Larger front sprocket or Smaller rear ???

Hi all, Firstly awesome site.
Had my 99 VFR800FI about 3 weeks now & done about 1800kms so far & love it but im not into sports riding or racing off the lights. Im out to cruise the highways & not in any rush.
I love the sound of the bike & is the main reason i bought it but im wantin to drop the revs a bit & gain a bit more fuel mileage.
I was thinking about going up in size with the front sprocket by one tooth.
What i want to know is:
1. Will this be enough to drop the revs a bit more?
2. How far will this throw the speedo out?
3. If i go up 1 tooth in front & down 3 in the rear will this compensate & keep the speedo right?
4. By goin up only 1 tooth in front will this require longer chain?
5. If go up 1 in front & down 3 in rear will this keep chain at same length?

Sorry about all the questions but thought best to get them all out now rather than draw it out & keep asking.
All help is greatly appreciated.

Dan

 

You're thinking about doing what I already tried. I went up one tooth on the countershaft sprocket, and you can have the sprocket if you want to pay shipping. I was happy with it at highway speeds, but everywhere else not so much. Especially starting out from a dead stop, and worse with two people on board. The acceleration is not so good with the higher gearing, and you find yourself having to downshift at least one or two gears when going for a spirited pass on the highway. I didn't keep it on there long enough to get a very accurate reading on gas mileage, but it didn't seem to have varied much from the stock gearing. In fact I'm leaning toward going to a larger rear sprocket to improve low speed acceleration a tad. It dropped the revs about 300 rpm's at 70 mph if I remember correctly.

It makes the speedometer almost exactly on the speed, but throws the odometer off by about 7-8%.

If you go up 1 in front and down three in back, you probably won't be able to pull away from a stop. :smile: Seriously, that will do horrible things to your acceleration and probably make your top two gears unnecessary at any realistic speeds.

Going up 1 tooth in front will not require a longer chain.

Like I said, I have the one tooth larger countershaft sprocket and you can have it for shipping costs if you're interested.

Howard

 

Thats not possible. But otherwise good advice.

#3 The speedo is driven off the output shaft RPM, any gearing ratio changes you make will affect the speedo... and it sucks, trust me.

#5 2 teeth equals one link.

My VFR gets 48+ MPG backroad touring. Ruining your acceleration with a larger front sprocket probably wont net you any returns in mileage. Consider what happens when someone (I wont say who) put larger tires on his truck. The gearing said more MPG but the engine said "screw you buddy, your gonna spend a grand plus getting the gearing right or I'm gonna dock you 5mpg". If you make it harder for the engine to turn the wheel you will have to use more gas.

Just because your bike is capable of fast starts doesnt mean you need to neuter it. One of these days you may need all that acceleration to escape danger. If you dont want to go fast dont go fast.

 

Fewer teeth up front Lower the gearing -1 tooth Front = to about +2.83 teeth in rear. Average gearing change is + 2 rear.

Go down -1 rear do nothing to front higher Hwy speeds lower RPMS (HWY)
Go up +2 rear leave front alone (better power in twisties)
Go down -1 front leave rear alone (better power in twisties)

I am WAYYY over simplifying this... when you change the gearing you should go ahead and pay the $109-115 for a speedo healer. It will keep your speedo right as well as the odometer. Here are two links as well as a place to purchase.

http://www.sprocketcenter.com/search.asp?Keywords=VFR
Gear Ratio Chart - Sprocket Center

 

It is possible if the od. is right now and the speedo is off by 7-8%

 

Ok Thanks guys. So bitterpil according to u going down one tooth in the rear would be better then?
FJ12rydertoo I would be interested in getting that sprocket from you but would not have a clue what shipping would cost to here in Oz plus i know it would take a few weeks to get here & i get impatient LOL

 

Hmmm. I wasn't saying what was good or bad. I try to stay away from telling someone what to do. It is after all your bike and your money.
Honestly I think you will like stock gearing best. Especially if you ride non hwy curvy roads. I do not think you will like the low-end response if you go - in the rear. If you must, maybe -1 rear. Again that is for HWY cruising.

Are you sure your bike is geared STOCK?

 

I know how that goes, I'm usually watching the driveway the day after I order something. :smile:

I didn't even think to check your whereabouts. Oops. The offer still stands if you're interested. :biggrin:

 

My bike's odometer was dead on, but the speedometer was off by about 8% so when I changed the countershaft sprocket my speedometer was just about right, but the odometer was now off by about 8%. It didn't bother me any as I have a bicycle computer on the bike so the speedometer being off is a non-issue.

 

If you set +1 front and -3 rear... That would be like going down -5+ rear.... not a good thing.



+1 front is like dropping rear -3 teeth(rounding)
-1 front is like going up +3 rear(rounding)

if you go -1 and +2 it is like going +5.8 rear ... it would be a wheelie machine.
Beat to make changes front or rear.
for what you are looking at -1 or -2 will drop RPMs. Remember that the same drop at 65 MPH is the same at 1MPH. You don't want to lose too much down in the low-end. So basically you will give up responsiveness for RPMs on HWY. JUST MY OPINION -->> I think you will prefer stock gearing . I cruise 80MPH at 5500RPMS.. with stock while retaining throttle response.

You are a 99 and I am a 06.. My stock gearing is 16 x 43... I am not sure of stock on yours.

Throttle response is a defensive mechanism while on the road on 2 wheels.


anyway... I wish you luck in whatever you decide. and It would be cool of you to share when done.

P.S. Also think if you change gearing get a speedo healer.

 

ok. From what yous are saying im kinda thinkin i might just stick with what i got & just get used to it. Im just not used to such a high reving bike & just feel its workin too hard. I think from memory at 100kms (approx 60miles) it sits about 4500. Not sure if its the stock sprockets on it but will go down & check soon.

 

Ok, just went & checked. The rear is 43 & the front is 17. Can anyone tell me if this is stock for it?

 

Gearing

Well it sounds like you have the same gearing as mine(gen 5) at 100klms,around 4500rpm.But bear in mind that the power is pretty lame at anything under 4000,so at highway cruising its pretty well the sweetest place to run.Any higher gearing will mean that the engine will labor,and you won`t have any throttle response to get you quickly out of harms way.
And as a side note I get about 380klms out of a tank(21ltrs) which for a fairly heavy 800cc road bike is really good.
You will get used to "higher revs" on the highway,and these motors are built to rev anyhow.
Just my 2 bob.

BTW Bega is a beautiful part of the world.You are a lucky bloke!:thumbsup:

Robby.

 

Yeah is great down here & some of the best motorcycling roads around. I go riding with some of the local Ulysses guys on the weekends. Im not quite old enough to join but they consider me an adopted member LOL

 

I was told by a credible source NOT to change the front cog on my Viffer, as it changes the rear geometry...

 

Start believing in K.I.S.S. (keep it simple ******) and stay stock.

Carry on ~

 

Are you pulling my leg? Are you checking your stock gauge against a bicycle computer?
You are suggesting that the stock Honda gauge is mis-calibrated.

Bonnet Boy,
The VFR Engine will suffer more chugging along below 4000 rpm than it will whining away at 10000 rpm, it is designed to spin fast.
I know the feeling though, I rode a Vtwin cruiser for a year and the transition back took a minute.
Dont worry, your engine loves 5,000 rpm.

 

I agree: the engine will be happier spinning than lugging.

You're pulling my leg, right? :smile: Of course the Honda speedometers show a higher speed than actual, they are designed that way, and have been since the 60's, but then so do all the Japanese bikes. I don't profess to know exactly why they do it, but they do. Most are about 5-8% optimistic.

 

sounds like stock for that year (at least it is listed as such). My bike(06 6th gen) stock is 16x43.

I have a 6 speed trans and 781cc. At 5500 RPMS in 6th gear I am 80-81 MPH. I am about 255 in the seat. I stuck with stock. I think the lag on the bike would be too much if I went -1 rear. I have thought about +2 rear for fun on the back roads.

 

Yep, my speedo is about 5-7 mph higher than reality.