Yes you can but you can get better performance out of just a primary spring then with a whole clutch kit. The clutch kit is designed to match the power output of the pipe. If you just use a clutch kit it can shift out way before the powerband of the stock pipe or not shift out enough. You need the power of the pipe to offset the different heavier clutchweights. If you dont have the power to spin the primary enough you will lose power either in the bottom or top end. A stock setup can perform alot better with just the spring.

 

Hey trailblazermudrunner,
You can install whatever you want. But you will see better performance with just a pipe vers. just a clutch kit. With just the clutch kit you might even lose some power because the pipe and clutch are not working in the same powerband. If you just want a clutch kit to see for yourself then I would just get a white spring to try first. Save you some cash. If you know someone who has a scrambler 400 with a clutch mod. get there stock spring off them and try it. This will be a white spring. Then you can get a new pipe later and you can still use the white spring with the new pipe.