No Spark!!!!!!

nasonjs · Dec 10, 2007

I just finished rebuilding the engine on my 660 raptor. I took off down the road and got to the bottom and it stopped.
When I took it back to my garage I found I had no spark. I swapped out the cap and the plug.

I checked the coil as per the workshop manual and that seems ok.

The bike turns over fine but I have no spark. I made sure the run switch was in the run position.

I disconnected the rectifyer and then I had a really good spark.
I checked the stator plate connections and the primary coil was within spec but the secondary coils should have been 0.06 ohms according to the manual and I got a reading of 0.2 Ohms. I am not very confident with the last reading as I don't think my meter will read such small resistances.

Reading previous topics I am expecting that the problem is the stator but I would have thought I would have had very high resistance from one of these coils (Open circuit).

I also dont understand why when I disconnect the rectifyer I get a spark. I would have thought that when I disconnected part of the electrical system nothing would have worked.

Can anyone explain why this works the way it is doing and let me know how to verify it is the stator?

Thanks

willykiller · Dec 11, 2007

First of the rectifier has nothing to do with spark, the rectifier changes the charging circuits ac to a dc voltage to charge the battery and operate lights, the other part of the electrical system from the engine is the trigger coils out put to the CDI unit, this is a low voltage signal amplified by the CDI unit. The trigger coil sits over the flywheel.
The two systems have nothing to do with each other other then the fact they reside in the same engine.
It is a known problem with raptors that the two systems can short together and cause the ignition system to malfunction thereby when you disconnect the rectifier the engine will run,

Pleasuresburban · Dec 11, 2007

I had the same problem several times. Ive been threw 2 cdi's..well come to find out what the main problem shorting them out or whatever happened..was the wiring harness directly under the CDI box gets smashed by the plugs at a 90 deg angle and begin to wear and smash and rub wires.Could even have a break in it. So I bought a BRAND new Yamaha wiring harness from the dealer and havent had any problems yet.( Well Becuase its only ran once and torn apart ) :lol:

nasonjs · Dec 11, 2007

Thanks for the assistance and explanation

I will see if there is any continuity between the two coils on the stator.

I will also remove the CDI unit and have a look at the wires underneath

Thanks for your help!

QuadManiac · Dec 11, 2007

As Willy said, it's a short between the HV and charging coils in the stator, very common. When you disconnect the stator, the HV coil is no longer pulled down and is allowed to generate the voltage that the CDI needs to make the spark. Stator needs replacement.

No Spark!!!!!!

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