Motorcycle Repair: Honda V-45 warm start problem, ground paths, bill silver

Question
Hi Bill,
I really enjoy reading your replies to problems people have.
Here is mine I hope you can help, I have a 1982 Honda V-45 Magna, It has about 13,000 miles on it, when it is warmed up from even a short ride, if I shut the bike off it won't start back up until it is cooled off or I pop start it, which will start the engine no problem. The starter turns the engine over but she won't fire. I have not replaced any ignition parts yet the battery is new, as is the starter relay.

Answer
Rich, you may have either some spark module problems, a petcock diaphragm issue. You really need to observe what is missing from the start/run equation. If it doesn't start, access a plug wire, stick a plug in it and see if there is spark. If so, then the cause is more likely fuel. If the fuel tank isn't venting properly, if the fuel filter is partially gunked up, the fuel pump not running or relay not functioning properly, then you won't get enough fuel to the carbs. The petcocks on many bikes of that vintage are vacuum  operated and the diaphragms fail, so fuel flow is restricted  causing starvation after awhile.

There are some V-4 Honda websites out there that cater to Magnas/Sabres and Interceptors, which share a lot of architecture in the engine, fuel and ignition system components. You could have some heat-soaking issues with electrical components, too. Check all electrical connections and ground paths carefully, so all are clean and tight.

Take some tools with you on the next ride, so you can check to see if the carbs have fuel, the engine has spark, etc. That should help you narrow down the source.

Bill Silver