Quick Acceleration????

[jlavallee]

Everyone is pretty much right on their responses. You are simply changint your final drive ratio.

If stock you had say a 15 tooth front and 45 tooth rear it would be a 3:1 ratio or simply put, it would take 3 revolutions of the front sprocket at the output shaft to turn the rear sprocket (and thus, wheel) 1 revolution.

The powerband and engine will not change at all. ie. the bike will still make it's peak at the same rpm. What will happen is that if you drop teeth from the front or increase at the rear you will reach that rpm at a lower speed. The bike will feel much more powerful but you'll loose top end.

Some points to consider...

- Is there an rpm that the bike vibrates a lot at? You want top make sure on a street bike that you don't get into a buzz zone at your normal crusing speed.

- How far off is your speedo going to be? Let's say you have a current gearing of 16/43 for a 2.69 ratio and you go down one in front and up two in the back for a 15/45 ratio of 3 then you've got about 11.5% difference. That'll feel like more power but at an indicated 75 you'll be doing around 67mph.

- If you go too small on the countershaft sprocket then you can get rubbing on the chain and increased wear since the chain radius is decreased and you are distributing the same power through fewer teeth.

- Does your bike have a lot of driveline lash (jerks on and off throttle) now? This will be maginified with shorter gearing.

- Are you changing the chain? You are usually ok to drop one and maybe add one but it depends on how much adjustment you have.

This is a common change but those are some of the items to consider. If you're racing you want to set your gearing like andy said so you can get as close to ideal as possible. In a proper race bike with a cassette trans you can change all gearing to make sure you're in as close to perfect gear as possible all the time.

Without writing too much detail you can get an idea of the basics. The cheapest method is to just buy a -1 sprocket for the front and try it. You'll usually have enough adjustment and low cash outlay. If you still need more then buy the rear too or maybe just go up one in the rear for an in-between comprimise.

[weavefish]

+1 on the write up  thanks. was wanting to do -1+2 from a 16/43. dont care much for top end speed. i dont have a rough spot in my RPM and the throttle isnt really jerky so im not too worried about it. i might start off with just going -1 in the front with my stock chain....but then i saw http://www.motorcycletoystore.com/sport/shop.php/chains-sprockets/sprocket-kits/afam-stealth-520-chain-and-sprocket-kit-honda-cbr600rr-2003-2006-/p_2881.html and lookst to be a good thing if i convert to the 520

[jlavallee]

No problem. Like I said, I'd try just a countershaft sprocket first and with minimal outlay you'll at least know if you want more or not. If your chain/sprockets are due for replacement anyway at least you'll know what gearing you want as -1/+2 is a pretty big change.

If you decide that -1 is pretty good and you're changing the chain/sprockets anyway I'd recommend that you buy a kit that will leave the stock # of teeth on the front and go up in the rear. Especially if going to 520. That said, if you're not racing and the weight is no big deal I'd stay with a stock 525 or 530.

[weavefish]

well im gonna drop the front 1 tooth and see how i like it. if i still feel i want more ill do the -1+2 and put a 520 chain on. i dont need a new chain to do just the front right... dont know if i should change both or if i can do just one sprocket

[jlavallee]

Providing you still have a reasonable amount of adjustment (say 1/3 or so left) you can just change the front and nothing else. Seeing as how they offer a 15/45 kit I'll assume that a 15 will not cause swing arm rubbing.

[weavefish]

yea should be fine. gonna see how it feels. would be sweet if thats the only mod i need to get the desired feel from my bike lol only cost 40 bucks

[weavefish]

well just got my drive sprocket in today ( -1) putting it in right now cant wait to try it out.

[zipbyu]

You stated, "i don't care about top speed" thats because you have not reached it.  if you had, you would be, and wanted more out of gearing.  you are going in the right direction for the track you ride.  as stated every track is different and every riders exits speeds are too.    

[weavefish]

You stated, "i don't care about top speed" thats because you have not reached it.  if you had, you would be, and wanted more out of gearing.  you are going in the right direction for the track you ride.  as stated every track is different and every riders exits speeds are too.    

ha ha ha... ive been at top speed... wasnt all that. but ill see how i like it tomorrow

[Noleftturn]

Darn your hot ass house helping you do the sprocket...  LoL and I wasn't there that long.

[dmh2000]

I just changed to -1/+1 (15/43 instead of OEM 16/42) on my 2007 CBR600RR. I did it because at RFR there were some turns where I was in 2nd and the RPM's were too low (don't laugh, I'm slow and fat). I didn't like downshifting to 1st and risking a neutral. I haven't been to the track yet but on the street it is great because now I don't have to slip the clutch when starting in 1st. And it just bumped me up one gear at every speed. where I used to be in 4th now I'm in 5th etc.  It should drop my top end from 160 to 145 (as if that matters). The speedo is off 10% but that makes it easy to mentally adjust. if I show 77, I'm at 70, 44 is 40 and so on. I changed the chain too. the only thing is it sounds a lot different now so I am getting used to that. btw I went with a steel rear sprocket since for durability, even if it isn't as cool looking as a race sprocket.

[cnrcrvr]

I have a collection of 4 different sprockets for the front and rear of my bike and with all the different ratios I have tried I never had an issue with my Speedometer being off at all. Now my bike is a 92 GSXR 750 with a mechanical speedometer cable that reads off of the front wheel. Are the newer bikes using a digital speedometer that reads the speed differently?? I am just curious and trying to learn some new things.

Thanks, Mike

[MotoPutz]

I believe its a sensor in the lower end now that is electronic to a digital speedo.

[dmh2000]

yea, the speedo runs off the countershaft and doesn't care what the wheels are doing. What is missing is that it would be reasonably easy to make the digital gauge programmable so you could calibrate the speedo. I expect to see that in new bikes in the near future.

[weavefish]

Darn your hot ass house helping you do the sprocket...  LoL and I wasn't there that long.

does that make any sense? well thanks for showing up with out the tools i needed :p

yea, the speedo runs off the countershaft and doesn't care what the wheels are doing. What is missing is that it would be reasonably easy to make the digital gauge programmable so you could calibrate the speedo. I expect to see that in new bikes in the near future.

yea i hope its all i need to do. havent changed the chain yet.