Rear coil problems

Hi All

I posted this in the wrong section,hoping I get some help/advice.

My 2005 Yamaha Royal Star Tour Deluxe.I noticed that the right rear ignition coil was not working. Bought a new coil and put that on and still not firing.(no spark to plug).

So done the usual tests and everything is fine. On the left rear coil the wires are red/black and orange.

The right rear coil is red/black and yellow. Where I was tired I put the orange wire from the left rear coil on to the right rear coil in error. But then I got a strong spark?.

I have checked and tested everything I can and now I am losing what little hair I have. As I said if I put the orange wire from the left rear coil on the right rear, it sparks, but obviously that cant be right.

The bike starts, OK it runs a bit ruff/low on power but it runs, all lights work, etc etc.

Bike has had new plugs, new HT caps.

Only thing left is the plug......doesn't make sense to me.

Now if you put the yellow one on the left, does it spark? If not I would suspect a broken yellow wire.

If I put the yellow wire on the left coil it does not spark.

But here is the confusing bit. When I put the orange wire back on to the left coil it's not sparking as well now.

I am just trying to work out where the orange and yellow wires go to. I presume one to the ignition and one to the ECU box.

I am doing some more checks today. Just so frustrating.

As I have said the battery is good, both coils are new,checked HT caps,fuses are good.

Today I am going to check all the wiring,to see if anything is broke or a dodgy connection.

Any updates?

been thinking about this one. I suspect you have one of following (AS LONG AS TIMING IS GOOD,no changes on crank, cam, timing chains, etc...in which case bust out a timing light out).

Question:did you check spark plug gap (.031or .8 to .9 mm)?

1. bad coil-your first coil never worked if I read this right we’ll call it num4, but coil num3 worked in num4 spot, but not working as well when back in 3. Recommend checking the connection and a little dab of dielectric grease. Hope I got that right I’ve been recovering from kidney stone surgery.

2. A bad ground- you may have a faulty ground somewhere (possibly even the coil itself and/or the wire is jumping spark or arching to the frame or engine, this happened to me once on a car) these can drive you insane and do weird things on any engine.

3. A bad ecu timing controller- seems unlikely to me, but rule it out.

I Invested in an in-line spark tester(can get at any car store) https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6 I also bought one of these spark testers. http://www.sears.com/lisle-corporation-spark-tester/p-SPM7341565609?plpSellerId=salefolks&prdNo=42&blockNo=42&blockType=G42

I would hook this up and validate spark on all 4 coils. Do yourself a favor and turn power off before moving the tester. Ask me how I know. If I was missing spark I would look at the wires for broken wires, bad coil, (seems unlikely to be a plug but hey that’s what this tester will show) or bad ground. Final test on the dead wire going into coil (theoretically unnecessary) hook up multimeter at connection and validate spark coming from spark controller (ecu or whatever its called). If I had spark on tester but not plug, change the plugs. Most of the time working on gas, small engine, outboards its been a coil/plug wire.

Let me know what you’ve found. Oh and watch out for bad neutral safety switches (but that would cut all power so unlikely here)

Thanks . I have given up,the bike is off to a local mechanic today. My local Yamaha dealer would not touch it as it's a " Non European Model".

I shall keep you updated with the outcome.

I think it's a bad connection/broken wire somewhere.