The rpm's your engine normally reaches in the first 4 gears are not indicative of what you’ll reach in top gear. Power to weight times resistance accounts for a lot. Someone weighing 245 lbs. on a Harley weighing 800 lbs. powered by an engine with less than 90 rear wheel hp is lucky to go over 110-115 mph. My sons little Suzuki SVS 650 makes about the same hp (less torque) than my 09 S/G but combined weight rider and bike is more than 200 lbs. difference. Simply put he will leave me behind in any gear and keep pulling away until he reaches about 120-130; this while on a bike considered entry level by today’s standards.
My 2003 K1200 GT was rated 130 hp at the crank; most likely about 110 at the rear wheel. Redline on that motor was about 9,700, yet in 6th gear top speed was 147 at just a bit over 5K and it would not budge a lick over that because it had reached it’s max output given wind resistance to power output. The bike weighed 640 lbs. if I recall; almost 200 lbs. lighter than my 09 S/G.
If you can hit 115 on your Harley, don’t assume you’ve got a lot more just because you’re not at redline.
It’s perfectly achievable to expect 110 mph from most Harley’s today, but much more than that is usually wishful thinking. I can see where someone who weighs 245 lbs. on a relatively stock Harley with no more than 80 rear wheel hp could very well peek out at 105 mph. Your next option would be to dump about 3 thousand dollars into your engine and maybe have bragging rights to say you can reach 130 mph! But who cares, when anyone on a 1995 bone stock Honda 600 can still pass you like you’re standing still. If fast and top speed is the goal, you'll need a completely different motorcycle. If your Harley’s running great and it’ll take you to 105 mph, that’s all that counts.