I own a 1978 Honda CB400t which I bought on E-bay last October,I have spent quite a bit of time and money restoring my bike over the winter. My bike runs for a few miles then it backfires an stops it is then very hard to re-start.the bike also lacks power.I have suspected the carbs to be at fault ,but on examination they seem ok.I notice on other posts that the coil could be a cause of the problem.has anyone any ideas ??