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I have a '86 Yamaha yx600s Radian that has weak spark from one coil and even weaker spark from the other. I've wasted a bunch of money replacing the coils, the pick-up coil, and the ignitor box, but the problem persists. Does anyone have a new suggestion? I've tried to check the wires but without a wiring diagram telling me which wires should go where I'm not sure what voltages, if any, should be, or what resistances should be and between where. I will get a book soon and that should have something, but I was hoping someone here might have better ideas, being more experienced than myself.

Thanks in advance

Have you changed the HT leads to the plugs?

Yes, I got new ones with the coils. I believe the problem to be before the coils because the coils are pretty much identical so I switched sides and the same side was weaker with either coil.

find where the ground wire from the battery bolts to the engine and remove and clean it with sandpaper.clean it here it bolts to also.if you have an ohm meter check it to see if it is corroded inside.do the same for the positive cable.

The resistance between the negative battery post and various points on the engine/trans. and frame, and there was about a half an ohm to all the points I checked. I also checked as many of the connectors as I could find.

I am now wondering if the flasher unit might be causing the problem. The blinkers don't always work and when they don't I can wiggle the wires going into it to make it work. I think it has a loose connection inside that is affected. But if I disconnect it completely the starter won't work at all. What do some of you more experienced people think of this?

does it have a part number on it--i have some radian stuff i can send you if i have it.

It's a black plastic box about 2 inches by 2 inches by 1 inch and the connector has 9 pins. The big number across the top is 41R-71. On the next line, smaller, it has FX257N. On the next line, even smaller, the number has partially worn away but it starts 0665, has 4 or 5 numbers missing, and ends with 571. Then it tells what it is and it looks like it was made by Nippondenso. Then the last line says DOT, has an A with a circle around it, and has the number 799977.

i have got one.

Cool! I'll PM you.

kkleparek wrote:Cool! I'll PM you.

did you get my reply to PM??