I have a non-hemi predator 212 and I'm looking for some upgrade advice. I have a 22mm Mikuni carb along with the curved intake manifold and angled air filter, racing spark plug, 18lb valve springs, billet flywheel, superbox exhaust(without muffler), stock cam, and stock rod. With this set up, what length arc rod and what cam should I get and what size main jet do you recommend? Keep in mind that I will not be upgrading from the dished piston to the flat top. Also, if I were to use a gx160 head, what size arc rod would you suggest? The engine will be going on a baja warrior
The options from ARC on the predator rod is the length. You need to remove the head and measure the distance from the top of the piston to the deck of the cylinder at TDC. If it is closer than .020 you would probably order the STD rod, If it is greater than .020 you would order the +.020 longer rod for Max compression.
^ And again, remove the head and see how far your piston is below deck @ TDC. That will tell you how far over stock length (if any) you can order. You listed parts but what kind of riding do you do? It's really hard to pick a cam based on that information. If I was going inside that engine to do a rod, I'd change over to the hemi flat top piston and order my rod from there.