I second that. I assume you are hitting this with an IR gun while the bike is idling? If so fatten the mix up a little on the hot cylinder, it should cool slightly.
He's gone to the trouble of very clearly going through the process in perfect detail so I won't screw it up with my version. Check this thread from Dannymax if you're having trouble syncing carbs.
https://www.vmaxforum.net/threads/carb-sync-procedure-for-carbtune.43398/
Shadetree has a great channel. I remember that bike making some awesome sounds when I first watched that video.
Check out his vids starring the Kawi H2 powered chopper his friend built. That thing is another ripper!
My Hindle 4-2-1 has the same problem on the rear cylinders. The headers are about an 1/8" or a 1/16" from the plastic battery box. If I let it warm up too long it melts the box near the header pipe.
I am on my third E-bay battery box. (thanks Pinwall Cycle!)
Yo, Fire-medic! It's been a long while. Hope you are doing well in these crazy times.
It is exactly like a choke rod bushing in shape and material, only about three times their size.
https://www.instagram.com/p/B_F0AocATck/?igshid=1h1visf6e5my8
Clif's notes- bike has been apart for far longer than I intended. Just got around to fully rebuilding each carb and racking them up. I have no extra parts, except this. It is made of nylon or some sort of stiff but slightly flexible plastic type material...
I have one in my backpack, and they can be changed without tools if required.
Less weight (although a minor concern...which is why after 20 minutes of cursing the two front coils are still where the factory installed them!)