Hi, I'm not actually new here, just setup a new account with my new email. I have a 01 660 that I am building with a +4mm Hot Rods Crank and 102mm big bore. After sealing the two crank cases and aligning the primary drive gear with the driven gear on balance, when I rotate the crank it crosses paths with the balance. So I tightened the nuts holding the balance and crank and still same issue. I thought about grinding some material of balance but when you look at the collision between the crank and balance, I would need to take off a noticeable amount of material. The other thing I tried and worked was advancing the balancer 20 degrees. Now the whole assembly works perfect. Ill provide a video below but basically I am wondering if this small advancement in the balance gear is okay. After all, some people run without them. 🤷‍♂️ Thanks for any help, I really appreciate it!

VIDEO:

 

Don't know the 660 at all, but the 350 motor has dampers in the middle of the balancer gear and you can assemble the damper six wrong ways, which throws the timing out, my guess is your machine must have a similar set up. Any imbalance is going to make the whole bike vibrate at a certain RPM.

 

You are the best!! Literally don't know how I could have skipped over that considering I inspected the dampers. I actually thought the outer gear was keyed so there was no alignment with the gear assembly lol. Not too proud of myself for something this basic haha. I'm a good mechanic but there's small things likes this I forget about. I need an assistant lol.