Try this. Maybe I can confuse some one.
On the left side of your bike(Grizz) behind the big side cover is a group of wires with connectors (plugs if you will). In that group of plugs there will be a green wire with a white tracer. Just splice into the green wire with the white tracer, (leave it pulgged in) but add a wire to it. Go down 3 or 4 inches from the plug , skin the wire back and solider a piece of wire to it. Take this new wire to ground, just ground it to the motor, or frame.
You can now go as fast as you want in reverse.
If you unplug this wire and ground it, your reverse light will always be on.
And I'm thinking, It's been a while but If you do what I said it WILL override the reverse limiter, but your reverse lite will not work anymore. So the next thing I did was to put a switch to interrupt that new wire I just added going to ground. So now my reverse lite works. And If I want to over ride the reverse limiter for a bit, I just flip the switch.
You can just ground that Green wire with a jumper to see if it'll work.