There is some kind of interference at the throttle tube or right-side switch housing, or both. I completely disassembled the throttle mechanism, cables, and removed the spring from the carbs.
The "pull" cable was shot, and there is/was noticable resistance in the cable even when completely free of the bike. It was replaced with new. Next, the throttle/carb opening mechanism at the carb bank rotates freely. The "push" cable was free of any resistance, so I reused it. The switch housing and throttle tube rotates freely around the bar without cable hooked up, but snug down as if properly mounted. So far so good, and I was ruling everything out; one-at-a-time.
Here is what I believe is causing the problem: 1 - The throttle return spring is quite heavy. I wonder if someone has put an unusually heavy spring on the carb bank at some point within the past 32 years. I will be going to my local ACE Hardware tomorrow to find a lesser but similar return spring I can use. 2 - Once the throttle cables are secured back at the housing/tube juncture, and secured to the bar, there is very, very noticable drag at the throttle tube once the cables are tensioned. There is no housing-to-tube interference, but the bar underneath is corroded (but greased). I belive that the combination of an unusually heave return spring plus drag between the throttle tube and bar are causing my problems. I have a new chrome set of superbike bars to install, and with a lesser return spring I hope to have this problems solved!
My bike (pictured above) is a fantastic machine, especially for what I paid vs. a KZ900/1000 or CB750, and it would be a shame to sell it for this small, seemingly easy fix. I'll post more results tomorrow.
Trent
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