like the title says im looking to put a CR250R motor into a honda quad frame so i can remake a honda 250R.....i know it might end up being more expensive then buying an old 250R but im doing it more for the mechanical challenge


which frame would be best to stuff the motor into?

 

Try some small quad frame like a blaster frame.

 

its been done hundreds of times and service honda has them ready for order. they use a 400ex frame and it fits beautifully. i would use that frame and order the mounts and such from them.

 

A 400EX frame is exactly the same as a 250R frame,but the CR250 motor wont fit perfectly.I had to use a swingarm from an older 250R when i made mine so the bolt would got through the back of the motor and the swingarm.Dont use any other frame besides a Honda one.Yamaha frames are weak,especially Blasters.

 

No matter what frame you use, i would strip it down and gusset it first.

 

Oh yeah,I just remebered that the 250R frames A-Arms will not work on a 400EX frame and vice versa.So I guess they arent exactly the same but they are pretty close,but i would still go with a 87-88 250R frame.

 

thanks for the replies guys


im gonna use the 400 ex frame since my 400 ex has a blown motor and i got a 250 dirtbike thats useless expept for the motor

teh 400 has a good deal of work done to it already, like A arms and stuff and a different swingarm so maybe i can get it to work

im gonna start stripping htem down soon and get some measurements and stuff

 

You will have to address vibration issues................

That motor is NOT exactly the same as the old fourtrax motor.
The 250R motors are counterbalanced, the CR is not.

You will have to use the motor mounts from Service Honda and do whatever they do to make the vibrations acceptable.

 

Ive got a 88 CR250 motor on mine and it doesnt vibrate at all,I have 2 more REAL R's and the truth is the CR motor is faster than them because of the power valve system.

 

thanks for the tips and heads up

i think i got a good solution for the vibration probs

n e other issues i should be aware of?

im using cad to check the frame for stresses and gusset it accordingly and ive got some mock ups of the motor sitting in the frame and the suspension set up