'06 YFZ coil question...

[ElderGeek]

The Fofiddy died on me at Chinawall this weekend. Was running up & across the face a bunch of times but on a training run for a noobie duner, right at the bottom, out of the blue, it started popping and snapping when under power. I needed to keep feathering the throttle to keep it going as I turned and came back down the face. Once down on the flat it would not idle then finally died even though I was working the throttle. Then it would not fire. I couldn't really tell if it was rich or lean. I suspected something plugging up a jet or other orfice in the carb given we are at the dunes and it has been blowing hard everyday. Sumpin might have got in there.

Here is a clip if it. The sounds you hear as I am coming down the hill is the backfire and snapping I mentioned. Listen a few times and tell me what you think. The clip starts just as the problem starts.

Chinawall


The air breather was fine, so we pulled the sparkplug to rule out a spark issue but found we had no spark at all. We double checked all the switches, I removed the kill tether from the circuit, but still no spark. And the plug was a nice color, dry with some light 'spatter' on the ground pin, (like very, very small wire weld spatter). The Positive blade terminal on the coil shows signs of arching. (the end that receives the CDI signal) Could this spatter be caused by the coil going bad while running?

I am troubleshooting my ignition circuit. YFZ's have a coil on top of the sparkplug, is it possible to take a reading on the 'connector' that plugs into the top of the coil? This is the signal from the CDI box.

I would assume this is a 12vdc signal with the coil bumping it up to fire the spark plug. Is this correct? I would also expect to see the voltage jump up and down at this connection when I hit the starter.

I ohmed out the coil and it is close to spec, but not right on. The carb & throttle switches ohm good. I just want to be sure its not the CDI box when I pick up a new coil.

[freakn450]

Nasty.... My DS did the exact same thing, and it turned out to be the rectifier. I spent months trying to figure out what was going on. Everything tested good, etc. If you can get your bike started, and it's running like crap again, turn on your lights. If clears up, then it's your rectifier.
Also, did you check your battery? If the cables are loose, it'll run this way too.

[ElderGeek]

The problem is I am not getting any spark. The motor cranks just as it always does. Battery cables are clean and tight. Tail light comes on and brake lights work.

I keep getting different readings on the ignition coil every time I check it. Looks like I will need to order one to try. Can't find one in town.

So no one knows the output voltage from the CDI to the ignition coil?

Does anyone have a working CDI I could test with?

[freakn450]

Man, too bad your not here in Tucson. I'd let you borrow mine...

[ElderGeek]

With new coil in hand, (finally arrived today) I plugged it in to see if I have spark.


Nope! not even a little whimper of a spark. I tested all the switches again, they all test good, I check the pickup coil, within specifications, just like before. So it looks like its the CDI box is dead.

So is there anyone on the east side, (I'm in Gilbert) that has a YFZ I could borrow the CDI box from to be sure that is my problem? I would really like to know for sure before I order a new one. Once bought you can't return it.

And if I end up needing to buy a new CDI box, is there an aftermarket model that would be worth running on my "no engine work" Fofiddy? Or should I just stay with the OEM or GYTR versions?

2006 YFZ
stock pipe w/ pea shooter removed, (hope to get a Dasa or Sparks though)
Trinity filter kit
Jetted (with the help of Kramer!)
Cam mod
15/38 sprockets
Desert trails, Dunes, TT racing

[CADWELL]

With new coil in hand, (finally arrived today)

And if I end up needing to buy a new CDI box, is there an aftermarket model that would be worth running on my "no engine work" Fofiddy? Or should I just stay with the OEM or GYTR versions?

ElderGeek, I've read and have been told that the way to go is and adjustable CDI for the YFZ like the Dynatek FS or a Vortex, for modded up machines.

I believe the Dyna has 4 different power curves that are adjustable on the fly and the vortex has 10 different setting to ride on.

Other then that I hear that Dee from RAGE ATV who's a well respected engine builder likes to run GYTR cdi with his YFZ builds.

[ElderGeek]

"..... for modded up machines."

Having only done the basics, airbox cover, filter, jetting & Cam Mod, I wouldn't think mine would qualify as a "modded quad. (No motor work). I could see the benefit of the spark curve but the rev limit increase on a stock motor, not so much.

Am I thinking correctly?

[ElderGeek]

Well, I borrowed a CDI and still no spark. Put my CDI in another YFZ and it fired right up. So it's not the CDI. All that's left that I am aware of is the Magnito. I'll pull it apart this week, but if the woodruff key is ok I am at a loss as to what it is.......


I want to thank forum member sticksyfz for letting me borrow his CDI box for testing. He doesn't post much but stepped up to help out a fellow rider he never met & does not know. (Well, we know each other now..) We talked for a couple of hours about our past racing experiences and had a few beers. Thanks again sticksyfz for use of the CDI and thanks for the beers. And I too have a leaking water pump seal. Oh Joy!

[sticksyfz]

Your welcome for the cdi and glad i could be of assistance.Hopefully you get it fixed soon and see you out at the dunes and if you got any questions on the water pump seal just let me know!

[desertdeweller]

check your stator stators usually will fail before anything else typically coils and cdi are very durable. there should be a lighting coil side and a ignition coil side on your stator the ignition coil side is the one you will need to test. stock ones are usually pretty durable as well. I have purchased a ricky stator and it was junk in just over a year. I know a lot of other people that have had problems with ricky stators stuff the last few years. you should be able to ohm test it to find out.ohh You might be having a problem with your tether too . I don`t know how you have yours wired but have heard of a few people shorting some stuff out with them. I think they wired there directly to the coil though. If yours is wired to the stator you might disconnect it first maybe the tether switch went bad and your key switch if you have it. if all that checks you might have to start chasing wires