I was doing some gearing calculations and I'm wondering if I've made a mistake somewhere. I've got the primary gear set at 1.8220, 6th gear at 1.075, rear tire set at 180/55/17 and at 14,500 rpm that comes out to about 187mph. Now I know that these bikes aren't topping out at this speed. Am I wrong with my calculations or is the bike just geared too high? I've read a lot about you guys dropping down a tooth and maybe this is why. Thanks in advance
Brendon

 

Ah, theory is a wonderful thing, isn't it? A 600cc engine isn't powerful enough to overcome the resistance that the atmosphere puts on the bodywork, otherwise known as aerodynamics. I don't know what the max speed on these is, but I would guess that it's around 160mph.

 

On my 2002 Cbr f4i Ive gotten her to 160 and it was running about 12 thousand Rpm..Oh and its completly stock so maybe that will help.

 

157 is the top speed for the 06' F4i i think

 

Not sure if this helps but i got a 06 f4i stock and got it up to 161 according to the odo but not sure if that is correct. I Remember reading a while back that the odo were wrong by a certain amount of mph's.

I do highly doubt it could get 187 is that were most 800's top out at.

 

There are a couple of variables to that question. First you have to have a perfect road, with no wind. Second it depends on the rider. How much he weighs andhow tall he is. Third how much fuel you have, the more fuel the more weight, lessen the load the faster you can go. And finally what has been done to the bike? Is it stock, does it have a custom exhaust? Does it have a power commander? And last and finally, all speedometers are not 100% accurate. Mount a GPS on your bike and ride and see how fast you really aren't going. There is a slight deviation of your speed, so if you think your doing 160, chances are you are going a bit slower. But why does anyone need that much speed? Just cause you can do it!!!

 

Hi there. I've done EXACTLY the same math problem as you have in an excel spreadsheet. I too had problems calibrating it. Sprockets and gear ratios are nice easy numbers to work with - the biggest error I found was getting a tire diameter that is very percise. If it's not percise enough at high speed the little error becomes a big error. I tuned my tire diameter by using known speeds - which isn't ideal. I really want to ground truth my numbers over a long distance with a GPS.

If you want to play/correct my spreadsheet, PM me, and I will provide a link to it.

Cheers,
woot.

 

One more note - if you just use the tire size as it's listed on the sidewall, the circumference you calculate will be considerably off. I've tried that too... the first time I did my spreadsheet I used 1.9 something... my new value to work from is 1.831 meters (which isn't perfect EITHER!)

 

Like Litre1 said, aerodynamics and engine displacement become the barrier that can't be overcome. The gearing is a function of ratios and doesn't take into account the power required to reach that calculated top speed.

Furthermore, your speedometer can be, and probably is, up to 15% percent off. 160mph easily becomes 136mph. Which to me, is more believable.

 

thats interesting, I didn't know the stock bike could not reach its redline, so my question is for those of you running different gears, are you able to reach your redline?

also you guys that aresaying that gears don't matter are wrong, it doesn't matter if your engine is 5hp as long as its rpm and gear advantage allow it to multiply the torque to the wheels to be greater than that of the drag coefficient then it will continue to accelerate