I use B Dasher + Mushroom Wheels for some time trials, and B Dasher + Red Monster Wheels for Neo Bowser/Koopa City. The Barrel Train is also pretty good.
There's an edit button located at the bottom right of a post you make. If you want to add more to what you're saying, then it's better to edit then make another reply before another member does.
As for answering to the topic....
I don't really know.
The Soda Jet seems pretty good. It works well with Mushrooms / Sponges depending on what character you're using. And as the ones Nin mentioned above. The Blue Seven seems pretty averaged as well with the Zuccini and the Gold Kart.
Edit:
I mainly stick with the Standard Kart, Standard Wheels, and Swooper glider. Figuring that I somehow do well with them more than any other kart combinations I've chosen.
I love the Bumble Bee Kart (I forget the exact name...it's become so automatic "A" pressing) with the wooden wheels, using Lakitu. It gives nice speed, GREAT handling, plenty of acceleration, and offroad goodness
You can use yoshian's combo but it's really hard to obtain all those parts. or use B Dasher + gold wheels + paraglider or Zucchini + roller wheels + flower glider