I never had any problem with the dyna box with spark,when it works it works,NOT The cdi but the 3000 limiter,,I think the spark problem is not knowing what dip switches to flip for the right settings on the right applications.,although as stated I had the same problem my box broke and the relays stuck open on me which causes it to work half the time and run the battery down the other because you have to change the continuity on the switch on the handle...the box is good for the track because the free spin on your crank is not good (reving and holding rpms at the light) but it also fattns your bike up abunch because although the spark is limited you still have the same amount of fuel comming..I would only recomend it for the track.