Hey guys! i just purchased a custom yamaha xs 650 chopper. unfortunately my xs 400 got run over so i joined the 650 crew! anyways i took it out on the highway and as soon as i was up to 100km/hr for maybe 10 minutes, the bike would lose power in one cylinder. some time both and sometimes it would change cylinders. it seems like its running really hot and i thought maybe it could be the points not being upgraded. the bike runs fine in the city. alittle bit of backfire due to the straight pipes but i need to sync the carbs yet still. it seems to not be buring the fuel proper . but Any ideas why only at this speed it would shut a cyclinder down. sparks are brand new and have good burns on them. carbs have been clean inside and out.