I'm going to change the gearing on the 4Fi. I know there are many threads on this topic. I've read quite a few but I have a couple questions. 1) I know the top end will be affected by this new gearing but how much? What is the new top speed with this set up? 2) Also how is the mpg affected at highways speeds (80mph)?

 

Are you planning on going anywhere near the top speed? I didn't think so.......

You will probably see a few points off of stock mpg with a gearing change.

 

Only if I'm late for church!

 

My $0.02

-1/+2 is a pretty drastic change and I wouldn't recommend it unless you really want to wheelie alot or do track days on a tight track. In 6th gear the bike will do roughly 10 mph for every 1k rpm (60mph at 6k rpm, etc).

For the average street rider/commuter I'd recommend switching to 520 and run -1 front/stock rear sprocket. It'll make a big improvement in acceleration without winding the crap out of your bike all the time.

 

I have this combo in a 520, love it, Honda should have put em like that. Wheelie alot? I dont think so, this will make it easier to wheelie but not as drastic as rolandk stresses. You will loose about 10mph off the top end, rolandk is also off on the rpm's, but not by much. At 80mph you will running roughly 7Krpm in 6th gear. I can get 45mpg with mine, not this is w/o ******* it. Spirited runs I get about 35mpg, and this is on a F4 carbed bike. The EFI on A F4i should do a lil better. I say do it, you'll love and wish you did it long ago.

 

I have -1/+2 on my F4, heres what i got out of it. Before i geard it i had this bike up to around 150mph... i recently tried to keep up with some friends and i found i just about topped out at about 130mph. The whole reason i geared my bike was to stunt.(i actually am thinking of going further). This gear combo doenst restrict you at all in the city. sometimes i hate doin highway cuz your doin 75 and ur tach reads 7 grand... it does help acceleration alot... and i only lost about 8-10 mpg, now im down to around 38-40. In my opinion this gear set up is a nice mod to get a lil extra kick and still be able to ride highway. any more than this it gets hard. im thinkin of goin -2/+8, there goes highway riding...
my $.02

 

Ummm, no. I have a speedo healer gps calibrated to 60 mph.

 

I dont have a speedo healer but have calibrated with a gps and the nice speed signs LEOs set out and other vehicles. I know what I said is true, and I ride my bike 10k+ a year. And if I remember correctly the F4i's came out with even taller gearing than the F4 so a -1/+2 wouldnt be as low as it is on my F4.

Not doubting your findings, but like I said I know mine are acurate too.

 

Stay away from the 520 kits. The chain is not as strong as the 525. Those numbers indicate the width. The higher the number the wider and stronger the chain. You can verify this by going to any chain mfg.'s website and compare the same chains with different widths, note the tensile strength. If your just toolin round town back and forth from church and what not, then you'd want a stronger chain that will stretch less and last longer. Also try to find a steel rear sprocket, the aluminum ones will wear faster. If you plan on goin to the track then go with the 520 kit with aluminum sprocket. Thats IF you NEED the extra tenth of a second off your lap time.

 

Anyone can easily figure out their speedometer error/change.

When I had -1,+2 my error was around 11.4%

To figure out the change what you do is take the stock sprocket ratio compare it to the new sprocket ratio.

I use these graphs and several other spread sheets to help me pick gear ratios... on the local track there are only a few places where -1,+2 really helps and that's because you get between gears on specific corners.

On the highway 0,0 is good - keeps the rpms down. At 60mph you are at ~5500 RPM vs 5000 RPM

Here is 0,0


Here is -1+2