Engine got extremely loud in an instant

[hoopfish]

Sorry in advance, I am brand new to this world. I have a 150cc 4 seater go kart. Bought brand new. No problems for a month until today while driving it got instantly loud and the heat from the engine’s heat was not flowing through the muffler. Noticed that the company I bought from didn’t have nuts that secured the muffler to the engine. So I did so. But the engine is still so darn loud. I noticed there was one tube that doesn’t seem to be attached to anything.
Again, sorry if I sound dumb, completely new and want to learn. Thanks if you can help!
Lindsay

 

[Dingocat]

Send pictures if possible. It'll help us figure out whats up. Sounds like the exhaust isn't put together right though.

 

[hoopfish]

https://1drv.ms/u/s!Aq62cMoCUHaDg3NNTNeALnDPsaoD

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https://1drv.ms/u/s!Aq62cMoCUHaDg3RPzoxtRcFUNzyQ

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https://1drv.ms/u/s!Aq62cMoCUHaDg3WdgI996vkO_NdJ

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Thanks for the response. The exhaust was perfect for the first month. Then at the drop of a dime, it was deafening loud. When I got home and check under, I saw that the plastic was melting under the part where the exhaust pipe wasn't bolted in. So I got bolts, bolted it in. But no change. I also noticed there was a black tube just kind of hanging out. I really appreciate your feedback and love to learn from you guys. This forum is already so helpful and seems so friendly. Thanks for helping the new kid.

Lindsay