YZ400 to wr400 flywheel conversion??

Has anybody done the conversion from yz400 to wr400 flywheel ? The yz400 power-hit is kicking my butt and I am considering the change...Or, I might just do a 10-14oz bolt on...Anybody have some experience with toning the power down so I can trail ride this monster? The bike is blindingly too fast for me! 47 year old old fart...



I feel your pain. After NEVER owning a bike, my first purchase was a 426 :applause: Now as the song says, "what was I thinkin'"! It was a deal that I could not pass up. I to, am looking for a way to mellow it out a bit. It does have a weighted flywheel, and a buddy says that makes life much better. I am looking at going "clutchless", if that is possible. Let me know how your flywheel is working after you do it, if you could. One of the things I have noticed is that the more you ride it, the better it gets. So try to get used to it. But I am going to do some more searching on here to figure a way to make it more "old guy/beginer friendly". Craig

Tell you what happened. I have been riding my TTR-225 for about 2 years...no problems, just not enough punch. So I find this YZ400f, '99, e series WB, great deal $2100 in Nor-Cal. First ride, crash, dislocated ankle, broken tibia, cracked heel on tibia. Throttle blip to get up the face of hard pack and spin out on loose flat section. Went sideways due to wheelspin and the front of my boot catches the ground and gets dragged under the peg. Trauna unit, ambulace ride, screwed up Memerial Day holiday...So, the power comes on too fast, and you get wheel spin and crash...

So, I want to basically de-tune the bike...I was thinking, stock exhaust and heavy flywheel...I really need some help on what to do to accomplish this. As I understand, the yz400 motor is the same as the wr400, with the exception of the flywheel and the exhaust cam timing, one tooth...




Yes, a 99 WR400 flywheel/ignition coil will retro fit to a 99 YZ400. You do however have to buy both the coil and flywheel, as the unit is meant to go together. It's about 275 at a yamahahaha dealer. This will however, get you 100W of lighting capability should you choose to make your YZ streetable. It does nicely for the stall prone-ness of the YZ as well. Once you get the pieces, go to electrexusa.com and read the tech tips to learn how to "float the ground wire" on the coil so it'll run. It's easy with the directions and a soldering iron. It aint cheap but it works really well.

Dont even sweat the timing issue, it'll run great.

If you have the cash a rekluse clutch (see TT store) will alleviate the clutch lever and is pretty groovy for the woods. I've heard it makes the low end more managable as well.

You could always sell it and buy a YZ250F, little lighter lot more tame.

PM me if you have any questions, i did it to my YZ400 for the Dual Sport use about 4 months ago.


FMFQ2, powernow, Pro circuit susp, Pro Tapers, Street legal missile!

purchased my 99 yz400f 8 days ago & took it out for my first time today, loved it! The torque of the motor is so nice :eek: Unfortunantly I was on a motorcross track & not the woods so I will have to wait for another day to see how it does in the woods. Been away from offroad bikes for 14+ years now :applause:

Anyways, if the yz400f is to much power why not just downsize to say a yz250f? You would have a bit less power & also a bit less weight to throw around, might be easier to deal with??

Thanks for the replys, Has anyone riden a WR250f? There are a number of them for sale at about $3000...Is there enough punch?

I love the suspension on my 99 yz400F, Enzo modified, front and rear. The TTR-225 just didn't cut it...Heavy, poor suspension, old school motor...Hey, but I didn't get hurt either...Anyway, what about a 2001 WR250F? Thinking very seriously about it!


Give your 400 a little time. Unless you are 5'8 or less and weigh under 150lbs, you should be ok on it. I'm 5'10 170 and I'm fine, It took me about a month (5 rides) to realize that this is a totally different animal. Whereas a 2smoke is ok with being forced around, riding this thumper is more like a partnership, if I ask nicely its happy to comply, if I try and force, it usually puts me on my head. Especially in the throttle department. Once you learn to factor in the extra weight and the nature of a 4 stroke you'll be happy. Just approach everything in one gear higher (3rd not 2nd) than you would on a 2stroke, the over rev on these is a killer. The extra weight can be nice too. I routeinly plow through whoops and braking bumps that used to skip me all over.

That's my .02. I thought the same thing when i bought mine but now I love it, I wouldnt trade it for anything, except maybe a WR400, I'd love e-start. :applause:


FMFQ2 powernow ProCircuit susp Pro tapers 12/48 Street legal missile!

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