Im new to the forum and new to street riding (most of my power-sport experience is w/ATVs). I use my 99 CBR 600 F4 as a commuter bike, about 90 miles a day. I know I cant have my cake and eat it too, but I want to have a bit more acceleration and maybe get the front end up every now and then. But since I travel so much I dont want to lose too much in the MPG department. My sprockets are due for replacement. I was thinking of dropping 1 tooth in the front sprocket and adding 2 to the rear. I noticed that a lot of people have done this, but my question is how much MPG do you lose with this change? My normal speed is about 75 MPH. Would I still see a noticeable difference if I just did the 15 T in the front? Also I was thinking of dropping to a 520 chain. Any thoughts?

 

If you do a lot of highway riding at 75 I wouldn't go any more than -1 on the front, and leave the back. I did that on my F4 and it really makes the bike a lot more fun to ride and it seems perfect to me. It did raise the RPM's though so I wouldn't suggest going to crazy on gearing it down for highway riding. With enough work I can get the front wheel up in 3rd at highway speeds with that gearing, so I would just get used to the bike, it will wheelie easy enough once you get used to it.

 

Thanks for the input. I think that is probably what I will end up doing. solomotoParts.com has a 520 chain/sprocket kit for $150 w/free shipping. Has anyone found a better deal?

 

I think I paid $160 for the kit in my signature because I upgraded to black sprockets and a gold chain so that price is right in line. Trust me, you won't be disappointed with the -1 in front.

 

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I just got a 520 conversion for my bike, i haven't had a chance to ride it since i had it installed still have snow here. i went -1 in front and up 3 in back. I don't do a lot of highway driving though. I'm in town and stunt. I paid like $130 from two brothers, not including install. i had them make me a kit and all i have to say is make sure the sprockets are steel and not aluminum. you will have to keep an eye on the aluminum sprockets for wear, and from what i've been told, replace them faster. have you installed a better air filter. K&n makes a great filter for like $40. better gas mileage... Good luck and safe riding.

 

Thanks everyone. I ended up getting -1 in the front and +1 in the back (the back I originally intended to have stock but I messed up when I ordered). I did the 520 conversion. The bike definitely feels more responsive in all gears. I dont see much difference in MPG, but then again I havent compensated for the speedometer or odometer. Next on my shopping list is the speedohealer. Only downside I see is that cruising at hwy speed (80 mph)keeps me running at about 7k rpm. If I had designed this bike I would have made 6th gear much higher - just a cruising gear, and kept the other gears low for acceleration.
Thx again everyone!