Theoretical top speed after -1+2

[Banky2112]

Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator

So my buddy and I were looking into a sprocket change. A few members have mentioned their top speed around 143. Mine seemed to peak at 142 at an undisclosed location if you load the info into the selectors it will tell you that through our GEARING, we should make it 165. I think the reason we can't is the bike doesn't have enough in the pants.

So then I looked up what a -1 +2 would be, and turns out it's 145 (I'm pretty sure)

Anyways, that makes sense to me. And a member on the forum (feel free to jump in I can't remember your name) talked about being at a track day with a -1 +2 and other bikers saying he was hitting around 140 because they knew the speeds of the track and he was keeping up.

Anyone have any technical data to help me back this up.
This is my next mod so I found this all very interesting

 

[TorontoAlex]

Does the bike redline at 143? If it does, then you can change gearing to go faster, if it doesn't, changing gearing will mostly just change acceleration (and fuel mileage). If yamaha has done their job right, you will barely make it to top speed at redline so you're pretty much maxed out in power.

 

[Banky2112]

Does the bike redline at 143? If it does, then you can change gearing to go faster, if it doesn't, changing gearing will mostly just change acceleration (and fuel mileage). If yamaha has done their job right, you will barely make it to top speed at redline so you're pretty much maxed out in power.

I doesn't redline, your at about 10,600 RPM at 143 ish.....

I think with a nice set of fairings and a really small rider it could reach the 165 mark.

The reason I want to do a sprocket change is because 145 is PLENTY fast for me, and I would like to have a peppier 1st, 2nd, and some of 3rd.

So upping my "felt" torque but still being able to reach the same top speed the bike was already trying to do is a win win for me.

Your not losing any MPH, you just making it so that thats ALL you get lol.
And everything before that is just funner

 

[NoNine4me]

I doesn't redline, your at about 10,600 RPM at 143 ish.....

I think with a nice set of fairings and a really small rider it could reach the 165 mark.

The reason I want to do a sprocket change is because 145 is PLENTY fast for me, and I would like to have a peppier 1st, 2nd, and some of 3rd.

So upping my "felt" torque but still being able to reach the same top speed the bike was already trying to do is a win win for me.

Your not losing any MPH, you just making it so that thats ALL you get lol.
And everything before that is just funner

GSX-R 750, late model, top speed is 165 mph tested by the mags. 148 HP at crank, 127 at rear wheel, very aerodynamic. So we would need 15-20 more HP at the rear wheel to overcome drag. A full system, ECU reflash, maybe some internal R1 or FZ1 parts in the engine, and so on would be necessary to get 165 mph. Drag increases with the square of your speed so that's why so much more HP is necessary. Makes more sense to just buy a faster bike as it will cost so much to get our FZ8 to that level and even then it's not real comfortable at those speed; stability could be a problem there too without suspension upgrades.

Makes more sense to do as you suggested; your gas mileage will suffer but real world acceleration will be increased a lot although the bike may seem pretty "busy" on long freeway rides.

However I understand that just the ECU reflash alone removes a lot of the restrictions in the first three gears. I'll let you all know if this is true when I get my ECU back from Guhl in a couple of weeks.

 

[Banky2112]

Makes more sense to do as you suggested; your gas mileage will suffer but real world acceleration will be increased a lot although the bike may seem pretty "busy" on long freeway rides.

However I understand that just the ECU reflash alone removes a lot of the restrictions in the first three gears. I'll let you all know if this is true when I get my ECU back from Guhl in a couple of weeks.

Totally agree! And my ecu should be here Friday...... And then my forks and brakes and wheel have to go on...... then I can "test" her again

 

[Woody146]

Totally agree! And my ecu should be here Friday...... And then my forks and brakes and wheel have to go on...... then I can "test" her again

Sweet!! I think the ecu should make a considerate difference. I top out around 140 ish..maybe have seen 142 on a fresh paved blacktop on a ten mile straight..(kinda rare here) and I'm a big dude...6'2 240...I firmly believe that this bike can go 165. ...with some bodywork and a little asian guy..

 

[Woody146]

Sweet!! I think the ecu should make a considerate difference. I top out around 140 ish..maybe have seen 142 on a fresh paved blacktop on a ten mile straight..(kinda rare here) and I'm a big dude...6'2 240...I firmly believe that this bike can go 165. ...with some bodywork and a little asian guy..

Clip ons and a windscreen too...I think rider position is killing air flow

 

[RD GUY]

to do 165 w/ stock gearing would be imposible as the bike has a speed limiter in the ecu,therefore a reflash would be needed to removed it, I run -1 +2 and bike pulls like a mother****er all the way up to 260kpm,revs alittle more at highway speeds I would highly do the -1 +2 gearing ,my bike is stock w/yosh slipon and k/n went 10.98 in 1/4 mile

 

[Teslank]

to do 165 w/ stock gearing would be imposible as the bike has a speed limiter in the ecu,therefore a reflash would be needed to removed it, I run -1 +2 and bike pulls like a mother****er all the way up to 260kpm,revs alittle more at highway speeds I would highly do the -1 +2 gearing ,my bike is stock w/yosh slipon and k/n went 10.98 in 1/4 mile

i have fazer8 and i never ever got over 240.. and you can with a -1+2 ?? i have yosh r77 slipon

with -1+2 your bike have less top speed

you have the ecu reflash? i could do that

 

[Banky2112]

i have fazer8 and i never ever got over 240.. and you can with a -1+2 ?? i have yosh r77 slipon

with -1+2 your bike have less top speed

you have the ecu reflash? i could do that

Yes usually you would drop MPH if you did a -1 +2 , but since we can only do 140MPH to begin with (whether it be ecu or wind resistance or no more power to go any faster) you have nothing to lose.



Hold on a sec!
I'm not arguing the top speed limiter (if there is one)
I'm not arguing the reflash (as a good or bad idea)
I'm not arguing that you lose or gain MPH

I simply put up the website in the first post to show that if your cool with doing 140mph, than you could do a gear swap and get to 140mph FASTER, which is what I'm going to do.

If you want to know certain rpms for certain speeds AFTER a gear change this website can tell you what you will be holding!

Everything else is null in void unless it's contextual right?

 

[b-eock]

Correct. I get what you're saying. I myself liked the FZ8 highway gearing. And the -1 +2 gearing sounds fun. But we all know that the bike can go faster than 140...

Sent from my SAMSUNG-SGH-I727 using Tapatalk

 

[RD GUY]

been doing some searching and most reviews say 137mph w/106hp stock,all we are doing is guessing till someone actually radar gun's to get true reading ,or gps when spring hits I will post my findings .imo I don't think I lost any topend doing the -1 +2 it just gets there faster also went 11.20 1/4 w/stock gearing and 10.98 w/gearing change.

 

[b-eock]

You will always lose some top end if you change the gearing.

Sent from my SAMSUNG-SGH-I727 using Tapatalk

 

[Teslank]

so if i change to -1+2 i will get same top speed? but more acceleration?

 

[Banky2112]

so if i change to -1+2 i will get same top speed? but more acceleration?

Yes! But! Only because for whatever reason, our bikes can't reach their theoretical top speed of 165........

 

[Banky2112]

So check this out.

This is my last Dyno stuff after all my mods..... I picked up around 10 hp. And my "top speed" went from 142 (I did it) to 150 (Dyno top speed) but I didn't get even 1 more MPH when I tried again. Because on the Dyno there is no accounting for rider weight and wind resistance.

Does this help?

 

[b-eock]

I know the speedo is not completely accurate, but I've gotten it to read 161 straight flat open highway. No cross winds or opposing winds.

But that's one of the faster speeds that have been recorded. And I'm sure it's around 150 MPH in reality. I was tucked and tight.

And yes changing the front down and the rear up will increase acceleration. While lowering top end.

Sent from my SAMSUNG-SGH-I727 using Tapatalk

 

[Bajaedition]

first, our speedo is designed to be accurate around 60 mph

second, if you have ever done landspeed racing, you soon learn that the back wheel can be doing 165 and you can be doing 145, due to tire slippage

wind resisteance is a motherf(*%&r, and the amount o f horse power it takes to go 25 MPH faster is phenomenal. If the bike will not hit top RPM in 6th gear, it will not do it with a gearing change. It will take HP increase

 

[Bajaedition]

I think what we need to realize is lowering gear ratio increases quickness
and raising it increases top speed possibility

so if we started with a ratio of 3.73 and lowered it to 4.11 we are quicker at a set RPM but if we raise it to 3.23 we can go faster, it will take us longer to get to the speed however.

Now if we have the horse power to get to 142 mph, then no mater what we do to the gearing, we can only get to 142, and that means at 2 rpm or 8 rpm

Banky's dyno run shows the bike doing 149.9 before mods and 150.5, a 1/2 mph gain with the gain of 5 hp.
that is significant enough to show what it takes to spin that tire faster just on a dyno

remember, if the bike will only do 125 at 7500 rpm in 6th gear on a bike with a 10000 rpm redline, then it has maxed out its HP to resistance ratio. changing gears will only change where that ratio is met on the rpm range, as soon as it hits that ratio, it will not go faster

 

[Woody146]

Speedo healer would be a nice touch too to figure out TRUE top speed!