QuestionI just bought a 1980 Yamaha 400 and i had it running and then my friend wrecked it in to a barn and broke the rear turn signal. Just so you know. Anyways i can get it started with a battery charger on it but when i took it off it dies.What can i do to test the problem...and where should i start...and i don't know if it relates but if i get it started and pull the choke all the way out it dies...
AnswerChris, the bike probably has a battery-powered ignition system, so if you have a dead battery or the bike isn't charging, then it won't run.
You didn't say if it was a DT400 or a street bike, but probably both have similar ignition systems. Start with a fully charged battery and then see how it runs. If the bike sit for more than a few weeks the gasoline separates, evaporates and plugs up the idle circuit jets. So, they are hard to start and won't run well or idle at low speeds.
Clean out the fuel system, including petcock and carburetor thoroughly.
Probably get fresh spark plugs while you are at it.
Put in a fresh or fully charge the battery and go from there. If the bike runs fine for 20 minutes then starts dying then the charging system needs attention. See below link for troubleshooting chart.
http://www.electrosport.com/technical-resources/library/diagnosis/pdf/fault-find...
Bill Silver
