Lew, what other mods are you doing to your to your engine, cause changing the final drive ratio alone won't get you there. I've done all of the mods short of the Freak, but my bike will only hit about 115 (btw, removing the emissions stuff only reduces your overall weight by about 0.2 kilos, but does absolutely nothing for acceleration or top end, since it is post combustion) You say you wouldn't even consider the 18t option, but the Speedmaster gearing is going the wrong direction for improving top end, since the 16t is really better suited for acceleration. Assuming 6500 RPM in 4th Gear, you only see 84mph with a 16t Speedmaster gear, 89 with the 17t America, and 95 with my 18t. Modify your engine to be able to get the horsepower needed will get you that top speed you desire. Unless you start doing some serious mods, your engine will need to be hitting 7400 to reach 115, and 8000 RPM to reach 125. It seems to me you need something close to 18t to get to 125, since that simple change from 16 to 18t lowers your engine speed to 7100 RPM (assuming you've got enough HP at that end of the powerband to get you to 125mph) So, unless I'm just a sod, you've got to go toward 18t AND modify your carbs/intake to get you the extra HP to beef up the upper end of the powerband, whether you're riding that crotch-rocket Speedmaster or our old tired Americas....
