03 mountain cat 800 efi to 900

[HANDSOME]

My buddy has this 800 cat and I gave him my old 900 efi cat engine with a bent rod and busted case. What would he need to change fueling wise if he put the 900 jugs on the 800 ?

 

[Arcticatdan]

If it is efi put in a timing key backwards and a all will be good. If you have the ecu should work with nothing. When we did it ecu were hard to come by. If you have more questions PM arcticatwill he is my son and we did it fir his sled years ago.