are CDI's all the same?

[wpginterceptor]

as long as the connector is the same will different model CDI units interact?

[Flyingw]

No!!!!! Not the same. Different engines have different ignition timing curves.

[YTZ drew]

Not sure if it makes a difference, but trigger coil location may be a factor as well, some engines trigger off the cam, others get their source and their trigger from the crank. Anyway, the correct CDI is usually pretty easy to find for most bikes. I have a friend who has about 3 of every ancient cdi box known to man.

[Flyingw]

Yes the trigger (pickup coil) position absolutely matters. The trigger coil tells the CDI when to discharge and fire the plug whether its on the CAM or the crank. The trigger coils are hard mounted in that there is usually no means of adjusting the position so the timing is fixed. That timing position is part of the programming that goes in to the CDI. Now the 185/200 series motors do have pickup coils that have mounting plates that do move according to the RPMs but there are no user adjustments. All of this matters relating to the CDI an the factory timing curves that are unique to each CDI.

[big specht]

It kind of depends one what bike it's for too there are differant ones that looks the same and plug in the same but like what was said before there are differant ignition curves from differant manufacturers

[sledcrazyinCT]

Not sure if it makes a difference, but trigger coil location may be a factor as well, some engines trigger off the cam, others get their source and their trigger from the crank. Anyway, the correct CDI is usually pretty easy to find for most bikes. I have a friend who has about 3 of every ancient cdi box known to man.

Got a friend wanting to purchase a CDI for a 1979 XR500. Does your friend sell any off?