One book arrived today day.

TWO STROKE PERFORMANCE TUNING by A.G. Bell.

Just skimming through it all the ideas I thought about are in this book. It's all there. It's well worth it if your looking for all the free performance upgrades. I'm going to get a degree wheel too. So everything is timed to the location of the piston in relationship to the ports. I think the 430cr, 390or are going to get special attention.

I was into degreeing the cam shafts to crank relationships in building drag race engines. There's no room for error. I'm A perfectionist. I built a 396/325hp using all stock Chevy parts I had 300hp @ rear wheels and 400hp@ engine estimated on a full body car dyno. I ported the heads and intake. She ran 12.85et 1/4 mile on the second run. That's a 4,050lb Impala c/ modified class. I did every possible trick.
Building engines is my forte.

i figured you would like that one. its pretty hardcore! geared more towards karts and roadrace 2 strokes but lots of good reading. tons of info on pipe building and theory.
no boost bottles tho..

2 boost bottle are better !

I was thinking that. Nitrous. Lmao. Imagine a 390 shifter cart. That's sick.

Back to the topic porting is a free performance upgrade with free horsepower. Just don't do it a little and think that's good enough. Follow the Husqvarna specs on porting. Arc the exhaust port. I raised it 1/8" in the center of the arc and 1/16" on both sides. I ported out the extra material in the port then polished it. Getting rid of the spent exhaust gasses faster/smoother allows the transfer ports to enter the new atomized mix faster. With a properly ported and tuned two stroke the rpm/ throttle response is right there the milk second you touch the throttle. There's no slow response it's there.

What amount we move the exhaust port up we lose some on the bottom end. You can port the exhaust port 1/32" on the left and right side and 1/16" in the center arc. I ported each bike to test what amount makes the biggest difference. Then I put everything I learned into the 81 Husqvarna cr250. She flew.

On a big bore the power band is much wider. Either way you port it will be ok. Remember building a two stroke isn't for the faint hearted. If your not a well experienced rider you must consider if you want to port it to spec or just clean it up. It does become a exciting ride.