RD 250/350 Ignition Help

[T-Bart]

Hey Gang,

I'm working on my first project bike, a 1974 RD 250 (with a 350 motor) that has sat in a garage since 1990. Right now I'm trying to diagnose why my spark plugs aren't sparking when I kick it over. I have a new battery of the correct type, and new spark plugs that match the old ones (though they aren't necessarily what the Haynes manual recommended for the 350). With the key turned to ACC the headlight, blinkers, and horn work, and with the key turned to ignition a backlight on the speedo comes on. I have tried in neutral and in 1st, with the clutch lever in and out, with the engine kill switch to run and stop and the other engine switch to both on and off. My first question is, what is the proper way to kick an RD? I know it's a stupid question, but the Haynes manual and the other manuals I have don't address this, so I need to know. My real question is what should I investigate first, and how? Tomorrow I plan on doing the ignition coil bench test, so consider that done. I've also looked at the stator and the carbon brushes look fine, not less than 6mm yet and the track is not too dirty or oily. Also the contact breakers don't seem too corroded or fried, they're grayish-black in color. The stator itself has some white corrosion on it and some surface rust, but nothing that immediately raised flags for me. Any advice would be welcome as I am in the dark about electronics (yes, a pun).

Travis

 

[teazer]

Travis, I'd start with a wiring diagram and workshop manual. Horn should only work in the ON position, along with ignition, lights, idiot lights. In PARK the tail lamp should be lit and perhaps a small parking bulb in the headlamp if it has such a thing.

It may have the wrong main switch or something may be wrongly connected. Forget about the alternator and charging circuit for the moment. Focus on getting +12v from battery to switch to kill switch to coils to points. Kill/run switches are a favorite place for corrosion too, so flush that with WD40 and flick it back and forth a bunch of times.

 

[Redbird]

Listen to the Teaser, the Teaser is wise
Ill have to look at my wiring diagram when I get home, but there's a way to check the ignition switch for output I had a bad switch on my DS7 that gave me fits until I figured it out

 

[T-Bart]

After checking with test wires the coils are good, bluish spark from both of them. I will check the switches next. Any advice on how to go about doing that would be appreciated, but I'll hunt up some stuff.

 

[teazer]

Lots of was to check switches. One is to probe it to see which wires have power in which switch positions.

What I tend to do is to grab a multimeter and set it to the Ohms scale, then disconnect the switch and probe every wire in the connector block in every position and then write them down. Look at the wiring diagram to see which colors go where and then trace them. If you think of it as a whole complicated system, it's more than the brain can process, so break it down into small chucks. Owrk through one switch at a time and then check wires one circuit at a time.

Don't be afraid to draw up the circuits one at a time as you test them. That way it all comes into focus. Grab a manual or wiring diagram on line.