Hybrid?

[thebig450es]

Which engine would be most practical to swap into a 400ex frame? 250r, CR500, xr650r?

[HondaPohl]

They all have been done. None of these are direct bolt in's I believe. The 500 and the 650 would be awesome. I rode a 650ex and it was wild.

[CJM]

none are direct bolt ins, 250r shares a similar chassis to an ex but it still takes work. Also 2 stroke motors can cause excessive vibration

Id try for the 650 personally, talk about power :)

[finsteratv]

the 2 smokes like said above cause alot of extra vibration. but im guessing you could use somthing like rubber mounts to cut that down. the 2strokes im guessing would probably also be cheaper.
BUT a 650 would be alot of roosting frame twisting power :eek: not to mention FUN

[crownandmonster]

I've been thinking about a crf250r or crf 450r swap for some time now. Its just hard to justify spending over a thousand dollars on a running motor or 6-7 hundred on a blown up one to do the swap.

[thebig450es]

I was thinking a 400ex produceing an extra HP for every $100 , a 400ex maxes out at about 50hp. With a cr500 or xr650 60 hp is pretty easy to get out of them. Then $2500 wouldnt be to bad to spend on a swap

[PaRedneckRiders]

I sold my running crf450 motor for 500 just to get rid of the thing and i sorta kicked myself for selling it after i did but owell.
I have seen some with yz426 motors but i wouldn't do that keep it Honda, It will run better haha.