Re: thumb throttle idea..here is how i did it...
I did that too, but found that it affects the throttle cable on the carb. Due to the linkage moving while the throttle cable doesn't.
So, I mounted mine under the dash on the rail at the edge of the plastic dash near the steering and ignition switch. From there I put it directly to the accelerator pedal. It is attached to the nut and bolt that acts as a stop, at the top of the pedal.
This way it pulls the throttle on using the accelorator cable.
You need a bit of slack Jimzuk or it alters the idle enough to really annoy.