Speed help.

[DrunkenMistake]

I have just put on a 14t front sprocket and a 42 rear sprocket, and obviously this is going to ruin my speedo, so what I want to know can someone give me some kind of calculation so I can figure out my Real speed, the bike is a VFR 400 NC30 and is cable driven speedo from the front sprocket

EDIT: As mentioned by TT
'Bike: 1991 VFR 40 NC30.
Standard gearing: 15 Front, 40 Rear.

You just need to know where on the speedo a 'true' 50km, 70km, and 100km would be right?'

[The Stranger]

And I mean I speed and I need help, I actually enjoy it ;)

I have just put on a 14t front sprocket and a 42 rear sprocket, and obviously this is going to ruin my speedo, so what I want to know can someone give me some kind of calculation so I can figure out my Real speed, the bike is a VFR 400 NC30 and is cable driven speedo from the front sprocket

Go find a speed camera and make a series of passes at varying speeds, they'll do the rest for you.

[The Stranger]

And I mean I speed and I need help, I actually enjoy it ;)

I have just put on a 14t front sprocket and a 42 rear sprocket, and obviously this is going to ruin my speedo, so what I want to know can someone give me some kind of calculation so I can figure out my Real speed, the bike is a VFR 400 NC30 and is cable driven speedo from the front sprocket

Or you could use this.

[tigertim20]

And I mean I speed and I need help, I actually enjoy it ;)

I have just put on a 14t front sprocket and a 42 rear sprocket, and obviously this is going to ruin my speedo, so what I want to know can someone give me some kind of calculation so I can figure out my Real speed, the bike is a VFR 400 NC30 and is cable driven speedo from the front sprocket

The information he left out is as follows.
Bike: 1991 VFR 40 NC30.
Standard gearing: 15 Front, 40 Rear.

You just need to know where on the speedo a 'true' 50km, 7km, and 100km would be right?

[JimO]

The information he left out is as follows.
Bike: 1991 VFR 40 NC30.
Standard gearing: 15 Front, 40 Rear.

You just need to know where on the speedo a 'true' 50km, 7km, and 100km would be right?

borrow a gps from someone

[DrunkenMistake]

borrow a gps from someone

Yeah that is a good idea,
I might get my Mrs to drive infront of me at 50km then see what im reading and work out the % difference.

[pete376403]

Put a cat-eye or similar bicycle speedo on it. Would be as accurate as anything else if you install it correctlly

http://www.trademe.co.nz/Sports/Cycling/Parts-accessories/Computers/auction-378462903.htm

[DrunkenMistake]

Put a cat-eye or similar bicycle speedo on it. Would be as accurate as anything else if you install it correctlly

http://www.trademe.co.nz/Sports/Cycling/Parts-accessories/Computers/auction-378462903.htm

Also another great Idea, ill see if anyone comes up with some kind of calculation or something like that and go from there.

[JimO]

Yeah that is a good idea,
I might get my Mrs to drive infront of me at 50km then see what im reading and work out the % difference.

the car speedo will be out as well, probably reading high which is better than reading low if all else fails i have a tomtom you can borrow

[DrunkenMistake]

the car speedo will be out as well, probably reading high which is better than reading low if all else fails i have a tomtom you can borrow

I may get back to you on that actually wouldnt need it for much more than 5 mins, just need a reading at the likes of 50km to figure out the % then i can work out what it should be accross the board, I had my speedo indicating 120 when I took it for a blip to try it out with the new gearing, and I was most defiantly not doing 120 haha

[bogan]

http://www.gearingcommander.com/ will tell you all you need to know :D

[DrunkenMistake]

http://www.gearingcommander.com/ will tell you all you need to know :D

Urgh ignore what was said here, i got them all wrong.

[Sable]

Gearing has nothing whatsoever to do with your speedo reading smackhead.

[bogan]

Yah I seem it, it said that 9635rpm i should be doing 70 in first gear.

and at 4000rpm i should be doing 29.8km in first, So ill sit at 4000 tomorrow when I go to work and see what the dial says

you may find it easier to maintain speed, and get a more accurate reading in higher gears. That is a fairly massive change, what's the new rpm going to be at 100kmhr?


Gearing has nothing whatsoever to do with your speedo reading smackhead.

unless the speedo drive comes from your gearbox :facepalm: then the final drive ratio has a lot to say about it :bleh:

[DrunkenMistake]

Gearing has nothing whatsoever to do with your speedo reading smackhead.

-backhand- its not driven off the front wheel, it comes from the gear box

[DrunkenMistake]

you may find it easier to maintain speed, and get a more accurate reading in higher gears. That is a fairly massive change, what's the new rpm going to be at 100kmhr?
:

ill look in a moment, I could do 100km in first at 14,000 I have probably dropped my top from 210 to 180ish

[DrunkenMistake]

1st is NULL
2nd is - 11457rpm
3rd is - 9518
4th is - 8412
5th is - 7357
6th is - 6970

for 100km.

[bogan]

ill look in a moment, I could do 100km in first at 14,000 I have probably dropped my top from 210 to 180ish

that sounds fairly low ratio, and you're going even lower :blink: suppose it is a screaming V4 though (gotta get me one at some point)


1st is NULL
2nd is - 11457rpm
3rd is - 9518
4th is - 8412
5th is - 7357
6th is - 6970

for 100km.

thats a lot of revs for 6th! hope you have a nice exhaust on there.

[DrunkenMistake]

yah it seems kinda high thats why I am wondering how accurate the gearing commander is, and at the moment the whole lot is stock standard, I wanted to drop the top end as 90% of my riding is infact commuting to work down a nice long road with twisties, I cant do much more than 150 - 160 anyway so it just seemed practical to use that pent up V4 power at a lower speed

I am waiting for a full stainless race exhaust system to arrive, then I will get the carbs sonic cleaned, rejet myself, install the exhaust and new CDI and take it back to get balanced, then ill get it tuned when I have a little more money

[bogan]

yah it seems kinda high thats why I am wondering how accurate the gearing commander is, and at the moment the whole lot is stock standard, I wanted to drop the top end as 90% of my riding is infact commuting to work down a nice long road with twisties, I cant do much more than 150 - 160 anyway so it just seemed practical to use that pent up V4 power at a lower speed

I am waiting for a full stainless race exhaust system to arrive, then I will get the carbs sonic cleaned, rejet myself, install the exhaust and new CDI and take it back to get balanced, then ill get it tuned when I have a little more money

I haven't heard of gearingcommander getting it wrong yet, guessing you're doing a bit over 6k at 100 atm? Would have thought a 6 speed box would offer enough choices to keep the torque on, the VFRs have torque all over the range anyway don't they?

My advice would be don't swap to a new exhaust until you can afford to tune it as well. I did mine a few months ago, and took ages to get it tuned right, but felt worse to ride until it was properly tuned, well as good as I could get it with plug examinations anyway. I'd recommend a factory pro kit (if one is available) if you do it yourself as they give you the right bits, and damn good tuning tips.

[DrunkenMistake]

I haven't heard of gearingcommander getting it wrong yet, guessing you're doing a bit over 6k at 100 atm? Would have thought a 6 speed box would offer enough choices to keep the torque on, the VFRs have torque all over the range anyway don't they?

My advice would be don't swap to a new exhaust until you can afford to tune it as well. I did mine a few months ago, and took ages to get it tuned right, but felt worse to ride until it was properly tuned, well as good as I could get it with plug examinations anyway. I'd recommend a factory pro kit (if one is available) if you do it yourself as they give you the right bits, and damn good tuning tips.

Well the jetting part isnt an issue, on the 400greyimport forum there is an indepth step my step guide on how to do it and what to do etc etc, I would only need to ride it for a week/two before i could get it tuned anyway, I may just wait till I can do the lot in one bulk hit, still need to wait for the Zorst to arrive haha, torque is all over but there is a flat spot in the mid range which is common for viffers, there is an easy fix solution and that is adding another 0.5mm washer to the needle in the jets.

[bogan]

Well the jetting part isnt an issue, on the 400greyimport forum there is an indepth step my step guide on how to do it and what to do etc etc, I would only need to ride it for a week/two before i could get it tuned anyway, I may just wait till I can do the lot in one bulk hit, still need to wait for the Zorst to arrive haha, torque is all over but there is a flat spot in the mid range which is common for viffers, there is an easy fix solution and that is adding another 0.5mm washer to the needle in the jets.

What tuning do you mean if you aren't referring to the jetting then? For me by far the hardest bit to tune was main jet size, mainly because you have to go WFO for as long as possible before looking at the plugs.

[DrunkenMistake]

What tuning do you mean if you aren't referring to the jetting then? For me by far the hardest bit to tune was main jet size, mainly because you have to go WFO for as long as possible before looking at the plugs.

pretty much that, ill get it Dyno tuned then I get my print outs and that can fine tune everything, Im running i think its 100's and 115's front and back I cant remember for sure but It was highly recommended I do 120's and 122 main jets and it goes on to explain how to set the pilot jets etc but encase i mess something up (which I am good at) or forget to do something or miss something they can catch it and fine tune it, its a money saver really, the plan was to take the carbs off at home and take them in to be cleaned while I install the new CDI and pipes by that point they should be cleaned and what not, then ill get them back and rejet them and take the bike and carbs back to the shop in a van so I can get them balanced and reinstalled (the shop told me they have to add some extra pipes or something which will make it easier to actually get the carbs on and off because they are so hard) they are a pretty good shop and good bunch of guys so if they say its something they do then there must be a good reason to it,
it should save me alot of labour costs

[DrunkenMistake]

I apologise for my terrible punctuation and grammar Lmao and possible spelling.