retro, yes, there are ways. the main things are, don't press the entire crank all the way together, just enough on the main axles to keep it togehter, and it must be aligned straight, with the phasing correct. then, if you make crank pins like I did, that are removavble, that you can set the bob weights onto, that's the way to do it. Of course, it goes to say that all the crank pins that will go into the crank need to be balanced to the same weight, big ends of rods, bearing cages, thrust washers, big, then small ends, and overall of the rods, and the top ends just like we do in a 4 cycle engine, bike, car, whatever.
The only things that get balanced differently are rotating assemblies that use a balancer shaft, and airplane engines, as they have a floating counterweight. That is the clank in them as they reach almost full loss of rotation when they are shutting down.
And, keep the piston clearances reasonable, don't bore them to already fully worn out clearances, makes for a better engine, less vibration, noise, more power. I have found that piston clearances can be set a lot closer with most pistons, and, haven't ever had problems doing so, in any engine I have built. I can't remember all the people with noisy engines I have asked what bore clearances they had, but all of them were significantly looser than I would have set them.
The first factory H2R forged pistons were so bad, we'd break a set in in two laps, they'd fully collapse the skirts in the next 3 laps, we'd go about gearing and jetting, then, for the next day, we'd put a new set of soldiers in. On race day, we'd new piston between the last testing session and the race. The Yamaha stuff I worked on, and Salaverria's Aprilia, we'd set a new set of pistons up for one race weekend, then, run 'em all weekend, then pull apart between races, new rings only most of the tme, and go around again the next race weekend. They'd go a good two full races on one set of pistons. The Yamaha and Aprilia pistons were pressure spin cast, they worked very well.
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