Honda 250R Motor (OR) CR500 Motor???

[ghawkman]

I want to take my 400 motor out of my 400EX and replace it with either a 250R (86) or a CR500 motor. Which is better? More reliable? Can the 400EX frame handle the CR500 motor? What is the best year for the CR500 motor?

I am done with the 400 motor. After riding my (86) 250R ATC and a friends (03)Basnhee, I want a 2 Stroke again, but in my 400EX frame with my awesome suspension I added.

Will this be a pretty easy conversion?

Thanks for all the info....

[YZROOSTINYA]

your better off with a 250r motor over a cr500 or even a cr250 motor, dirtbike motors are NOT counterbalnced which put a lot of vibration into the frame causing cracks.

it can be done and has been done but just something to keep in mind,servive honda is doing this set up as we speak(cr250 motor in 400ex frame)

i would see if you could hook up soem type of anti vibe material between the mating surfaces of the motor and frame such ans rubber coated spacers or sumpin to help with the vibes

[250rtone]

I agree, my bud just put his 99 cr500 engine in his 88R and it vibrates like a S.O.B!! Goes like **** though! It would be very uncomfortable on long rides.

[AndrewRRR]

Everyone I've talked to who has done a dirtbike motor in a quad frame (especially a CR500/ 250r swap) swears up and down they will never do it again. Even when they rubber mount the motor. It just plain vibrates too much. You can't ride it long before your arms go numb and you get a headache. lol
A 250r motor would be a good way to go if you want a 2 stroke, but I have a feeling in the end you'd rather just sell your 400ex and buy a 250r instead of trying to do the fab work to get a R motor in a EX chassis. It will definately take welding, cutting, lots of measuring, and probably many, many swear words!
If you want more power than a stock 250r has you can go with porting, a big bore, or get extreme and do something like a pilot jug, MAC racing's CR500 top end conversion (http://www.macracinginc.com/cr500_worksheet.htm) , or go really nuts and do a Rotax 440 swap. It's all measured in cubic dollars. How fast do you want to go? ;)