Hey "Throttle On", I won't tell you what gear to run either. How's that?
What I will tell you though and show you, so you believe and can confirm yourself. The speedometer is driven off the front wheel. That's a fact. Not the engine as you believe. So that part is confirmed for you.. Its powered through the other cable/Wire right next to your front disc brake hose. Held down under the 2 screws and hold down on your yellow left fork guard. The wire is zip tied and has a plug on it that runs right between the front brakes caliper and lower fork legs caliper mount. Directly into the attached hall effect sensor below the "Brembo" front caliper it points right at the disc rotor. There is a small approx. 3/8" diameter magnet embedded in the front disc rotor. As you can see pictured.
It senses rolling movement as soon as the bike moves about 1 rotation of the tire, or less in many cases. The speedometer powers up, lights up too. That triggers the hall effect sensor. The stock 13/50 gearing is listed to carry the bike to 112mph. It will. I'm running a 48 tooth in the rear. It will go close to 115mph. I've had it well over 100 mph many times and its spinning the back wheel doing this on compacted gravel or dirt roads.
I rode it over 90mph down the same Border access road with a completely flat GT 216AA front with the Tubliss still fully inflated, only with a puncture in the front tire that was 3/8" long from a mesquite branch. Right next to one of the center knobs. This was on the same day I described above when my Buddy was riding my G450X and he passed me twice in that sand wash. I have 2 U.S. Federal Agents who were witnesses to this. Both riding that day with me. I had a dyna plug kit in my pack and a CO 2 inflator. The CO 2 air charge in the tire itself that I topped the tire off before we came out of that wash was leaked out and away through the hole in the tire before I got out of the same sand wash and up on the road as I mentioned above. I didn't bother trying to plug the tire as it was leaking and spewing tire slime and I was only about 15 miles from home.
I removed that same punctured front tire when I got home which was by then throwing off and cracking the side knobs and installed a new one just like it. GT 216AA Fatty 90/100/21"
With a flat front tire it wouldn't pick up any more speed than about 90mph on the gravel AB compacted Border Access roads with that flat front tire and it was still fully controllable with the Tubliss system and a flat.
Look at your speedometer when you are on the dirt. If you can get it to hook at 160 lbs. I weigh 240 geared up. I can make it hook pretty much when I need it too. I don't have to worry to much about making it get traction when I plant my ass on the seat. The bikes got more in it then you think.
I've been riding big bore open class dirt bikes since about 1975. The only odd ball I've had that didn't have the speedo drive on the front wheel, was the speedo drive on my G450X. It runs off the rear wheel and the hall affect trigger is the magnet itself and counts all six bolt heads on the disc rotor, to get a speedometer reading. That set up doesn't make much sense on a dirt bike that has the rear wheel spinning most of the time. Its only accurate when its coasting or off the throttle.
On that bike, Well its not too accurate if you "Throttle On".
