I was at pismo to day. I saw 400ex with dirt bike 450r in it. It was fast and looked like a nice dune bike. Does anybody know how do this .

I SAW ONE ONE TIME AND I ALMOST STARTED LOOKING FOR THE CRF MOTOR.... IT WAS CLEAN, BUT I NEVER HAD THE MONEY TO DO IT....

Sand HO has a buddy who did this exact thing not sure any specifics maybe he will chime in.

Unless your an excellent fabricator, buying a trx450 and doing pipe, air cleaner, jets, and maybe cam mods will be just as cheap and much less of a headache. This was a popular mod with YZ426f motors in laegar frames for mx. The thumper motors gave better traction and horsepower than the 250r motor most were using and you saw several of the top quad riders having these bikes built. They were very sucessfull at the time but with the availability of the trx and YZF450 quads, it's the long way to a good quad now.

Service Honda is or was offering the 400ex with a CR250r motor in it, basically a new school trx250r. I haven't heard much interest in the bike since the thumpers came out.