Until someone with actual knowledge responds, I'm happy to play the guessing game.

If it were duller, I'd think it was a bend of radiator hose. But given how shiny it is, I'll go with the some variation of the Home Depot option below (also available in chrome, white, brass or oil-rubbed bronze).

https://www.homedepot.com/p/2-in-ABS-DWV-Return-Bend-C5879HD2/100345955

Look at the post, Inlet Manifold, started by Zipdachimp, 10 posts below yours . Note my directions to -tuneing your intake - started by me on 6/30 16 @ 18:51
You can find it by going back to the first page of this section, looking to the upper left side of the page you'll see the page numbers,123...907 (currently)     click on one of the periods between the page numbers and a new page will pop up with all the numbers between 1 and 907, click on page 77(currently) and scroll down finding the post by using batman or the date and time. read and learn like I did . the length of the pipe you use is important , as it will improve(EV) hp at certain rpms (tunable by length) and is present at those rpms,  in any gear. when using the charts ,dividing the rpm by 66.7 will give you approx. speeds(stock gearing). I used 2" schedule 40 pipe as it is both strong and has nearly the same inside diameter as the stock CV carb.

That's true. you can however place  an elbow on the intake on that bike an run the filter behind the battery box where it is protected. I ,myself gutted and altered the stock air box ,ran the intake inside and moved two" Öldfellers " custom filters to the outside , one built in the door behind the right side cover,and one in the rear between the frame rails just in front off the rear fender. This allows you to still run the breather tube to the air box and the intake to be weather protected.  The bike appears to be to be stock.

ABS is more ridged  than PVC and tends to deform in sun light. Neither of these things endears me to it's use on my motorcycle.

This may work for you. It's the same diameter (2.25 in.) as the carb outlet. I purchased the 45 degree one.  I am hoping to install it this weekend using a K&N cone filter.


https://www.amazon.com/gp/product/B01CZTGTIK/ref=oh_aui_detailpage_o02_s00?ie...

Not sure why we have differences.  Looking the the carb with calipers.... OD is 57mm (don't know if it is stock or not).  Airbox - OD is 62mm.  The pipe I listed above - OD is 57mm.  I know the ID's are a bit difference because the pipe is a thin wall... but certainly not 17mm.

What am I doing wrong?

I read an older thread on intake size...etc.  Me, I'm just looking at increasing the air by using the cone.  I'll increase the exhaust by trimming down the port.  Then I'll get the carb rejetted.

What am I missing?

I was strictly looking at it from a rubber (2.25 in. hose) connection point...pipe to carb using external dimensions. And, yes I am going with the cone for looks.  For me, I don't need a high performance bike.  Thanks for the correction on the 40mm.  For me, there's a lot to learn on this site.