QuestionI just bought an 83 Shadow and have been having trouble getting her started. I put a new battery in just the other day. She starts cold fine. But after she warms up she doesn't want to turn over. She will start when jumped just fine. Otherwise she just cranks and cranks and cranks. I am not sure where to look next.
Thanks
AnswerJustin, sounds like some kind of "hot soak" issue, where components are going out of range when the engine heats them up.
http://houseofmotorcycles.bikebandit.com/honda-motorcycle-vt500c-shadow-1983/o/m...
for illustrations of the various parts.
Some things to check out are:
Petcock cover... diaphragms can fail or weaken causing a shutting down of the fuel supply.
Pulse generators... often fail, but you need to check the bike for spark when it doesn't start. If there is no spark when hot, you have to consider the components involved in the ignition system... pulse generator (failures not uncommon), the spark unit(s), the coils and the spark plug caps.
You should check the resistance of each spark plug wire with an ohmmeter (cheap VOMs available at Radio Shack or Walmart, etc). Resistance in the wires/caps are generally around 5k ohms. Coil primary and secondary wiring should be checked and compared to the other unit.
From the drawings, which don't give real details, apparently Honda had either two separate spark units and at some point in time, just a single assembly servicing both coils/cylinders. These are hard to check so would be the last item to consider replacing.
The ignition system is not battery operated, it is self-powered, so whenever you can get the engine to turn over, it should start up on its own. Note that wiring for the ignition goes up through the handlebars into the KILL switch (on-off) switch on the right side. Kill switches on a CDI ignition actually put a ground on the wiring to the coils, instead of opening a circuit, which a battery ignition system would require. Any kind of loose connections, intermittent grounds and bad switch contacts can cause problems with the ignition system.
The pulser coil wire connectors come up from the engine and can be checked with an ohm meter statically or you can test them by looking for a voltage being generated from the pulser coils.
Suggest you get a repair manual if your owner's manual doesn't have a wiring diagram in the back of it.
Remember to start an engine, it needs compression, spark (at the right time), and metered fuel/air into the carburetors.
Keep some tools with you, when you take the bike out and/or take it for a ride and plan to come back home and then test for spark and signs of fuel on the spark plug. If there is spark, but the plugs are dry, then you have a vacuum leak or air leak in the intake system. If the plug is wet and no spark, then you have to look at the ignition system components. Not so easy to work on these days, in comparison to the "good old days" of points and condensers.
Good luck,
Bill Silver
