I am considering putting either a YZ400 or 426 in a 250R frame. What do you do for an exhuast and airboot? Can anyone convert a stock 250R frame so a yz motor will fit in it? What else is there to worry about? I would be extremely thankful of any help!

 

This months dirtwheels has an article on the YZ426F based quad that Tim Farr rode for the Pace Series (ans swept all 3 races!!). It was also based on an R chassis, so it can be done. Go to some back issues of last year and read about Kory Ellis's Yz400F based quad as well. Also based on the R frame, and I belive he won a race on it as well. I would love to build one myself, but in the mag, it said that to build one like Farr's, you would have to spend upwards of $25,000. WAYYYYY to much cash for me!

 

I was over at East Coast ATV the other day and they have two 400EXes with YZ400 motor and the look pretty cool. My sugestion would be to call Dave over at East Coast and talk to him about it. A new Arens frame with YZ motor mounts costs about $2000. Hope I helped.

 

I want to do the yzf400ex conversion!!!! I am gonna email East Coast and ask them about it!!! I am serious about this..
I will let you guys know what they tell me.. See ya
matt

 

If you want more power dont waste your money on that 426 motor. Put a nice four cylinder motor in. Some thing like an Yam EXUP 400 16 valve twin cam. this will put a nice smile on your face and you can roost your mates any time........

 

Already doing it with a YZ400F, I'm using a 400EX chassis cause they drop in without frame rail mods. You'd have to hack the R frame up allot to get it to fit in. I know some one that did that at first, now he has his in a stock 400EX chassis and he say's that the 400EX frame handles better and doesn't tire him near as much as an R frame... Also an Aerens YZ400 chassis cost's just about $3000 for the frame, swing-arm, and steering stem. A stock 400EX frame and sub-frame is only $600, I know a guy that makes very nice swing-arms for $350 and a stock steering stem is only $50. So I'm sticken with stock for 1/3 the cost, because my friend about got an Aerens chassis and he heard people were breaking them. Maybe they fixed them now, but I don't know. I do know I'm still on my stock 88 R frame and it's held up for 12 years now. Also I can buy allot of new 400EX frames for the cost of one aftermarket chassis, which is also going to eventually break.

Sickman

 

As far as things to worry about, one is you need to make an oil tank, or use something like a 400EX tank. Also, I have been speaking with EastCoast ATV and they said the stock 400EX airbox and boot work fine, you just have to move the box a little forward, which isn't hard to do. Also, the stock pipe will work if you cut the stock silencer at the taper, turn it, and then reweld it on so it goes straight. I am going to go aftermarket, but may keep the stocker around for trails if I need a spark arrestor and less noise. If you have any questions let me know.

 

sickman,
I emailed you about this the other day,,did you get my email? So your telling me the YZ will drop into the 400ex chaisis without doing the rail mods? That is awesome! So what mods do you have to make for the frame? Like motor mounts? WHat are you gonna do for the raditor? I can't say it enought, i am really interested on doing this conversion!! I really am. But do you really think this is worth it? I do but some people are telling me it isn't. But whocares. I figure i can do this for under 10k. One more question, what stock R parts will bolt on to the 400ex frame?
thanks you sooo much man!
Matt
COuld you please let us know how your project is coming along?

 

Thanks for telling us about the motor fitting in the 400EX frame. Before knowing this, I had assumed that a YZ quad was totally outta the question but now knowing this, I may consider it.
As for whether or not its worth it, I guess that depends on if the almost double horsepower of the YZ motor is worth it. They make more than a built 250R motor I hear, so I think it would be worth it. Since the 400EX and 250R are so much alike, I think that you could use the 250R plastic and mount the radiator as you would on an R. It might take a little welding, but should work out ok.
Good luck, and let me know how it goes,

 

Sorry, I tried changing the e-mail to the on I look at all the time Sickman_80@usa.net. No stock R parts realy work other than axle, hubs, brakes (If you use stock R spindles or use 400EX spindles with new brake mount Balwin Motorsports makes, and handle bars. The rest you must use 400EX parts, and yes I'm going to use a 250R radiator. The mods needed are to make the radiator mounts, oil tank, and new motor mounts. If your interested, I know a guy who makes nice swing-arms for $350.

Adam

PS: The guys that say its not worth it are afraid of getting beat. The stock YZ400 puts out twice the power that a 400EX does.