Let me give you these figures first:

 

-The loop is 4 lanes wide.

-It's diameter is 60 feet.

-It's circumference is 188.4 feet.

-The rider is riding a 2000 CC motorcycle.

 

How fast would he have to go to get through the loop?

Through the loop is easy and you can do that at any sensible speed.

Round the loop is a bit more of a question.

Incidentally, shouldn't it be 188.5 feet?

No, because I calculated 188.4 feet.

 

What do you mean by any "sensible" speed?

If you try to ride a motorbike at a very low speed- like walking pace or lower, it is difficult to maintain balance (unless you have a side car).

And above about 100 MPH it's quite difficult to control.

Anywhere between those speeds would be sensible.

 

60*3.141592 =188.4955.....

Rather nearer to 188.5 than 188.4

Now you need to find out the difference between going through a loop and going round a loop.

Can you describe the 'loop' better, and what the bike is doing in/on/around it.

 

Is the loop like a circular running track on the ground? is it a wall-of-death type loop? is it a vertical loop? How wide is one lane, how heavy is the bike, why does it have such a huge engine?

I mean this kind of loop:

 

I found this rather useful site which deal with exactly the question you posed.

 

http://physics.info/centripetal/practice.shtml

 

My maths skills are pretty poor, but i reckon the bike will want to approach the loop at about 50Kph and be doing about 20Kph at the top of the loop.

Then if the bike was going 200 km/h, how long would it take to exit the loop?