I'm not 'on the case' on this post but just reading #34--if it won't shut down i've seen the idle speed control rod on those early carbs [that goes down through the slide] get bent & the minimushroom on the bottom gets caught & hangs the slide up a bit. Number 18.
www.partzilla.com/catalog/yamaha/motorcy...a-80-mg1t/carburetor

Thanks all for the help. What type of cleaner should I use on the carb with my ultrasonic cleaner? I am planning to use pine sol.

Pine Sol seems to work good.  If I remember correctly it might darken the aluminum but that shouldn't hurt anything.  Make sure to completely disassemble and don't put rubber or plastic in...  like the choke plunger probably has a rubber seal on the end.  Pine Sol might ruin that.  

Hello @Mark,

I ordered the suggested needle/chamber part number from partzilla for my bike and it looks different than the original in my carb. In the image the top part is the original and the bottom is the one from partzilla. Do you think I should give it a try? 

You need to upload photos to a third party host like Imgur and then link them here so we can see what you're asking.

Hello @Mark,

Here is the picture link:

imgur.com/a/needle-3dRngOF

This is a case where a picture is worth a million words!

There should be a sealing washer under the seat like in the top picture...  you can probably use the old one if not damaged...  Seat should have the same threads, don't force it if it doesn't... there is usually a size stamped in the seat that designates the size of the entrance hole to the seat...  numbers should be the same or close (0.8 comes to mind)

Other than that, the new needle is an updated rubber-tipped type that should seal better.  And of course you need to make sure the float level is set correctly...  basically float arms should be parallel to float bowl gasket surface...  adjust by bending tang that contacts needle in center of float

That makes sense. I noticed the overall length was like 2 mm longer on the newer style. My main concern was the different style causing issues.

One other question, how tight should I have the air screw/spring on the side of the carb?

Thanks Mark for all your help!

Turn air screw in until it seats lightly and then back it out 1.5 turns. 

No, I mean exactly what I said.