Thoughts? I have balanced a ton of these and other single cylinder engines in the past, Horse power wise, go with the weights, it also adds to dependability. You may miss the gear for the track you are on and over rev the engine, it is a ton of weight moving around that crank and I have seen it (along with other people) break. Back to the HP, the reason (besides safety) to run a billet flywheel is to reduce the rotating mass, put one on and instantly you see the HP gain. My Mini's used cranks that were not syncros and I cut them even futher to reduce rotating mass. My cranks weighed less than 80 oz where a syncro crank with the ARC weights were over 125 oz. It gave a similar advantage of another aluminum flywheel on the engine.
The ARC weights are very close in balance, but engines like people are different, some of the cranks from Briggs are auful when it comes to haveing the same amount of weight on both sides and also on the length. So, I have posted on here several times how to check the balance of cranks, but you really need a lathe to even the sides of the crank and do it perfectly. But, you can easily get by if you are not turning over 6K without cutting on the crank and just checking balance with the weights.
And no, I do not balance anymore, time for someone else to step up and learn how to do it.