Need help. I have two 2003 rangers, one is a 425cc 2x4 and the other is a 500cc 4x4 (UTV) with a governor. The 500 has zero top end and the only difference that I can find is a solenoid for a vacuum line that runs to the carb. Disconnecting the solenoid gives me more top end, but it runs really rough, any ideas? The UTV is considered a "farm vehicle" and is limited to 25 mph, can I change the carb to the same one that is on the 425cc?