i no a yz426 and a crf ingine will but n e uthers that will fit good

 

250r motors.

 

Anyone know if the xr650 motor would fit? Would vibrating be too rough?

 

you may have to add a couple rubber engine mounts on the frame and i think you have to change a couple minor parts but other then that it fits.

 

will the ktm engine fit cuz it fits in the 250r
eny one want to buy my 400ex engine or trade

 

would a ds650 engine fit

and if i stuck a dirt bike engine in mine would the gears hold up to the extra stress

 

I wouldn't reccommend any kind of dirtbike motor, the vibrations will not make it rider friendly. Motorcycle engines aren't counterbalanced so they vibrate like crazy in an atv frame. But yes the gears would hold up fine, but you made need to play around with your sprocket sizes.I would really look into maybe a 250R motor. You could pick it up relatively cheap, and it would be a lot faster than your 400 motor. And because its counterbalanced there won't be any bad vibrations. Just my 2 cents.

 

i want a 4 stroke though.

and would a like 250 4 stroke dirt bike engine be faster in my 400ex than having the 400ex engine in it.

cuz i think 85cc dirt bikes make as much power as a 400ex but not 4 shure.

 

No i don't think it would be faster. But if your heart is set on a 4-stroke, maybe just get the 440 kit for the 400 motor. That would be the easiest and cheapest way to get more power. Because you do't want to put a dirtbike engine in if you plan on riding for extended periods of time. And is there any reason you're against the 2-strokes? They are cheap to build power with.

 

i like the smell of 2 strokes but hear they blow up easier and nead to get rebuilt sooner.

440 kits for 400ex blow head gaskets all the time and need to get rebuilt once a year.

i am trying to get a race ready 250r and put a diffrent engine in it but first my quad has to sell. or if my engine sells first im going to buy a diffrent engine for it.