Just bought a WR426, took it out for a ride to run it in, noticed it was missing at about quarter throttle. Thought it was the jetting but I can't jet it out of it. Swapped the TPS and CDI over with another one but it still did the same. We are pretty sure it's in the electrical/computer system somewhere but stuffed if I know what it is. Has anyone else encountered this problem? Have got a 99 WR400 and have had no problems with that.