I have a 89 Phazer with 12,600 mile on it. Yeah that's a bunch. Anyway I cleaned the carbs and put new oil and fuel lines on it. Runs real good… But it will only go about 50mph. Right out of the hole she'll do about 60 but then it just won't do more than 50. It takes off and runs good no bogging. I can back the throttle off to about half and it stays at 50. Is this a clutching issue? Oh, compression is 120 a side. Thanks for your help.