Hi, Can someone with some mechanical savvy offer any sort of diagnosis on this issue. This 2004 model Honda VTR 250 has a misfire going on up to around 4000 rpm. Brand new plugs were put in and after only twenty kilometres the plugs were pulled and look like the ones in the attached photo. The dirtier one with all the deposit is from the front cylinder. What could be going on, sorry not very experienced mechanically and this is not my bike. The owner thinks that both are getting spark. Thanks,