My goal is faster accel without hurting top speed and mpg. What could I expect from a stock front and +2 rear sprocket with a 520 chain? What could I expect to gain from this? Also would this be the right set up for my goals? How about just +1 in rear and stock front? Is this a mod worth doing or should I just keep stock size? I was thinking Vortex sprockets with DID chain, is this a good choice in brands? Any advice would be very much appreciated! Thanks

 

Any faster acceleration achieved through adjusting your final drive ratio will theoretically always hurt your top speed. The typical quick accel kits are -1 +2. Using a lighter 520 chain and lighter sprockets, see: aluminum, will reduce the unsprung weight and the rotational mass and will help increase acceleration marginally but will not affect top speed so thats one way to go. But as soon as you start changing your final drive ratio you have to sacrifice in one area to gain in another. The -1 +2 kits just find a good compromise that increase acceleration without drastically hurting your top speed so just going +2 in the rear will help your acceleration a little and hurt your top end a little less than a -1 +2. Gas mileage usually increases 1-2 mpg too as well from what ive heard.

 

I also personally agree with the posts above. I personally would choose the faster acceleration over top speed, since it will feel a lot faster and you will use it more. Ask yourself how often do you ever go close to the top speed of the bike?

 

Take into consideration you're rpms will be higher while crusing on the highway. So you're not only losing top speed as well as losing mpg and the ability to cruise at a lower rpm.

Gas mileage only seems to increase because your odometer will off and will be reading a higher miles per tank than your actually getting.

To each their own, but i'd only lower my sprocket ratio if i had a track bike or stunt bike.

 

This would be true for highway cruising in 6th gear. Anything else you can pop it into the next gear and your gas mileage will not decrease and may even improve. I usually dont go higher than 3rd or 4th gear for everyday riding in residential areas. So the type of riding you mostly do is also a factor. Plus if he goes with the 520 chain and aluminum sprocket the weight and mass reduction will also help his gas mileage.

 

Thanks for all the replys. What if I did 520chain with +1 in the rear? Would that even be worth doing? How bad would that hurt top speed and how much would it raise my rpms? Or should I stick with stock gearing? Im going to buy new sprockets and chain for sure so thats why im asking just want to know if I could gain by changing. Sorry for all the questions im totally new to this been a car guy and now im in love with bikes so im trying to learn. Would my speedo be off with +1 in the rear? Lastly Why does the 600rr cbr have 2 less teeth in the rear then the f4i but is faster? or atleast thats what I read.

 

A +1 in the rear probably would probably have little effect. I believe the stock fdr for the f4i is 2.88 (16/46 stock sprockets) so going +1 in the rear would make it 2.94 which would help your acceleration a little and probably only hurt your top end by a couple mph but no I dont think its worth it. +2 would raise your fdr to 3.00 and youd probably see top speed decrease of 5-7mph. Youd probably be the happiest with that and a 520 chain and aluminum sprocket if you dont mind the shorter longevity of them compared to the 525 and steel sprocket.

As for the 600rr's all I know is they have 3 less teeth (16/43) but they could have a different transmission with shorter gearing. So maybe that with a lighter drive system and lighter curb weight and probably a couple extra hp would explain why their faster. Dont forget rr stands for race replica so theres a little more that goes into those bikes than our f4i's

 

Thanks for the fast reply and the great info! That makes more sense kinda like a rear end on a car, the lower the gear for example a 4.10, the fast off the line but less top end. So I think ill go with +2 in the rear. My last couple of questions lol How far off would my speedo be and If its bad then how can I correct it? Also you said the 520 with aluminum sprockets wear faster, How much faster are we talking? Like ill have to change them every season? and Lastly would this set up make wheelies easier lol jw? Thanks again for helping I really appreciate it!

 

yeah exactly just think of it like a rearend in a car. Stock speedo is off like 5-10% i think but i couldnt say how much this would effect it. You can buy a speedohealer to fix it but theyre like $100, thatd be your best bet if you didnt mind the price. Im still using the stock gearing but I think the aluminum sprockets do need to be changed every season or every other season depending on use and abuse. Yeah it should make wheeliers easier since it will give you a little more "torque" in a way. Obviously the engine wont be making more but you get what im saying. Thats why you see stunt bikes with huge 50-60 something tooth sprockets that are the size of the wheel.