Ignition Coil Upgrade on WR400F?

I stumbled across a post not long ago, where I thought the poster had mentioned in his signature that he upgraded to the newer style ignition coil on his 400. But I can't seem to find anything now. Anyone have any info on this? I have an extra new style coil for a YZ250F that I'd gladly convert and remove that big stock one if it's possible.


... is there any performance advantage?

If not, the ignition coil isn't so massive that I'd be concerned about swapping it out.

Nope, I just like to change things.....

i think tha 426 and 400 have the same part number of coils

No performance advantage.

However, there are less parts, no high tension lead to go bad, water is less of an issue. The reality of the mod is unless you have a spare COP (Coil Over Plug) laying about, it is not worth it unless you must have the latest technology in which case..... you should own the newest bike.

As always, you have a good way of summarizing it William.

Since nobody has responded with any specifics I have been trying to research it myself. The COP I have is from a 250F which looks to be a different part number than the 450F. The resistance values are different between the 250F and the 400F manuals. I plan to download the 03 450F manual to see if there is any difference between the 250F and 450f other than a part number.

Thanks for the compliment! :cheers:

You may find diameter/length is different too. Sometimes it will fit no problem, sometimes you need to try a bunch of different ones until you find one that fits. In some cases, the only difference is the rubber grommet or electrical connection..

My own experience regarding coil resistane values is they often are not a significant part of the puzzle and are more important to testing purposes. What I mean is basically a coil is a coil. But test values may help determine if a coil has or is about to fail.

Thanks for that info. So the part number difference, may be more of a size/length thing. I am a mechanical engineer, so the world of electrical is always a gamble for me. If I don't need to be concerned about frying my CDI or stator, then I'll just see if it fits physically. Looks like the wiring diagram leads are the same colors even.

Thanks again

I think you'll find nearly any COP will work fine. It is more of a dimentionsl thing.

CDI's are near impossible to cook. About the oly way you can damage them is by reversing the polarity of the wpower coming in (and even then, most have built in protection), applying way more voltage than designed for (most do have some sort of voltage managing circutry) and AC in stead of DC (and again, most have protection circuity.)

I have heard that if the coil is connected and the plug not grounded and you crank the bike, a very high vaoltage can build in the CDI and cause an internal arc. But I have never seen it happen. Truth be told, I have only seen on bad CDI in my entire life.

R1, R6, and Hayabusa coils will all work as well...cheap on e-bay.

If you get the coil make sure that the connector comes with it. That is the hard part to get really

Yep, I have the YZ250F harness too that has the connector I will pillage.

If you get the coil make sure that the connector comes with it. That is the hard part to get really

Not really...I had a parts guy at the local carquest find the Motorcraft part number. I posted it on the DRZ forum and somewhere on here as well. NAPA, CarQuest, and your local Ford store can all order them. Same connector they use on the stick coils on a 2.3 PZEV Focus.

I have an extra R6 coil laying around I can sell. I recently put one on my 426 and while it works pretty much the same it does look much better and is easy to get in and out of the head. My coil was bad that's why I went this route, much cheaper than a new 426 coil. Send me a PM if you are interested.

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