I picked up a 1985 250R a few weeks ago and have been battling an issue w/ it ever since I got it. I got it running, but it never would open up, it would just fall flat on its face at WOT. After tweaking w/ the carb w/ no improvements and doing some research, I found that the CDI on it was probably the culprit, due to the fact it was a cheap aftermarket unit and rattled when I shook it. I bought a used OEM CDI off of ebay that claimed it came off of a running machine. I plugged it in and had no spark, plugged the aftermarket one in and had spark...so I returned the OEM unit. Ordered the next OEM CDI, once again guaranteed good working unit, plug it in...no spark. Plug the aftermarket back in..spark??? Do I just have bad luck and received (2) faulty units? Or could there be an issue somewhere that is not letting the OEM CDI work? Is there something that could be frying the CDI's? I plan on going over the entire electrical system, cleaning grounds, and testing for shorts...but I can not figure out why one CDI would work and the other not, other than bad luck of (2) bad ebay buys.