2002 WR426 not running, suspect CDI


13 replies to this topic
  • Alternative

Posted April 26, 2008 - 01:42 AM

#1

OK, here's the scenario:
My WR426 was running fine until about 2 weeks ago, when it started running a bit rough. I went for a 2 hour ride with my dad and on the way back through the twisties it started backfiring and missing. After a few minutes however, it went away and ran fine for the rest of the day. I put this down to the fueling getting a bit messed up during a lot of on-the-throttle, off-the-throttle action, and didn't think anything of it.
For the next 3 or 4 days it ran fine, however starting was a bit more difficult and it started stalling shortly after kicking it to life, something it's never done before. It's coming into winter here in NZ and over those few days the temperature dropped quite significantly, so thought this was the cause of the hard starting.
The next day it started first kick and sounded perfectly normal. I rode down to my friend's house (about 5 minutes away) and as I was turning into his driveway, it died, as though I'd hit the kill switch. I thought this a little odd so tried starting it back up. For the first 20 or so kicks all I got was the occasional really loud backfire. By this time my foot was sore so I gave up for a while. I went back 15 minutes later and this time I got it going, but it was running like a bag of bolts, it wouldn't idle or rev up, I had to hold the throttle just off idle to keep it running at all. It then just died and I unsuccessfully tried to get it going again.
I wanted to pull the plug so had to borrow my friend's bike to go get the plug spanner from mine. I pulled it and not surprisingly it was black and wet with fuel. I cleaned it up, plugged it into the cap, held it against the engine and gave the bike a kick. Nothing. I didn't have any other plugs on hand to try but by this stage I suspected something other than a bad plug. I got my dad to come pick my bike up on a trailer so I could diagnose the problem further at mine.
First I checked the spark with as new plug, still nothing. Next I tried sticking my thumb on the plug electrode and touching a ground while kicking it, and there were definitely pulses of voltage but they did feel rather weak, obviously not enough to jump the gap on the plug. I did all the tests in the manual, ie checked connections, coil and stator and they were all well within spec, so that only leaves the CDI.
Now for the interesting part. I have a Trail Tech Vapor speedo on my bike which I powered from the ignition side of the stator because of the whole tach interference thing when running from the lighting side (those who own a Vapor will know what I'm talking about). More specifically I used the green and pink wires coming from the stator, which also provides power to the CDI.
Posted Image
With the Vapor connected I got no spark, however with the Vapor disconnected I got a nice blue spark as normal. This really perplexed me because I've had the Vapor connected in this same way for 5 months without any trouble. I put the old spark plug back in (it sparked fine) and tried starting the bike, just backfiring like before. Put the new plug in and it sounded a lot more promising and eventually started, although sounding like it did at my friend's house. After running for a bit it started sounding half pie normal so I decided to plug the Vapor back in, the bike keeps running. OK, now I'm confused. I killed the bike and see if it'll start again, it does on the second kick. I took it for a spin and it seemed perfectly normal, pulling just as strong as it always has.
The next day I tried starting it again. On about the fourth kick it started and ran normally for about 3 seconds, then died. This is very uncharacteristic of my bike, if it starts with the choke on, it'll stay running. After it stalled there were no signs of it wanting to start again, not even backfiring.
So what's going on? Is my diagnosis correct of a stuffed CDI? The symptoms seem to fit but I'm just wondering why the Vapor would make a difference. Could having the Vapor connected this way somehow stuffed my CDI? I'm looking at getting the Vortex X10 but would like some of you guy's input before I fork out the NZ$600 for one.
Thanks for any light you can shed
Leo

  • WR_Dave

Posted April 26, 2008 - 05:12 AM

#2

This is almost an identical scenario from a few years back on my '02 WR 426. I finally gave in and bought the Vortex X-10 CDI box after speaking with Richard Muurling , who manufactures them.(just across the strait from you) His explanation was that the stock CDI failed and went into a default mode , which has the timing map severly retarded from normal. As soon as I installed the new CDI the bike ran better than it ever had and the adjustability was amazing. I also went through the entire fuel system many times with no good results. I think that the stock mapping is coming in and out causing your issues. Keep checking ,but I suspect you are looking at a new CDI. The Vortex is less money and easier to get than a factory stock unit. WR Dave.

  • Alternative

Posted April 26, 2008 - 05:47 AM

#3

Thanks Dave, I read about your CDI failing a while ago and when my bike didn't spark at my friend's place it's the first thing I thought of. What I don't really understand though is why having the Vapor plugged in or not made a difference. The Vapor uses shit all power, so why would this influence the ignition? Other than a stator problem the only thing I can think of is the capacitor in the CDI has half died and still works when getting all the juice, but fails when the Vapor sucks some power. Trouble is I don't understand how CDI's work so it makes it a bit difficult.

  • William1

Posted April 26, 2008 - 06:05 AM

#4

You should not have the Vapor connected to the stator!!! I am surprised it worked very well as the dwell from the staor is so long.

If any place, only one (the red) should go to the red wire (the black to a good ground) on the pickup coil. I have found the signal there is a bit weak so I do not reccomend it.

Remove both from the stator wires. Connect the black to a good ground. Connect the red to the ignition coil hot.

  • WR_Dave

Posted April 26, 2008 - 07:41 AM

#5

Sorry I'm not familar with the vapor set up, but it sounds like William1 has the right answer. The CDI takes the programmed spark mapping (the reason we all cut the grey wire to get to the YZ map) on your bike and compares it to the RPM of the engine relative to the TPS throttle position signal to create a 3D map that is infinetly variable. IE: high RPM with not much TPS signal(closed throttle) would tell the CDI to retard the timing and lower RPM with a large TPS (throttle open) signal would tell the CDI to advance the timing to get thedesired acceleration. The CDI takes all this info and decides when to fire the spark plug coil. Cliff notes version, but hopefully you get the idea. I would also disconnect the neutral switch coming up the front frame tube and be sure your coil ground is very clean with good contact. Richard Muurling <richard@vortexcdi.com> Talking with this man will likely tell you alot of things you are asking for info on. Good Luck !!! :thumbsup: WR Dave.

  • Alternative

Posted April 26, 2008 - 03:52 PM

#6

You should not have the Vapor connected to the stator!!! I am surprised it worked very well as the dwell from the staor is so long.

If any place, only one (the red) should go to the red wire (the black to a good ground) on the pickup coil. I have found the signal there is a bit weak so I do not reccomend it.

Remove both from the stator wires. Connect the black to a good ground. Connect the red to the ignition coil hot.


From what you've said, it sounds like you think I connected the tach to the stator, I didn't, I have it connected as you stated at the end of your post. The wire coming from the stator in my pic are for power to the Vapor, and on MX bikes (with no lighting coil) this is how Trail Tech suggest you connect it. I did try connecting it to the lighting coil instead but the regulator or something interferes with the power signal which makes the tach read something like 18000 rpm the whole time (don't ask me why). So I figured I'd hook it up to the ignition side like MX bikes, and this has been working fine for me for 5 months, so why now would it decide it didn't like it?

  • William1

Posted April 26, 2008 - 04:01 PM

#7

Ah, sorry for the mis-understanding.

If the Vapor is not connected, bike runs fine, correct? If so, I cannot imagine it is a CDI problem. Could be for some reason the Vapor is drawing too much current, with not enough left over for the CDI to fire.

Being a Vapor can run on AC too, up to 400 volts, did you try it connected to the lighting coil BEFORE the regulator/rectifier?

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  • Alternative

Posted April 26, 2008 - 05:28 PM

#8

If the Vapor is not connected, bike runs fine, correct? If so, I cannot imagine it is a CDI problem. Could be for some reason the Vapor is drawing too much current, with not enough left over for the CDI to fire.


With the Vapor disconnected I got a spark and did eventually get my bike started with a new plug. However after it was running I plugged the Vapor back in and it continued to fire. I then killed the bike and tried to restart it, which it did easily, therefore obviously now sparking with Vapor connected. I think possibly the CDI isn't producing the same spark energy as it used to, and now having the Vapor connected sucks enough power to influence the spark.

Being a Vapor can run on AC too, up to 400 volts, did you try it connected to the lighting coil BEFORE the regulator/rectifier?


The regulator (426s don't have a rectifier, they run on 12VAC) is in parallel with the lighting coil so there is no way of connecting the Vapor "before" the reg.

  • WR_Dave

Posted April 27, 2008 - 05:56 AM

#9

As I said before, I had exactly the same symptoms, minus the vapor, and it went n for a few weeks while I was trying to diagnose the problem. The trouble is that the CDI would give correct voltage and timing to the spark plug and then it would take it away intermittently. Finally the bike wouldn't run correctly under it's own power and I was forced to ride a freinds buddy bike KX250 for a weekend :thumbsup: . Installing the new CDI corrected all the problems instantly. I'm not saying this is the 100% solution, if you can find someone willing to loan you their CDI box off of a similar bike you can get the diagnosis done fairly quickly. Just offering the info on what cured my problem, which I hope is what TT is all about. Good Luck -- WR Dave

  • William1

Posted April 27, 2008 - 06:49 AM

#10

With the Vapor disconnected I got a spark and did eventually get my bike started with a new plug. However after it was running I plugged the Vapor back in and it continued to fire. I then killed the bike and tried to restart it, which it did easily, therefore obviously now sparking with Vapor connected. I think possibly the CDI isn't producing the same spark energy as it used to, and now having the Vapor connected sucks enough power to influence the spark.



The regulator (426s don't have a rectifier, they run on 12VAC) is in parallel with the lighting coil so there is no way of connecting the Vapor "before" the reg.


You might want to check and confirm the ignition part of the stator, perhaps it is weak or even an intermitant (I know, hard to check and confirm) short or open wire. You can at least confirm the output voltage is in spec and the resistance to ground it good. Sadly, with a CDI, all you can really test are most othe other parts. Only after they test as 'good' does it become realistic to look to the CDI. Normally, when a CDI dies, it first exhibits issues at high rpm, typically mis-fires. Rarely does it manifest as a starting issue.

Regarding connecting the Vapor prior to the lighting coil, you are inferring it is integral to the lighting portion of the stator. The Reg. is external so tapping into the wire coming from the stator should be no biggie.

  • WR_Dave

Posted April 27, 2008 - 10:02 AM

#11

Normally, when a CDI dies, it first exhibits issues at high rpm, typically mis-fires. Rarely does it manifest as a starting issue.


While I agree with Willliam1 on this statement, I am not a CDI ignition expert and after my conversations with Richard Muurling (who is an expert) he told me that the WR ignition defaults to a severly retarded ignition timing value when it fails. By fails I mean that the mapping in the ignition is no longer being followed by the processor in the CDI. So this holds up when I had my problem as the bike was extremely hard to start if it would and then it would backfire wildly when any attempt was made to rev the engine. I also agree that CDI's are the last thing to change, but this one has a bit of a history of failing. When I had my problems I tried every part, off of another bike except he wouldn't let me try the CDI in case I fried his, one at a time to see which one was faulty. Again, MY story ends with a happy ending after a CDI change. :thumbsup: WR Dave.

  • andymanmoel

Posted April 27, 2008 - 10:51 AM

#12

Hello All,
Does your bike have the coil built in to the plug cap? I had EXACTLY the same problem on my 05 WR450, I posted it on here and got all kinds of answers. All wrong for my problem. Took it to the dealers who had it for 2 weeks then one day it started for them and kept going for a month. Went to go out on it on friday and the problem was back!
After many hours swearing I found the problem!!! The plug that goes onto the coil pack had a bad connection on the neutral!!! You should see the one pin on the coil is black, If so take the plug appart and you will see one of the connections will be burned!
Hope this helps
Andrew

  • WR_Dave

Posted April 27, 2008 - 01:04 PM

#13

Seperate coil on the '02 426 unless it has been modded. WR Dave.

  • Alternative

Posted April 28, 2008 - 01:51 AM

#14

So this holds up when I had my problem as the bike was extremely hard to start if it would and then it would backfire wildly when any attempt was made to rev the engine.


This is exactly what my bike did when I got it running at my place, any attempt to rev it would only cause it to backfire and nearly stall. After a short while though it started running normally, at which point I plugged the Vapor back in. So I reckon it is the CDI, and for some reason when it defaults to the retarded timing, it no longer fires when the Vapor is plugged in. This is probably why I noticed early on, instead of it getting progressively worse as it did with you, as soon as it defaulted to the retarded timing it stopped firing all together.




 
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