Down Gearing the VFR?

[retrofly]

hi
I wanna change it so it accelerates faster so a few questions

1.Go down one tooth on the front
2.Go down one tooth at the front and up one on the rear
3.How much top end is lost
4.Is it worth it?
5.How many teeth do both sprokets have as standard
6.Which/where should i get the new chain and sprokest from

Thanx for any replies

Luke
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[Deano]

retro, I've asked a few of the 400 racerboys about this and the seem to find dropping a tooth from the front and the back is what they use the most on tracks, but I've spoken to people who've -1 front and +3 rear and they say the difference is big on the acceleration but you loose about 10mph at top end but in london how often do you get to top end of 6th, erm..........never!

Hope that helps
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Dean Stone #777
EMRA 2012 final standings, Formula 600s 3rd, Superstock 600s 3rd.
www.triplesevenracing.co.uk: www.ljmotorcyclerepairs.co.uk www.gettaylored.co.uk BN RaceScience, Now officially run out of money to carry on racing

[TiN]

The standard sprockets on the VFR is 15/40. Apparently, dropping one tooth from the front is the equivalent of adding 2 or 3 at the back. If you drop a tooth from the front, then you can probably get away with using your current chain, but if you get a bigger rear sprocket then you'll need a longer chain.

I was informed that a smaller front sprocket isn't too good for the life of your chain (again, it's just what someone has told me, I don't know from experience), so it's more advisable to get a bigger rear sprocket and a new chain.

As Dean said, acceleration will be improved but top-end will suffer (but 400s are built for top-end speed anyway, so f*ck it ), and your speedo will over-read by about 10%.
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TiN
dotgems.net

[Kickstart]

Hi

Smaller front sprockets wear out chains mroe quickly. The smaller they are the quicker they wear. If you go down one tooth then you can probably get away with using the same chain but not certain, but go down one at the front and up one at the rear then you should be fine. However if you stick an old chain on new sprockets then they will wear out more quickly

All the best

Keith
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[WildGoose]

are the speedo's measured from the sprocket on your 400's then?
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[Deano]

I think they are! I was told if you change your gearing it affects the following, the speedo you will not be accurate you will be travelling slower than you clock indicates, you will constantly be hitting high revs without a thought which leads too more engine wear and more fuel consumption but not a massive difference though!
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Dean Stone #777
EMRA 2012 final standings, Formula 600s 3rd, Superstock 600s 3rd.
www.triplesevenracing.co.uk: www.ljmotorcyclerepairs.co.uk www.gettaylored.co.uk BN RaceScience, Now officially run out of money to carry on racing

[WildGoose]

err, your engine isnt gonna me damaged by high revs, as long as you dont exceed the red line

engines perform there best at high revs and are designed to be run as such, as long as the engine is warm, it wont do any damage

in fact it really annoys me people who dont rev there bloody bike, it seems like a waste, i was following a fazer in town and pulling away in first, he popped it into 2nd and subsequently 3rd and 4th before we even got to 25mph, and i was stilll in first, it was quite frustrating
____________________
So in other words, he stopped you for being flagrantly in posession of a motorcycle in direct contravention of the Hippies, Darkies and People Whose Face I Don't Like The Look of (Police Powers) Act. 1976

[Deano]

@ Goose

were does the expression of "thrashing your bike" come from i've always thought that means that its causes more engine wear, I didnt say that it was going to damage your engine there is a difference in between the 2 you know.....


P.S
I'm not trying to start an argument
____________________
Dean Stone #777
EMRA 2012 final standings, Formula 600s 3rd, Superstock 600s 3rd.
www.triplesevenracing.co.uk: www.ljmotorcyclerepairs.co.uk www.gettaylored.co.uk BN RaceScience, Now officially run out of money to carry on racing

[G]

I've always taken 'thrashing your bike' to mean riding hard etc (doesn't have to involve high revs, just pushing it etc) However some (noteably 2 strokes) bikes do work better if they are revved more, because they are designed to work best like that.

If you have a digital speedo then you can get 'yellow boxes' which convert the signal to whatever you want using a set of dip switches.

[craigT19]

yeah when i say im going out for a thrash, i tend to mean hitting some twists going as fast as i can etc,

also G dont v4s ride like 2strokes in the way that at low revs they got no power they ned to be "wound up" to a sertain extent?
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[TiN]

[craigT19]

ok

ive never been on a v-4 bigger than 400cc
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Bikes owned :- 2001 nsr125, 1999 zx6r, 2006 yzf-r1, 2009 xmax 250, 2012 yzf-r1, 2015 MT-07
Current bike : - 2016 MT-10
BCF member pops. sadly missed 1945-2003

[G]

Errr... AFAIK low down power (/tourque) has more to do with size per cyclinder (and bore/stroke) than the actual configuartion of the engine.

My exapmple of 2 strokes is because, AFAIK again, 2 stroke exhausts are tuned for best performance at a certain rpm range, which will obviously be high rpm on a sports bike. Obviously there are similar things on 4 strokes (thus EXUP valves etc), but not to such a great extent.

[TiN]

[Demonic69]

I can't really see any bike that runs well at low revs. All sports bikes, tourers and ST's will run better around/after 7krpm. That doesn't leave you much if you think thrashing your bike is gonna damage it.
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[JimboJ]

im thinking of doind this(i know another idea ) but i dont use top speed at all cos its unconfortable. i want as much accel as possible . the rear is -36 and thr fron is 14 i think. also thers a flat spot at 5000 revs which since ropey highlighted it to me its pissing me off.
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[Robby]

craig - ever head of a VFR750 or 800, or a pan european? both V4s over 400 cc.

and luke - i just went down one on the front, got a new chain too but its the same length, and going up more on the back shouldn't be a problem cos theres miles of adjustment there.

[WildGoose]

nah its cool dean im not starting an arguement either

its just people always seem to be worried about damaging there engines, and they seem to forget that engines are dirty, noisy, in-efficient, and all they do from the time they are created is start to die, they are constantly wearing out, and i dont think the difference between high revs and low revs really makes a lot of difference to engine life

i could be way off here so i'll allow keith or someone to state the facts
____________________
So in other words, he stopped you for being flagrantly in posession of a motorcycle in direct contravention of the Hippies, Darkies and People Whose Face I Don't Like The Look of (Police Powers) Act. 1976

[Kickstart]

[craigT19]

[Robby]

i thought you said you've never seen a v4 over 400cc, not ridden one...

[Doddmaster]

[retrofly]

hi
so how would i go about getting these chain and sprokets cause they aint standard? can i phone up places and get them to custom make me a set?

Luke
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"The food was not undelicious"
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[Deano]

@ Luke
B&C Express are the UK Renthals and Arrow Distrubutors, so ring them, Im soz I've lost the link, sprockets are dead cheap something like 15 - 20 notes each and you have a choice of anodised ones aswell but the chain will set you around £50 .
I think stew knows the web links so ask him.....
____________________
Dean Stone #777
EMRA 2012 final standings, Formula 600s 3rd, Superstock 600s 3rd.
www.triplesevenracing.co.uk: www.ljmotorcyclerepairs.co.uk www.gettaylored.co.uk BN RaceScience, Now officially run out of money to carry on racing

[Phoenix]

Goose, engines do wear more quickly at higher revs. The bikes that tend to last the longest are low revving ones, a Diversion for example has an 8,5K redline I think. One of the major reasons car engines last so much longer than bikes is because they rev so low in comparison. Thrashing in my opinion and interpreted in the context it's usually used means sustaining high revs most of the time and constantly giving it handfuls of throttle. A bike that redlines at 14K will as a rule last longer if you usually rode it around at 7K, obviously taking it higher every now and then than if you constantly kept it at 10K rpm.