Weak spark on Hard starting '05WR. CDI?

12 replies to this topic
  • dugabrams

Posted October 20, 2007 - 08:31 PM


Hey guys, my bike runs great, but recently Ive been having a hell of a time starting my '05 wr450. It will no longer start with the button and now takes way too many kicks to start (sometimes it won't start at all). This is a problem that has gotten much worse over the last 3 or 4 rides and the weather hasn't changed much. I checked the valves and they are in spec. This bike has been professionally converted into a dualsport and uses a Baja designs rectifier in place of the stock unit. The stator has been modified. It has a yz ex. cam which doesn't help it start as well. I have checked conections and everything seems to be in good order. The battery is brand new.

Using my sons "03 wr250 , I think I have isolated the problem to a weak spark. When I test for spark on my 450, all I get is a single spark when I hit the starter button while grounding the plug against the motor. When I do the same thing on the 250,(450 plug and coil) it repeatedly sparks bright just like you would expect. I tried the 250 coil and plug on the 450 and same thing, a single spark, then nothing. The plug is gapped correctly. From what I have been able to come up with searching this forum, I may have a bad CDI.

Does this sound like the problem? Can I use the 250 CDI to test? If I need a new CDI, what years are compatable?

Any help :crazy: would be greatly appreciated.

  • Thumper_Bloke

Posted October 20, 2007 - 10:19 PM


Well, you narrowed it down pretty good. Maybe you can send you 05 CDI to me, I have a 2004 (ignitions are the same), and i can test it for you. PM me if you want to do this.

BTW - your starwars avatar cracks me up!

  • dugabrams

Posted October 22, 2007 - 06:38 PM


Anybody else have something to add. I could really use some input.

  • andy666

Posted October 22, 2007 - 08:27 PM


Check your grounds .....

  • Thumper_Bloke

Posted October 23, 2007 - 09:52 AM


Dude, send it to me, I'll test it directly on my excellent running '04-WR450. Where are you located?

  • clark4131

Posted October 23, 2007 - 07:00 PM


Regardless of the professional installation, Baja Designs has had a chronic problem with their WR kit, namely with the stator. Last I heard, they had been working on a concrete solution, but I haven't heard what the progress has been. Also, I thought they had pulled all their kits off the shelf until the problem could be recitified and the fixed kits could be marketed. With that in mind, when was the kit installed?...SC

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  • dugabrams

Posted October 25, 2007 - 08:39 AM


It was installed about 18 months ago. The problem surfaced about 3 months ago.
Help me out here, the stator is some type of alternator so wouldn't this simply cause a problem in the charging circuit? I'm not positive that the charging system is working but regardless of that, the battery is fully charged and I still don't have the proper spark. Do the Baja kit problems have the ability to affect the spark and or CDI? Should I contact Baja and ask them? Should I try the stock rectifier and see what happens?

  • dugabrams

Posted October 25, 2007 - 12:20 PM


Major Discovery!!!!

The stator has come lose from inside the stator cover and got seriously chewed by the assembly. It's toast and there are metal shavings everywhere.

Other than replacing the obvious parts, are the shavings a big concern?

  • beezer

Posted October 25, 2007 - 12:38 PM


That happened to a buddies WR and his shavings were all copper so nothing got hurt.

I would clean the oil strainer and change the oil and filter after each ride for a while.

  • Thumper_Bloke

Posted October 25, 2007 - 04:34 PM


OHHHH ! good find. Well, not so good, but at least you know what the problem is now. I had a stator come loose on a KFX400 quad. Copper everywhere. I flushed the engine with kerosene and compressed air. Then started it up, and changed the filter and oil afer the first warmup. Cut open the oil filter and stretch out the "accordian" to see how much was trapped.

  • dugabrams

Posted October 25, 2007 - 09:57 PM


No copper, just lots of steel from the center of the stator. I'm hoping that the magnet that is the magneto has kept all the steel shavings local to just the stator area. I guess the filter will tell the story.

  • dugabrams

Posted November 02, 2007 - 07:11 AM


Well, my baby is back on the road! :worthy: The new stator restored the spark. I would think you could still get spark without a stator if you had a fresh battery, but one of the wires was probably grounding out against the stator cover. I used longer bolts and red locktite to insure it won't get loose again.
My worries about stator metal polluting the engine are very valid. :worthy: I didn't find anything in the oil strainer, but there are lots of fine metalic shavings in the filter.
Other than changing the oil and filter until I quit seeing metal, should I do anything else?
Thumper Bloke, thanks for your offer to test the CDI.

  • 2grimjim

Posted November 04, 2007 - 10:07 AM


Did the stator bolts back out?

I've seen the bolts for the starter gear (bolts that go through the flywheel and into the gear on the back side) back out and tear the stator apart as well.

There's a pulser coil that's part of the stator and tells the CDI when to fire. If that's tore up, good battery or not, she wont run.


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