That might sound like those endless advertisements which promising 10% more horsepower for a race air filter- or some shiny extra strong glowing hyper-kryptonite-supersphereo-graphical spark plugs, and you’ll get more for a extra fee. Nope, this one is totally legit and easy to do yourselves. Well yea, technically it won’t be a more power making motorcycle, but let’s look into the slight sketchy background first.
Motorcycle Sprocket Job
All those motorcycle manufactures are selling their models mainly based on two numbers… horsepower and top speed. Yea, that’s how they get you, just admit it. While the horsepower is one thing- they are achieving those high top speed numbers mainly via primary ratio, gear box ratios and secondary ratios. Of course also the wheel sizes have and influence as well as the general weight and aerodynamics of your bike. That’s something you kinda have to live with if you don’t want this to be your financial grave.
graphic credit: www.motorcyclespecs.co.za
Let me just give a small overview what kind of weight this has for race teams. Racing is all about acceleration and only a fraction of time about top speed. We could set up every single gear in the transmission to match corner speed and RPM’s in a perfect torque range for turn exit performance. A “longer” (more top speed) 6th gear could gain passing chance coming out of a slipstream before late braking.
The ratio was calculated on the mile exact to be fully rev’d out in 6th gear about one second before braking. Wind direction or a strategical aspect depending on- if you probably lead the race or if dog fights were predicted. All of this is a crucial part of racing. For you, we are looking at the secondary- also called the final drive. This is literally ‘outside’ the bike and can be done with regular tools and affordable parts. The influence can be surprisingly good.
So here is your scenario as the street rider or even track rider. The Germans have the Autobahn, giving their riders some top speeds we Americans on our Freeways won’t get to see ever. That might doesn’t include idiots here, but generally you are doing 70-80 miles per hour max, while your baby could do about 200 actually. That’s wasted energy if you ask me, sitting there literally never used. Another effect is, that the 1st gear is so damn long that you could do 70 with it already. The ratio makes this gear almost useless. So if we would change the final drive, it’ll also have a positive influence over the entire primary ratio for more ride-ability. Cool huh?!
The terms here are ‘longer’, for more top speed- and ‘shorter’ for more acceleration, and that’s what we want. The useful torque range will move by giving up on top speed. My Panigale 1199 is topping out at a 165. She doesn’t make 200 anymore, but the acceleration beats down the brand new V4, no kidding! So here is what I do, and that’s actually a good start out point for you as well…
I chose a specific ratio because this way, my ‘Cleopatra’ can still cruise at a 6800 rpm’s in 6th on the Freeway- while this ratio is still fair enough for the most race tracks I am going to to teach track riders. So no swapping drama here for me then. The general rule is:
Front:
- A smaller c-sprocket = shorter (more acceleration)
- A bigger c-sprocket = longer (more top speed)
Rear goes the opposite way:
- A bigger sprocket = shorter (more acceleration)
- A smaller sprocket = longer (more top speed)
Generally, I swap the sprockets this way: One tooth LESS on the front sprocket- and one tooth MORE on the rear sprocket. Rule of thumb is- one tooth more or less on the front sprocket is just like two and a half teeth on the rear. That is huge in terms of acceleration, drive-ability and responsiveness and you have no idea what you’ve been missing out here. So bare with me and get to it.
Go count front and rear sprocket teethes of your bike. Let’s say you have a 16 on the front- you go get a 15 for about $40. Now let’s say you count 45 teeth on the rear- you go get a 46 for about 80-100 bux. That small investment is the biggest ‘power upgrade’ you’ll ever get. Also no need to swap chain, because 1 down front/1 up rear needs the same chain length you already have. Unless you also want to convert from your huge OEM chain to a 520 chain kit (I covered that in ‘Coach’s Motorcycle Bible‘)
Most of the needed parts are easy to get to on eBay. They also have chains if needed. if you want to go a slight different route with your sprocket choice, I’d suggest to see the ratio/speed differences ones you know the numbers of teeth your bike originally has. Then compare it with the numbers you plan to go with here. If you are not sure about something- just drop a comment and I’ll see if I can help.
Please note though… if you make any changes in this regard- make sure all bolts are tight and take it easy riding it. Give it time to re-feel the new character of your bike. I’m not responsible for you bullshitting around, you hear me?! :-)
Headcoach Can Akkaya, Superbike-Coach Corp
