Yes it will fit... Same honda clone based motor so the mounts line right up. The issues will be with the exhaust,carb and oilcooler getting items bolted in. Any of the pitbike motors that are honda based clones bolt right in. Now if it's a klx motor those do not bolt right in different motor mounts
As Cam mentioned the brakes,tires and suspensions will need to be upgraded. You don't have to but for safety and if your gonna be going that fast I suggest it. Cam has done some great mods to get the stock front brakes to work better. There is a thread that a member did that is very detailed on what was envolved. I forget that member's name but I know he used a pitster pro 155z motor. Do a search or if I find the the thread i'll post a link.