[Dr Mayhem]

Look for "Royal Enfield" then "Interceptor"

https://www.gearingcommander.com/

(Edited August 8, 2020 to update link)

[Dr Mayhem]

I added 1" to the rear tire O.D. and 2 teeth to the trans sprocket, it slowed the motor down 854 rpm at 85mph in 6th @4799 rpm. Only 200 rpm off torque peak

These come with 6spd folks so row it like you own it huge step up over a 5spd and you can't even compare it to an antiquated 4spd

[Dr Mayhem]

These bikes are geared for a theoretical top speed of 105 MPH

Based on 44 HP @6840 rpm, someone onboard my weight 165lb, with two teeth up (17) on the trans sprocket and under ideal conditions 115 should be attainable 

Mileage falls off considerably cruising past the motor's torque peak of 5100 if you want fast commutes

My wife's 2010 Toyota Yaris with it's larger o.d. tires (about 1"),  1.5, 95hp motor will indicate 110, so in actuality probably a bit more,    also more aerodynamic than they look I guess

[Enfield Pro]

I added 1" to the rear tire O.D. and 2 teeth to the trans sprocket

I may be confused but doesn't increasing the sprocket size on both the front and rear cancel each other out? To gain top speed I always thought up in the front down in the back.

[Dr Mayhem]

I may be confused but doesn't increasing the sprocket size on both the front and rear cancel each other out? To gain top speed I always thought up in the front down in the back.

You are correct, but a taller rear tire gives the same result as a smaller rear sprocket. In the case of a 130/80-18 vs a 130/70-18 it's an inch and results in 3.909% higher overall gearing. Specifically talking about a Conti roadattack radial here. Tire also raises the rear 1/2 inch for bit sharper steering. Steering a little slow on these bikes I think, at least compared to my Buell. Probably the stock tires contribute a lot also. win-win going to this taller tire on a GT I think