I had same problem or similar with my 2000 zx50 superfever from cold could get half a mile before loss of power still ran at tick over but wouldn't pull away let it cool and same again. Then by chance discovered if I pulled the brake as I was pulling away it didn't bog down, that led me to putting lights on and it ran. electrical problem r a nightmare so started replacing cheapest parts first, spark plug and coil first then voltage regulator rectifier and then cdi box but as I was installing the cdi I noticed a corroded wire coming from the stator it was down to 3 strands, cut the bad bit out joined the wire . Runs perfect now only problem I think I wasted my money on the parts and I should of peeled the tape bundling cables together to inspect properly the first time. Hope it's helpful