The needle jet is a snug slip fit and the main jet holds it in place. No you don't need to change it unless it is worn. The needle and needle jet are a matched set, so if you replace one it should be with the same part.
The Canadian bikes came with an adjustable needle that you can use but it's best to use the Canadian needle jet to go with it.
On changing the air intake or exhaust you might need to rejet to match. Testing is the only way to do it right. You make a change and test, make a change, test. Don't make two changes and test, you won't know which change made the difference.
The carb guide explains this.
Leo
The Canadian bikes came with an adjustable needle that you can use but it's best to use the Canadian needle jet to go with it.
On changing the air intake or exhaust you might need to rejet to match. Testing is the only way to do it right. You make a change and test, make a change, test. Don't make two changes and test, you won't know which change made the difference.
The carb guide explains this.
Leo