DO NOT ATTEMPT THIS YOURSELF !!!!! im betting money you dont have the right tools for the job. (press,crank trueing stand etc)
go to your local shop and ask them if the have a machine shop recommendation for doing this job. they may say that they just buy new , if thats the case move on and ask elsewhere.
good luck
Unfortunitely, this is one of the things that we really can't service on our bikes. In fact, It is probably the only thing that is not serviceable by someone other than a machine shop on a MX bike.
Over here , the cranks and rod kits are much more expensive , and the price per hour is way more than in the US. Most shops charge something like 50 $ , that is for installing the rod kit and aligning the crank again.
Wiseco cranks are less expensive than most stock ones. Supposedly, they are very good too. It's probably the safest option if you don't have access to a good machine shop.
I asked my dealer why it always costs around 50 $ , and he said : " Sometimes it takes me 10 min , sometimes up to an hour ".
I have done it myself on small 50 cc moped engines , it can take up to 2 hours in a good workshop , but without the real tools for the job.