Weight reduction performance improvement ex250

[azian4lifz]

What can I replace to make it weigh less? Unnecessary stuff on the pregen ex250 I should be aware of to remove? If there is a post on this already, can somebody redirect me or link me? Thanks. Pat

[alex.s]

it'll be much lighter if you remove that heavy engine

[ninjamunky85]

que @alex.s with the sarcastic answer. lol

And it's more about what can you remove other than what you can replace. i.e. bodywork, guages, lights, maybe the back half of the seat and frame, the rear brake and caliper, and if you're really good the front wheel and forks.

[FvnnyL3tt3r1ng]

Center stand is a pretty simple one. Stock bars. Removing the fairings is going to cost you speed and acceleration so that's your call. Don't really know what else I mean those are the easiest....

[crazymadbastard]

Put helium in the tires, make sure they purge all the air first, the moisture in ambient air expands at much different rates. Helium is lighter and more consistent throughout the temp range. Only problem is if you get a blowout you start talking in a high pitched voice.

If you are fat, you may want to start there. Jus sayin...

[crazymadbastard]

also no leathers, just boxers, nothing else. Thong only for better aerodynamics. Oh and shave...

[alex.s]

rear brake does not weigh much and can save you if the front goes out.

battery is a waste of weight and space. replace it with lipo or remove it and go push-start only. if push-start only, remove the starter also.
chain and sprockets can get lighter... 415 chain
get a lighter exhaust
pods
bodywork is heavy, take it off
don't put so much gas in the bike
the cheap coils are heavy and take up too much space, go coil-over.
you don't need gauges.
you don't need a coolant surge tank.
or any evap or filter stuff.
you can replace the top engine/radiator mount bracket with a piece milled from aluminum. saves 5lbs.

most important:
lose some weight, fatty.

[choneofakind]

How much do you weigh?

[Racer x]

Not much. The stock exhaust is the biggie.
Center stand, air box and stock bars for aluminum clip ons. If you race the lights and rear break is next.

[quarterliter]

"battery is a waste of weight and space. replace it with lipo or remove it and go push-start only. if push-start only, remove the starter also."

Doesn't the 250 need a battery to run right? I disconnected my battery once when the bike was running and it did all sorts of weird stuff.

[alex.s]

Originally Posted by quarterliter

"battery is a waste of weight and space. replace it with lipo or remove it and go push-start only. if push-start only, remove the starter also."

Doesn't the 250 need a battery to run right? I disconnected my battery once when the bike was running and it did all sorts of weird stuff.

it needs a very small battery to keep the CDI going between stator pulses. very small.

[SDx]

Originally Posted by alex.s

the cheap coils are heavy and take up too much space, go coil-over.

can you go into a little more detail about this

[alex.s]

no

[Lychee]

Originally Posted by quarterliter

I disconnected my battery once when the bike was running and it did all sorts of weird stuff.

Not a good idea for your Regulator/Rectifier's health.

Originally Posted by alex.s

the cheap coils are heavy and take up too much space, go coil-over.

Originally Posted by SDx

can you go into a little more detail about this

Originally Posted by alex.s

no

[Kokosun]

What kind of a difference does weight really make? Assuming that the wet weight of a ninjette is 350lbs-360lbs, how does each additional 1lb of weight impact the overall performance of the bike? Is there anybody that can do the math in terms of loss/gain of power based on weight increase/decrease. Clearly, it's going to have an impact, but how much of an impact. I read (somewhere) that 10lbs translates to a power loss of 1hp. But, that just doesn't make sense. A 150lb rider would subtract 15hp ... I don't think so!

[Racer x]

On the drag strip for a1/4 of a mile it matters. And could be easy to figure out. Google a 1/4 mile et calculator and fill in the blanks.

For fuel economy in a hilly area it would be a factor but hard to measure. For top speed it only affects the time it takes to reach the speed. Not the top speed.

[Kokosun]

Originally Posted by Racer x

On the drag strip for a1/4 of a mile it matters. And could be easy to figure out. Google a 1/4 mile et calculator and fill in the blanks.

OK. I entered the numbers in a calculator (for my pre-gen 250).

With no rider the calculator estimated that the 1/4 mile time would be 13.63s. With a 100lb rider it estimated 14.821. Interestingly, the manual estimates 1/4 mile at 14.59s (but I couldn't find what the assumption is in terms of weight). I then went ahead and entered weight variations at 10lb increments.

The difference becomes smaller as weight increases (presumably because it's a lower percentage of the total weight) but it averages out at roughly 0.1s for every additional 10lb.

A 200lb rider is around 0.39s slower than a 160lb rider, who is around 0.4s slower than a 120lb rider. Just to add a perspective, a 200lb rider is around 0.3s faster on a 300 than on a 250.

Doesn't seem like a lot, but I'm guessing that on a circuit, that loss of acceleration would add up to a lot of time - maybe a second a lap per additional 10lb.

So ... switch from Big Mac 'n' fries to Slimfast 'n' diet coke!

[Racer x]

Since no one drag is drag racing 250 ninjas In the real world lap times are the only real reason to go overboard on weight reduction.
And most race orgs look at that in the rules.

[Motofool]

Originally Posted by azian4lifz

What can I replace to make it weigh less? Unnecessary stuff on the pregen ex250 I should be aware of to remove? If there is a post on this already, can somebody redirect me or link me? Thanks. Pat

Here you are, Pat:

http://www.ninjette.org/forums/showthread.php?t=117501

[Motofool]

Originally Posted by Kokosun

What kind of a difference does weight really make? Assuming that the wet weight of a ninjette is 350lbs-360lbs, how does each additional 1lb of weight impact the overall performance of the bike? Is there anybody that can do the math in terms of loss/gain of power based on weight increase/decrease. Clearly, it's going to have an impact, but how much of an impact. I read (somewhere) that 10lbs translates to a power loss of 1hp. But, that just doesn't make sense. A 150lb rider would subtract 15hp ... I don't think so!

For zero speed to top speed, the mass or weight is the critical thing (assuming that you cannot increase the torque produced by your engine), because:

Acceleration = Top speed / Time = Torque at the rear tire / Total weight (rider + fluids + bike)

Hence, the acceleration (time to reach top speed or speed reached at certain distance) is inversely proportional to the total weight.

However, as speed increases, the aerodynamic drag (a resistive force that opposes to the torque at the rear tire) increases at a square rate.



http://en.wikipedia.org/wiki/Drag_coefficient

For that reason, things that reduce the coefficient of drag of rider + bike, reduce that critical resistive force at speeds above 60 ~ 70 mph.

Finally, the HP produced by your bike is simply the product of that torque times the speed at which the rear tire rotates (which is the speed at which the bike moves forward):

http://en.wikipedia.org/wiki/Horsepower

HP = Torque at the rear tire x Speed

Again, as speed increases, the aerodynamic drag grows faster and even more torque is needed to overcome that force.
As your HP and torque are limited, a terminal speed (top speed for your specific bike) is reached, at which torque = aerodynamic drag (for a flat road).
You need much less HP to reach a top speed of 100 mph than to reach a top speed of 110 mph.