Gearing an F2
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Gearing an F2 - 4/23/2007 9:49:01 AM
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lee1rbc
Posts: 98
Joined: 3/22/2007
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This is a post on my .02 of gearing Your F2 and some things to think about before gearing.
The point of gearing is to increase the performance of the bike but for what. Top speed? 1/8th mile? 1/4 mile? Track bike?
One thing to remember is no matter what sprockets You put in, the spacing of the gears does NOT change. Only the mph of the gears change. So if I have an F2 that is geared to do 10k rpms at 100mph in 3rd, and an F2 that is geared to do 10k rpms at 100mph in 4th, both bikes will pull the same. In other words gearing does not increase H.P. Just changes the mph each gear produces its H.P.
Dropping one tooth in the front is going to bring the biggest gain. Remember when You add teeth to the rear it is a bigger sprocket, that adds more unsprung mass to Your rear tire. So You will gain excelleration by the gearing but You will loose a small amount of horsepower with a bigger rear sprocket about 1/2 h.p. Not alot but for some people that matters.
Hear are some specs on the gearing for an F2.
Primary Drive gearing 1.863
Sprocket drive 43/15 = 2.87
1.863x2.87= Total drive gearing 5.34:1
Gears....
1st 3.14
2nd 2.06
3rd 1.59
4th 1.37
5th 1.20
6th 1.09
Factory tire is 24" in diamiter.
43/15 = 2.87 x 1.863 Final gearing 5.34
42/14 = 3.00 x 1.863 Final gearing 5.59
43/14 = 3.07 x 1.863 Final gearing 5.71
45/14 = 3.21 x 1.863 Final gearing 5.98
Lets say You want to set the bike up for the 1/4. There are three main things You should look at. 1st gear (take off), how many shifts (fewer is better), and rpms at the finish line (peak H.P.at finish) .
example:
Your F2 does 117mph at the finish line in the 1/4 mile. With the stock gearing 3rd gear tops at 109mph and 4th gear tops out at 127mph. So I want to change the gearing so 4th gear tops out at a little over 117mph.
To do that the ideal gearing would be 5.71, that would put You at 118mph in 4th gear. If I go to a 5.98 setting 4th tops out at 113mph forcing me to shift to 5th just before the finish line.
Please if You have something to add please do, also I hope this helps.
Hear is a link I use to help calculate gearing and m.p.h.
http://www.wallaceracing.com/calcmph.php
_____________________________
1994 CBR F2 Stage 1 jet, Yosh exhaust, fiberglass body.
2006 ZX6R 636 green.
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RE: Gearing an F2 - 4/23/2007 12:04:16 PM
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bindelsf2
Posts: 1331
Joined: 5/7/2006
From: YES THAT IS A 900 ENGINE IN A F2 ON SPRAY
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Great Post!! now i have some ideas in mind!
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honda CBR 600F2/900RR
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RE: Gearing an F2 - 4/23/2007 12:24:55 PM
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jaghunter
Posts: 392
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Again, great post. Gives me alot of Ideas and ?Questions?
If you drop one in the front and don't change the rear, will there be a noticeable difference?
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RE: Gearing an F2 - 4/23/2007 12:34:53 PM
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Dan1220
Posts: 106
Joined: 10/13/2006
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yea, there will be a noticable difference I'd say
great post
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RE: Gearing an F2 - 4/23/2007 1:12:46 PM
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lee1rbc
Posts: 98
Joined: 3/22/2007
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If You gear one down in the front You will change Your overall gearing of first gear from 16.76 to 17.92. Think of it this way, in the stock setting 20 mph You are at 4,800rpms. Thats about 30rwhp. If You go down 1 on the front at 20 mph You will be at 5,200rpms thats about 33rwhp. So Your putting down more H.P. sooner.
_____________________________
1994 CBR F2 Stage 1 jet, Yosh exhaust, fiberglass body.
2006 ZX6R 636 green.
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RE: Gearing an F2 - 4/23/2007 3:10:47 PM
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jbreit
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Gearing, as you said is a trade off between top speed and torque. While measured HP at the ground/wheel is unaffected by gearing, torque is affected.
The weight of adding 2 or even 4 teeth to the rear sprocket is insignificant in regards to both suspension and HP. Besides, when most people gear up in the rear, they switch to aluminum. The theory is accurate, but the affects are imperceptible.
Smaller front sprockets are a source of increased friction and wear.....a smaller front sprocket puts a greater amount of tension in the chain, and also articulates it more...both increase wear.
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RE: Gearing an F2 - 4/23/2007 4:29:25 PM
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jaghunter
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Thanks for the info.
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RE: Gearing an F2 - 4/23/2007 8:21:52 PM
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lee1rbc
Posts: 98
Joined: 3/22/2007
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Nice reply, I think it does go to mention that gearing is not the end of all means, yes it does feel nice when 1st gear has more snap at the throttle, but a fast bike is one that is tuned well and has the best suspension and gearing set for its application.
_____________________________
1994 CBR F2 Stage 1 jet, Yosh exhaust, fiberglass body.
2006 ZX6R 636 green.
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RE: Gearing an F2 - 4/23/2007 10:26:47 PM
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bmg velocity
Posts: 1353
Joined: 12/14/2006
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Nice post...
A bigger sprocket on the rear will make it easier to wheelie...gives more "torque"...
But...I actually like the stock gearing except for 1st gear on my F2, which I believe to be way too short.
Once you hit 30 mph.....time to shift...mostly due to that legendary buzzyness that CBR's have at
certain rpm's, etc (Like the fairing fuse box lid on the riht...I have put foam around the edges...still
buzzes...only one screw they used to put that on there...which was dumb on Honda's part...
I would like 1st gear a bit longer...at least to where it could pull to 50...without having to rev the
crap out of it.
When I start doing track days...I may gear my bike a bit different for that....but for now..it's good.
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RE: Gearing an F2 - 4/30/2007 12:31:52 AM
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xbatmanx
Posts: 13
Joined: 4/30/2007
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where can you get a good deal on gear sets with a chain to gear the f2 for more speed? I was thinking 16/43? I would like the bike to be able to 140ish maybe a bit more. It is mostly stock with a yoshi pipe. Is that possible? Any help is greatly appreciated.
Sean
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RE: Gearing an F2 - 4/30/2007 10:47:12 PM
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edwardtn
Posts: 251
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Should be 140ish now...but there is more you can do. You can get a Vortex sprocket set with 520 conversion off ebay for prolly around $140...maybe less. But even so, you lose some top end with the sprocket...course it's not like your red-lining in 6th gear, but the only think that can overcome that resistance barrier at top speed is horses...whether you get them by trying to be at a higher RPM range with gearing, or try jetting, K&N, and a full exhaust to get a few more horses out of the engine...I dunno. I know my 94 has just a V&H slip-on, no jetting, stock gearing, and it will get 142-144 consistently...and I have heard of F2's in the 150's...and I have heard CLAIMS of F2's in the 160's.
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RE: Gearing an F2 - 5/1/2007 8:05:33 AM
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lee1rbc
Posts: 98
Joined: 3/22/2007
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Here is a link that I like to mess with. It calculates the rear wheel H.P. needed to achieve a set M.P.H.
Honda CBR F2
Coefficient of Drag (Cd):.600
Frontal area (sq. ft.):5.98
wet weight of bike 440lbs + rider
http://www.rbracing-rsr.com/aerohpcalc.html
F2 produces peak h.p.(around 84) from 10,500rpms to 11,000rpms, so to achieve the best top speed You want to be at 11,000rpms at top end.
< Message edited by lee1rbc -- 5/1/2007 8:07:29 AM >
_____________________________
1994 CBR F2 Stage 1 jet, Yosh exhaust, fiberglass body.
2006 ZX6R 636 green.
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