I have heard of this swap done quite a few times. is it hard or is it just a couple brackets being made specifically for this application.

 

What are the differences in the engines besides different cams and kickstart?

 

i think lower compression piston also. the ex is only 9.1:1 and i am pretty sure the xr is higher. but i think that is it.

 

i heard that the ex motor is the same thing as an xr motor just on a four wheeler frame.

 

I don't think its worth doing.

 

If you want my say, I would put a bigger motor in it if you are putting another one in. Like one out of a 650 or something if it would fit. then that sucker would fly.

 

Remember, kickstarters kick backwards so you either cut-off your right rear fender, take off the entire plastic to start it or develop a rear hinge for the plastic so that the plastic lifts in the front and tilts towards the rear.

Service Honda was gonna install CR250 engines in 400ex frames. All they had to do was re-engineer the kickstarter so that it kicked forward like the 250R's. Well I haven't heard of anyone with that hybrid quad yet so it must not be too easy. -RT

 

Also keep in mind that Honda beefed up the gears and clutch in the 400EX vs the XR - being someone who's ripped 3rd gear out of an EX, I certainly wouldn't want a lighter tranny.