Hi, Anonymous it should be noted that the "AIR FUEL" mixture screw adjustment "ONLY" manages your idle and has no effect on any other circuit also any intake leaks must be repaired before the A/F adjustment procedure can be performed otherwise you will never obtain a proper idle and you will waste a lot of time chasing the impossible. The A/F mixture screw's purpose is to fine-tune the fuel charge entering the combustion chamber. The following applies to both 2 and 4 stroke engines:
1. The mixture screw may be sealed at the factory with a Welch Plug please review the following video for removal. https://www.youtube.com/watch?v=wAXcksgvDkM
2. The mixture screw manages a range of 3 complete 360-degree counterclockwise turns from the bottom/closed position.
3. The mixture screw should have a spring and o-ring for tension and sealing integrity.
4. Turn the mixture screw clockwise until it gently bottoms out, this makes the fuel charge very lean and the engine should not idle if it does then the pilot/idle jet is too big and needs to be replaced with the next size smaller.
5. Turn the mixture screw 1 and 1/2 turns counterclockwise to establish a baseline for starting the engine.
6. To fine-tune the idle circuit, adjust the mixture screw 1/4 turn in or out to achieve maximum idle RPM, wait 15 seconds between each adjustment for the idle to settle.
7. Never go past 3 full turns out this will make the fuel charge rich, foul plugs, and produce black smoke out of the exhaust, if the engine RPM keeps increasing past 3 turns the pilot/idle jet is too small and needs to be replaced with the next size larger.
8. After achieving maximum idle back out the mixture screw another 1/8 of a turn then adjust the throttle cable idle stop screw to 950-1050 RPM.
9. This procedure works great on 99% of all engines, for the 1% that demand a more robust throttle response on aftermarket monster fuel delivery systems additional tweaking outside the box may be necessary.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day. https://www.google.com/search?q=Carburetor+adjustments+1983+Husqvarna+CR+430&tbm=isch&source=univ&sa=X&ved=2ahUKEwjC09ybpd3lAhVBuVkKHV61C4oQsAR6BAgIEAE&biw=1440&bih=757 https://www.youtube.com/watch?v=nxwZ3sOI0Z0 http://docs.husqvarnaoutlet.com.cdn.wavenetworks.com/repair%20manuals/1987-1988%20-%204%20Stroke%20Engine%20Repair.pdf https://www.bikebandit.com/husqvarna-motorcycle-parts http://mybikemanuals.com/husqvarna/
Piston rings could have snapped and is making it hard to move piston in barrel
I wouldn't recommend using bike till you check piston out as you could damage header of engine and may need it replacing if you damage it too much.
Those voltage numbers are horrible. Just sitting on your workbench, the battery should read at least 12.8 volts. And without the gear turned on, the voltage at idle should be above 14 volts. I have a hunch you're going to find the voltage regulator and/or bad connections in the brown coupler are the culprit, but I suppose it wouldn't hurt to check the alternator.
Unplug the brown coupler, set your meter to read AC volts and probe any two of the yellow wires in the harness side of the coupler. Rev the engine to 4000 rpm and you should see at least 60 volts AC. If you consider the three yellow wires to be A, B, and C, you'll need to perform this test on the pairs A-B, A-C, and B-C. Good luck.
It takes SAE 20w in the transmission, They say a 4%mix for the gas oil mix and 94 octane , I have a 390 and run synthetic oil and run at 50:1 never had any problems. 4% is 32:1 , But with the new oils go for the 50:1 is better , You will not gum up the piston ring.