picks up 0.7 VAC which is also fine. So I have power to the CDI, but I dont have any voltage running from the CDI to the Ignition coil.

How exactly do the AC regulators operate? and are they needed if no lights or accesories are used? im wondering if something got burned up from to much voltage because it stopped running during straight away in a race.
I thought the regulator was only needed if I had some type of charging system, which i dont.

Any thoughts?

[deathman53]

voltage regulators are hooked up between the hot(access) wire of the stator and the ground. A regulator is not needed if you don't have lights. From the stator there is 2 power circuits(some bikes 3 and mx bikes 1) one is for ignition, its usually 2 poles and the rest of the stator is accessory power. Maybe something was hooked up wrong and you fried the cdi? The trigger tells the cdi when send power to the coil, my guess is somethng is wrong with that. Another question, why whouldn't you just buy a stock harness and not deal with wiring problems?

[wilkin250r]

It shouldn't need a voltage regulator. The coils on the stator are independent of each other, except for the ground. The exciter coils on the stator are used to charge up your CDI (provides the actual "power" for the spark) and they shouldn't be connected to the voltage regulator in any way whatsoever.

[maxamillion]

ok thanks for the input sounds like i shouldnt worry about the regulator. another thing is I used a 400ex CDI instead of the XR400. anyone know what the differance is? I know honda list them as different part numbers.

[deathman53]

the difference is power curve and rpm it makes spark. I remember some years ago, when big gun, white bros and such 400ex boxes were being used, the battery needed to be fully charged and even then it didn't start sometimes. The electric stater will turn the motor slower than our foot and the e-start models had a cdi that lowered the rpm spark. The problem with those boxes is that they were kick start xr250 or xr400 cdi boxes and slightly re-programed w/ a higher or removed rev limiter. Those who had them, when they put back on the stock cdi, it would start on a half dead battery.