My problem is the bike won't idle and backfires . I changed out the pilot jet from standard #40 to #42 and got a new fuel screw tried to adjust to idle and one way engine got really hot where the exhaust pipe started to glow red and the other adjustments we did didn't do any thing at all plus when first got bike started first kick now it's hard to start even when the bike is warmed up . Got it now where it dont backfire as much when riding and letting off the throttle need help on this problem.

Let's focus on adjusting the air/fuel mixture. This adjustment can help balance the fuel-to-air ratio for both cylinders. Here are the steps you can follow:

Idle Screw (Air/Fuel Mix):
The idle screw, also known as the pilot screw, adjusts the air/fuel mixture at idle. It affects the fuel flow from the pilot jets (idle jets) into the carburetors.
Locate the idle screw on your carburetor. It's usually a small black knob near the choke.
Turn the idle screw to achieve the desired idle speed. Listen to how the bike sounds while adjusting it.
Note: Adjusting the idle screw shouldn't significantly affect the mixture setting.

Pilot Screw (Idle Mixture):
The pilot screw (idle mixture screw) fine-tunes the air/fuel mixture from idle rpm up to about 1/8th throttle.
To access the pilot screws, you may need to remove the air box and carb side cover.
The factory default setting for the pilot screws is typically 2.5 turns out.
Carefully screw each one in until it lightly seats closed, and then count the number of turns.
You can adjust the pilot screws to make the mixture richer (more turns out) or leaner (less than 2.5 turns).

Dual Carburetor Sync:
Since your bike has dual carburetors, it's essential to ensure they are synchronized.
Use a vacuum gauge set to synchronize the carbs. Adjust the linkage screw until both throttle butterflies are in the same position for idle2.
Synchronization helps maintain consistent performance between the front and rear cylinders.

Check Rear Cylinder Idle:
If the rear cylinder isn't running correctly at idle, it could be due to a partially plugged idle jet.

Consider cleaning the carburetors if needed. While it can be a bit of work, it's essential for proper performance.
If the issue persists, consult a mechanic or consider opening up the carburetor for a thorough inspection.

Remember to take your time and make gradual adjustments. If you're unsure, consult your bike's service manual or seek professional assistance.

Adjusting the Mixture Screws - VT750DC.com

Carb Cleaning on 03 spirit 750 ' Honda Shadow Forums

Carb Adjustments ' Honda Shadow Forums

Ok most likely cause for this is jetting (Carbi) and or the air / fuel mix screw set to rich - Well done for noticing though as no where near enough people read their spark plugs and make adjustments - they normally wait til bike don't work before researching?
Simplest and first option would be turn in your air/fuel mix screw quarter to half a turn in (clock wise) this leans the fuel mix slightly
Second option if still not helping from just screw adjustment is put the mix screw back to where it was before and change the pilot jet to a smaller size - the pilot jets have number stamped on them so once you have yours out look for the number and just buy new 1 or 2 sizes smaller (they only about $5 each) then of course go back to fine adjustments on your air/fuel mix screw to find the correct balance
You will very quickly know if your setting is to lean as result of adjustments as you will get back firing when rolling of the throttle if becomes to lean
jetting and air fuel mix adjustments can be annoying sometimes as you may need to go up a bit then down a bit then up again but take your time do very minor adjustments then check results and my tip is only ever change one thing at a time then record the change then test and record the result if you dont you will very quickly forget what you did, not know what to reverse if result was poor and if result was good you won't know exactly what made the improvement.
good luck mate regards Jamie

carb still not clean. sounds like low speed, pilot or fuel screw still not 100% backfiring because it is too lean. wouldn't ride too much uncorrected as it will make engine run hot

Hard to give accurate info with out seeing the bike with jetting but I would suggest take a reading from the fuel air screw if the bike running better with the fuel air screw in carbi at 2.5 turns out or more then definitely increase pilot jet up 1 or 2 sizes if you get the bike to run well between one - two turns out on the fuel air screw that is where your jetting should be
I wouldn't be concerned with main jet at all - it should be fine for wide open throttle unless you feeling power loss when you open it right up
also if you are getting backfire or popping when de accelleration that also hints toward lean pilot so a size or two change in pilot jet would be worth trying

melting spark plug is too lean. exhaust gas high temps caused by too much air. your oil to fuel ratio is correct, but your air to fuel ratio is not. adjust your needle clip position to add more fuel to the carb by lowering the C clip. this will raise the needle, giving you more fuel for the same amount of air. also check air filter element for tears.

The pilot jets are still gummed up. This jet controls the idle port and usually gets overlooked. To clean it the jet must be removed along and the adjusting screw as well. The circuit must be cleared of gum. For each individual carb, when removing the jet and the adjuster, count the turns then remount that number of turns. Now turn the adjuster screw 1/4 turn counter clockwise.