Can someone tell me what this boss welded into the frame is used for?

Hey guys, I recently purchased a ‘87 ZX750 and I need some help locating 2 things. I’m new to motorcycle mechanics so forgive me. First of all I am going to change the front sprocket, and I know where it’s located I just need to know how to get to it. Don’t want to accidentally unbolt or unscrew...

Went for a ride and bike was pulling hard... then it seems to stumble a bit ... I would say at higher speed on highway ( 80 - 95 mph) Seems to come and go. However, when I got home I could smell gas. Took the tank off, looked at the carbs... no leaks , nothing ... :unsure: I think it is...

Okay. What's the trick to removing those closed plastic loops on each side of the fender that holds cables and hoses in place. I tried putting soapy water on it to try and remove it but no dice. Any secrets to removing them? I just need to remove the front fender.

From what I've read the 3rd crankshaft bearing starves due to: Low oil level Long wheelies Oil pooling in the head Early design ball type oil pressure valve Any thoughts on lighter or heavier than 10w30?