I did this once. NP I took my Harmonic ballance tool kit and found the next size up from the bolt that was in the crank. I got a tap for that size and taped the crank. I had to go to a speciality bolt place where they make bolts to find the hardened one I needed. It was so cheap they just gave it to me. I also got a thick washer that was hardened. Never had a problem with it after that.