Any way to easily increase top speed?

[bkh2]

So here in Canada, BC, speed limits rarely go over 100 km/h (60 mph). In fact, the vast majority of highways that I have been on are 80 km/h (50 mph). On a trip to the States (traveling on the I-5), the speed limit for non-industrial vehicles was 70 mph (113 km/h). My friend was driving around 150 km/h (Honda Civic), which is pretty close to the maximum speed of a Ninjette, correct? At that speed, we were still pretty much going the same speed as traffic, which makes me kind of curious. Of course, where I live, Ninjettes will do absolutely fine on the highways, but in the States, do any of you feel lacking in top speed? Does a simple sprocket change yield higher top speeds?

[choneofakind]

no. the ninjette is fine on the freeways. it will do 80 all day long

[Live2ride]

I've taken my bike up to 100 mph before and held it on the highway; my step brother got his to 125 mph indicated once. I can hold 90mph easily while going down the highway though I rarely ever find the need to go that fast. I doubt a simple sprocket change will do much in your case. The best way I have found to increase top speed is to tuck in as far as I can to reduce wind resistance.

[ninja250]

You'll be fine on the stock gearing doing 100mph all day.
I have no idea why anyone would ever decrease the ratio on the ninja and make the little engine work harder unless they were going for top speed and have a while to get there.
Read as, climbing freeway on-ramps is gonna suck.

In fact I have heard decreasing the front sprocket by one tooth (increasing ratio) makes this bike come alive and it will feel like it should feel power wise. It should still do 80mph in theory if it can do 100 stock and you only decrease one tooth in front. (I didn't do the math, forgive me if I'm way off) but you will get much nicer acceleration and still have some top speed left.

It is a six speed transmission, after all.

[coondog]

Running 80+ in top gear @11k rpm+ and this bike loves you. Forget all the 100+mph bullshit now as well as later, do yourself a favor.

[bkh2]

Thanks for all the comments. To clarify, I was just curious and was not planning to change my sprockets. I've heard that some people reduce the ratio to make the bike quieter? Also I have no need to exceed 60mph (according to speed limit signs, anyways ) since highways here are usually under 60 mph. Has anyone here changed their sprockets, and if so, for what reason?

[greatwhiteninja]

80 all day long.. occasionally 90.

[Kurgan]

I've been above 95 one or twice trying not to be late for work, luckily the cop that saw me was on the other side of the freeway and my exit was only a half mile away, no time for him to turn around before I disappeared

[greg737]

fold the mirrors back, chin at the tank, back flat, knees and elbows in... twist throttle.

[greatwhiteninja]

oh!, should be said if your 300 lbs, top speed is 80 stock gearing.. 90 with 15t, ask me how i know..lol!

[KJohnson21]

BTW - The speedometer is "Optimistic"

[kaiserz]

Go to the gym.

[greatwhiteninja]

no thank you ..

[kaiserz]

That's what I did.

[bkh2]

Haha I think I weigh 145 lbs, 5' 7". I guess tucking is the easiest way to go faster haha, but were you serious about folding mirrors :O?

[greatwhiteninja]

Originally Posted by kaiserz

That's what I did.

I use to go. Don't anymore. I'm naturally a big Guy, 275 Is the lowest I've ever been, but I did alot of weight lifting and playing football so the bigger The better

[2011Ninja250R]

Ride naked. Tuck hard. Eat beans.
Or go buy an R1.

[kaiserz]

Originally Posted by bkh2

Haha I think I weigh 145 lbs, 5' 7". I guess tucking is the easiest way to go faster haha, but were you serious about folding mirrors :O?

I guess folding the mirrors will increase your top speed by just a bit because it's gonna be more aerodynamic. but I wouldn't do it...

Originally Posted by greatwhiteninja

I use to go. Don't anymore. I'm naturally a big Guy, 275 Is the lowest I've ever been, but I did alot of weight lifting and playing football so the bigger The better

I know the ladies will agree with you on that

[greg737]

Originally Posted by bkh2

Haha I think I weigh 145 lbs, 5' 7". I guess tucking is the easiest way to go faster haha, but were you serious about folding mirrors :O?

Well, it may be unforgivably geeky, but when I finished my fuel injection conversion project on my 2005 EX-250 and I was exploring it's capabilities, I did my top-speed check-out with the mirrors folded back (streamlined).

Thank goodness for the police-free nature of I-90 in North Idaho.

(but in my defense, I got the folded-mirror idea from other EX-250 top-speed nut-cases. There are even guys who remove them and also install flush-mount turn signals, so I'm not too over the top by comparison)

[greatwhiteninja]

Originally Posted by kaiserz

I know the ladies will agree with you on that

Married, so yes

[rusninja]

Originally Posted by greatwhiteninja

I'm naturally a big Guy, 275 Is the lowest I've ever been

i feel sorry for your mom XD jk jk you were a baby once apon a time so you had that climb. :P

[CZroe]

Originally Posted by ninja250

You'll be fine on the stock gearing doing 100mph all day.
I have no idea why anyone would ever decrease the ratio on the ninja and make the little engine work harder unless they were going for top speed and have a while to get there.
Read as, climbing freeway on-ramps is gonna suck.

In fact I have heard decreasing the front sprocket by one tooth (increasing ratio) makes this bike come alive and it will feel like it should feel power wise. It should still do 80mph in theory if it can do 100 stock and you only decrease one tooth in front. (I didn't do the math, forgive me if I'm way off) but you will get much nicer acceleration and still have some top speed left.

It is a six speed transmission, after all.

Top speed doesn't change. It's still limited by HP vs. wind resistance (Newtonian physics). Acceleration and torque change as well as the RPMs for a given speed, but not top speed. Weight does not limit top speed either. It just changes the amount of time it takes and usually goes hand-in-hand with increased wind resistance.

[greatwhiteninja]

Originally Posted by rusninja

i feel sorry for your mom XD jk jk you were a baby once apon a time so you had that climb. :P

......

[Skippii]

Originally Posted by bkh2

Any way to easily increase top speed?

Nitrous is the easiest way, if you don't count the installation.

[ninja250]

Originally Posted by CZroe

Top speed doesn't change. It's still limited by HP vs. wind resistance (Newtonian physics). Acceleration and torque change as well as the RPMs for a given speed, but not top speed. Weight does not limit top speed either. It just changes the amount of time it takes and usually goes hand-in-hand with increased wind resistance.

Are you sure top speed doesn't change with gearing?
I'm not questioning you really, just for some reason doesn't sound right to me.
I could be and have been known to be wrong though!
hehe

[Skippii]

Originally Posted by ninja250

Are you sure top speed doesn't change with gearing?
I'm not questioning you really, just for some reason doesn't sound right to me.
I could be and have been known to be wrong though!
hehe

If you keep hitting the rev limiter, then yes, increasing gearing will increase top speed. If you're not hitting the rev limiter, you won't go faster.
That's the simple answer.

The more complicated answer is that to maximize top speed, you set your gearing so that your top speed is achieved at the same RPM as maximum horsepower. This, of course, means either lots of trial and error, or knowing what your top speed is for a certain gearing before gearing it that way, which has to do with fluid dynamics.

[alex.s]

add a 7th gear?

i know someone who cruises the ninja around at 100mph all day...

[ninja250]

Originally Posted by Skippii

If you keep hitting the rev limiter, then yes, increasing gearing will increase top speed. If you're not hitting the rev limiter, you won't go faster.
That's the simple answer.

The more complicated answer is that to maximize top speed, you set your gearing so that your top speed is achieved at the same RPM as maximum horsepower. This, of course, means either lots of trial and error, or knowing what your top speed is for a certain gearing before gearing it that way, which has to do with fluid dynamics.

Come again?

[rockNroll]

Originally Posted by bkh2

So here in Canada, BC, speed limits rarely go over 100 km/h (60 mph). In fact, the vast majority of highways that I have been on are 80 km/h (50 mph). On a trip to the States (traveling on the I-5), the speed limit for non-industrial vehicles was 70 mph (113 km/h). My friend was driving around 150 km/h (Honda Civic), which is pretty close to the maximum speed of a Ninjette, correct? At that speed, we were still pretty much going the same speed as traffic, which makes me kind of curious. Of course, where I live, Ninjettes will do absolutely fine on the highways, but in the States, do any of you feel lacking in top speed? Does a simple sprocket change yield higher top speeds?

Yes, it lacks some. There are times and places where I would like to be able to ride 85mph without taking forever to get there, without the engine screaming so hard, and still have some throttle response left over in case I'd like to whip it up to 90 mph for whatever reason I might see fit. I don't have one of them 100mph versions, sadly

[alex.s]

Originally Posted by ninja250

Come again?

cause gases fall under fluid dynamic laws... any discontinuous substance held together by tension can typically be described with fluid dynamics... when dealing with cars and stuff they usually call it aerodynamics but its the same thing. just different coefficients ... in other words, you know your drag coefficient of the vehicle, so you know how much power you need to move through a certain substance (air) at a given speed, so you figure out what gear ratio would put you at your top speed for the power put out by your engine at that rpm... i guess that still doesn't make a whole lot of sense does it

[KJohnson21]

Originally Posted by alex.s

i know someone who cruises the ninja around at 100mph all day...

Originally Posted by KJohnson21

BTW - The speedometer is "Optimistic"

[alex.s]

not me... but, GPS don't lie

[CZroe]

Originally Posted by ninja250

Come again?

Exactly why I limited myself to simple Newtonian physics (equal and opposite reaction; big attracted to small, etc) and not more complex physics. :P

[CZroe]

Originally Posted by ninja250

Are you sure top speed doesn't change with gearing?
I'm not questioning you really, just for some reason doesn't sound right to me.
I could be and have been known to be wrong though!
hehe

It's like using a pulley or changing gears on a bicycle. It takes a certain amount of energy to take yourself and the bicycle over a hill. When certain complicating factors are ignored, it takes the same energy no matter the gear selected (equal and opposite). It takes the same to push it too except you are now also expending energy supporting yourself and such on top of the energy to carry the bike.

The gear selected doesn't make it take more or less energy to get over a particular hill, just more or less pedal rotations (RPMs). A complicating factor would be that your legs are exposed unlike the interior of an engine so more pedaling encounters more wind resistance and expends more energy. It may seem that it takes more energy in a higher gear but it simply takes more for a given moment while getting equivalently more distance, just like a pulley versus a straight rope (pully equals more energy over greater distance with much less torque required). This is obvious when you see that cars are more efficient in a higher gear (less rotational losses).

[Skippii]

Originally Posted by ninja250

Come again?

It doesn't increase top speed.

[ninja250]

I can't go as fast with my stunt gearing. It changed top speed.
Bike is revving through roof at 85mph(gps). Use to do 100!
Lots of acceleration though! Rather nice.
Only downside is the higher RPM and more shifting but it's nicer to ride this way.
Feels like more authority and puts the smack down.

I think I'm gonna do the ziptie mod.. will feel cleaaaaan.

Jet with your current gearing you should be able to do well over 100mph. (gps) 15/38?

[CZroe]

Originally Posted by ninja250

I can't go as fast with my stunt gearing. It changed top speed.
Bike is revving through roof at 85mph(gps). Use to do 100!
Lots of acceleration though! Rather nice.
Only downside is the higher RPM and more shifting but it's nicer to ride this way.
Feels like more authority and puts the smack down.

I think I'm gonna do the ziptie mod.. will feel cleaaaaan.

Jet with your current gearing you should be able to do well over 100mph. (gps) 15/38?

It's probably better to say that the rev limiter limited your top speed and not the gearing. Your gearing just arranged the meeting.

I was doing 105 indicated with room to spare at 14:45, 15:41, and 15:43. I haven't tried to go past 95 indicated with 15:38, but it could certainly do it going flat or downhill. The RPMs are finally noticably lower! Even at 15:41 it was still under 37MPH in top gear at 4,000 RPM, which is exactly what people report to be their maximum indicated speed was during bone-stock manufacturer-style break-in.

[ninja250]

I never bounced off the rev limiter.
My ear limited my revs. I can just tell when it's close.
I don't do the bounce... it's always bugged me haha.

Although I guess that's what it's there for, for me to use!

I thought the stunt guy today was going to kill his limiter. He bounced off it 2000 times a minute.
Then proceeded to overheat his bike.

The gears were definitely the limiting factor in my top speed.
As with an R/C car or R/C helicopter.
To change the headspeed, you change the gears.
If the R/C car isn't going as fast around the track as others with the same motor, change the gears.
Gearing does effect output speed. I don't see how much aerodynamics has to do with it.

My bike only does 85ish now when it used to do 100mph, all that I changed was the gears.

If you put tiny gears on it will take a long time to get to a high speed.
For me I have big gears and I get to a lower speed very fast.

If you use less RPM to make the same speed on the highway, that means you have more RPM to make more speed. (Until such point as the bike becomes over-geared and will no longer accelerate)

[CZroe]

Originally Posted by ninja250

I never bounced off the rev limiter.
My ear limited my revs. I can just tell when it's close.
I don't do the bounce... it's always bugged me haha.

Although I guess that's what it's there for, for me to use!

I thought the stunt guy today was going to kill his limiter. He bounced off it 2000 times a minute.
Then proceeded to overheat his bike.

The gears were definitely the limiting factor in my top speed.
As with an R/C car or R/C helicopter.
To change the headspeed, you change the gears.
If the R/C car isn't going as fast around the track as others with the same motor, change the gears.
Gearing does effect output speed. I don't see how much aerodynamics has to do with it.

My bike only does 85ish now when it used to do 100mph, all that I changed was the gears.

If you put tiny gears on it will take a long time to get to a high speed.
For me I have big gears and I get to a lower speed very fast.

If you use less RPM to make the same speed on the highway, that means you have more RPM to make more speed. (Until such point as the bike becomes over-geared and will no longer accelerate)

The bolded part is not the case at all unless you are talking about artificial limits (rev limiter or your response to your own ears ). Think about it: At the original gearing, what "force" stops you from being able to rev higher and continue accelerating infinitely? The answer is a sum of the rolling resistance and wind resistance. When you change gears, the torque and rolling resistance changes for a particular gear so the output at different RPMS/gearings are NOT equivalent, as indicated by the decreased or increased acceleration. If you changed your gearing like mine, the engine is no longer capable of equalizing against the same wind resistance at the same RPM because it hits that same limiting wall before getting to that RPM.

IOW, the same wind resistance is enough to overcome the output at a different given RPM. Let's say that you geared it like mine: The same force that stops you from accelerating infinitely will stop you at a lower RPM because it has less torque. It's exactly the same reason it's easier to stop the tire and stall in a high gear. It's EVEN easier to stop the tire and stall when you tighten the ratio.

Your top speed is lower because you are are out of RPM headroom, which is a limit of what is safe for the engine. Because mine is not capable of redlining in top gear anymore due to wind resistance alone, we know that RPM headroom is NOT the limit we should be looking at for gearing changes in general (most don't change in a way that would cause this). Imagine that redline was 30,000 for the same motor with the same HP and it simply wasn't capable of getting there no matter what gearing we selected and then you'll see that top speed is not directly dictated by redline: It's dictated by outside forces acting on the bike.

[Racer x]

I have been doing this for four years at Maxton . I have every gear combo 14 15 16 front. 45 ~41 rear and two rear tires 1/2 inch height difference. Plus 5th gear is is 1to 1 and 6th gear is .896 to 1 . It is VER easy to have to much gear. Going paste the power limit drops the rpm and then the speed will drop. That is the game.
I go on the dyno to figure out what Rpm makes the most power. Then because I have made over 100 passes I have an idea whay speed I want. Then I select the proper gear ratio.
Wind permittting the bike will run the number.


I have also used jockeys to ride my bike 40 lb lighter and no real difference in speed.