2006 wr450 red hot exhaust plus rough idle plus backfire on deceleration

If your Yamaha Vstar 650 is backfiring when decelerating, it could be due to a lean fuel mixture or an air leak. One solution is to adjust the air/fuel mixture screw on the carburetor, but before doing that, it's recommended to check and address the following:

1. Inspect the exhaust system: Make sure there are no holes, leaks, or loose connections in the exhaust system. Fix any issues if found.
2. Check for air leaks: Inspect the intake manifold and carburetor boot for any cracks, loose connections, or air leaks. If you find any, fix them and ensure a tight seal.
3. Clean or replace the air filter: A dirty or clogged air filter can affect the air/fuel mixture. Clean or replace the air filter if necessary.
4. Check carburetor jets: If the bike has been sitting for a while or the carburetor hasn't been cleaned in a long time, there might be debris or clogs in the jets. Remove and clean the carburetor jets.
5. Adjust the air/fuel mixture: Locate the air/fuel mixture screw on the side of the carburetor. Gradually turn it clockwise or counterclockwise (usually clockwise) until the backfiring reduces or stops. Start with small adjustments, and make note of the screw's original position in case you need to revert the changes.
6. If the backfiring persists, it is recommended to consult a motorcycle mechanic or Yamaha dealership for further diagnosis and assistance.

it sounds like its starving for fuel, when it runs lean you will get backfires and if its running rough then it may be starving for fuel at idle. Try adjusting you mixture screw and see it the engine will smoot out. Your carb my be dirty and not allowing enough fuel through it.

BACKFIRE OCCURES DUE TO RUNNING TO RICH AND EXPELLED UNBURNED RAW FUEL EXPLODING IN TAIL PIPE.WHEN COOL AIR HITS IT FROM DECELERATION THE ENGINES SUCKING IN MORE AIR CAUSING IT..A LITTLE BACKFIRE IS NOTHING TO WORRIE ABOUT IF ITS A CANNON GOING OFF YOU NEED TO ADDRESS IT..THE FUEL TO AIR MIXTURE ISNT CORRECT..I WOULD LEAN IT OUT ALITTLE.

check the lambda sensor in the exhaust system
ecu fuel mix sync

I would suggest not making any changes until you find out the problem. especially if the bike was running ok prior. Was the bike sitting for the winter? did you use any fuel stabilizer? Change fuel including draining carbs. Check your air intake passages for spider webs, any mouse nests,... check air filter. change your spark plugs , especially if they look black. The condition of the old spark plugs will tell you a lot. Black indicates running too rich. Whitish or next to nothing indicates too lean fuel mixture. Tanish color is perfect. Start with the simple fixes before dropping money into her

Exhaust leaks near the exhaust port can draw air into pipe on deceleration and detonate any unburnt fuel leaving engine, causing backfire and high temps.
An overly lean fuel mixture on the engine can make decel backfire worse too.