Is the EX and XR motor the same size?

[Mike_Rides_Red]

I'm in the process of rebuilding my XR 400 into a 426 :D Since I have the bike apart I'm planning on replacing the timing chain and heard about a CRF450 chain fitting on 400ex. Does anyone know if the XR and EX engines are the same or if the 450 chain will fit on the XR 400?

Any help would be appreciated

[Pvt. Maggot]

I'm sure it would. I don't think the timing system on the xr and ex are any different. crf cam chain is the best way to go to. cheap and strong! :)

[jak1389]

when purchasing a crf450 cam chain, you must remember that only the 2002 model will work. the years past that have more links and will not work.;)

[Mike_Rides_Red]

I looked at servicehonda.com and the 02-05 cam chains are all the same part number. Is this right?

http://www.servicehonda.com/hard%20parts/off%20road/crf450r%2002-04/crf450r_04%20frames%20page.htm

[Mike_Rides_Red]

Also does anyone know if you have to take off the head to take off the cam chain or just the camshaft?

[2004exrider]

yes the xr and the ex are identical, except for the head gasket. i do believe you have to remove the head to take off the cam chain not 100% positive though.

[bigvforcer]

Take the cam chain tensioner off and you can get the chain loose and off the cam. I am not sure how to get the bottom part of the chain up. I haven't looked at the manual yet for the correct way to do it.

[44oEX]

yeah it can be done with the head still on the motor...the biggest problem is trying to get is to pass over the crank