Royal Enfield Interceptor/Continental 650 belt drive

This kit has been designed to fit without interference on the stock 130/70/18 and 150/70/17 tyres.
It has also been used with the higher “16T mod” gearing with a taller 140/70/18 rear tyre.
One Rider is running a much taller 130/80/18 with standard gearing, but had to remove the centre stand

Gearing is a bit confusing with a larger number being "lower" geared – IE the -Inter / Conti stock sprocket ratio at 2.53:1 is lower than the "16T front sprocket mod" at 2.375:1

 A lower gear ratio (2.53) will accelerate  quicker, but top speed will be lower.  At highway speeds the engine will be spinning at a higher speed, and depending how fast you are riding, you may not want to work the engine that hard for very long.   

 A higher gear ratio (2.375) will accelerate slower, but (theoretical) top speed will be higher IF you have the HP to pull the gearing.  Top speed on these bikes is usually not a consideration, however and some riders, myself included, would prefer lower engine speed on the highway.  When higher geared, cruising speed rpm will be lower, and in the meat of the TQ band.   

Carrol Shelby famously said “horsepower sells cars, and torque wins races”.  RE Street riding is mainly in the engine torque band, I try to match gearing to my riding style.  Having a cruising rpm in 6^th in the meat of the torque band, and not flogging the engine to death, works best for me. 

 The Enfield 650 engine has modest torque and horsepower, so gearing becomes a compromise between acceptable performance, the ability to pull a higher gear, with ones tolerance for wringing its neck to keep up with motorway speeds in some countries.  

So how does this math translate into seat of the pants riding:

SPEED IN KPH(MPH)       RPM Stock gearing          RPM "16T mod" higher gearing

100   (62)                         4140                                3890

110  (68)                          4560                                4280

120  (74.5)                       4890                                4670

124  (77)                          5150 TQ peak

130   (81)                          5400                               5050

132   (82)                                                                 5150 TQ peak

140   (87)                          5910                               5450

RPM is calculated and does not account for the bike weight, rider weight, rolling resistance, or drag from panniers and a windscreen - measured rpm will be higher than this calculated engine speed. 

You have a choice of gearing when buying a belt drive, so give it some thought………………….Most riders prefer the higher ratio, as little sacrifice in acceleration, with the benefit of lower engine speed.  


BELT TENSION TOOL:

A belt tension tool is highly recommended.  Proper tension on the belt is important for belt performance and life.  You will need a belt tension tool, to apply 10lbs of load to the belt in order to properly adjust the belt, similar to how you would adjust the chain.  A simple generic tool, and I have been using the Harley once since the late 80's - also manufactured by OTC, Motion Pro and a host of generic manufacturers.  A generic one is listed under options should you not have one