What causes your bike to lose top speed overtime? My bike is past the 60k mark and when it comes to topping it out. Its starting to fall short and can't get passed 145mph (give or take) I could keep the throttle pinned and it won't even climb after that. Before I could get it well above and maxxed out.

 

Dirty air filter, dirty spark plugs, bad fuel pressure regulator, dirty throttle bodies, out of spec valves, poor flowing/clogged injectors, low compression, wheel bearings going bad, brake pads dragging..... there are a million things that can cause you to loose that last 20mph which means it's hitting a horsepower wall. Either your not making the same HP as before or something is causing the bike to need more HP to get to the same speed/rpm.