Is the Pre-gen 250 still a capable bike?

[s2kenny]

Hello everyone,
I started off on a 2008 Ninja 250r, then moved up to a R6, CBR600rr. Got real comfortable on the CBR600RR, had some Q2 tires on them and it handles like a dream. I recently got into a major crash with the CBR and it's completely totaled. I'm recovering from the crash, and missing riding already.

My girlfriend has a pre-gen 250, and I was wondering if it would still be capable as a canyon carver /track bike.

What should I put on the bike to make it more suitable for fast riding? I'm looking around for the best tires that are made for the 250, and maybe switching up the suspension somehow.

Thanks!

[Nemesis]

Personally I think it's still capable and comparable to the New-Gen. I'm not sure if the rims are interchangeable but if they are I'd upgrade the pre-gen rims to the new-gen rims. Everything else is essentially the same.

[s2kenny]

Originally Posted by Nemesis

Personally I think it's still capable and comparable to the New-Gen. I'm not sure if the rims are interchangeable but if they are I'd upgrade the pre-gen rims to the new-gen rims. Everything else is essentially the same.

Great, I figure the engine would be comparable. But I'm not sure about the forks/brakes/shock.

How come you prefer the new-gen rims?



I'm mostly concerned with brakes/suspension. The ninja 250 definitely doesn't stop as quick as the big 600's, and the lever feel is really soft.

[Nemesis]

Oh, I forgot about the rearshock on the new-gens but I believe everything you can upgrade on the new-gen you can do the same for the pre-gens.

The 17" rims > 16" rims in terms of cornering (<--guys, correct me if I'm wrong...I don't know everything LOL). Also, variety of tires sizes to choose from, and availability is abundant on the 17" rims.

Brakes...eh, they felt the same to me. But that's just me.

[Racer x]

almost nothing is interchangeable from the new 08-12 bikes to the older 2007 on back. That said there is a couple decades worth of upgrades that can be done to the older bikes.

I would start with a call to race tech to redo the suspension . then get new tires. There is plenty you can do. Just search the forum and set a budget. Itis easy to get carried away.

[s2kenny]

Great thanks, any hope for the front brake?

[Racer x]

That I don't know.

[cerberusrex25]

Originally Posted by Nemesis

Personally I think it's still capable and comparable to the New-Gen. I'm not sure if the rims are interchangeable but if they are I'd upgrade the pre-gen rims to the new-gen rims. Everything else is essentially the same.

Not a straight swap, specially the back tire since the center hub is wider and the pregen caliper gets in the way. Also the swingarm on the pregen is very narrow. Both gens run on the same sprocket ratio.

Originally Posted by Nemesis

The 17" rims > 16" rims in terms of cornering (<--guys, correct me if I'm wrong...I don't know everything LOL). Also, variety of tires sizes to choose from, and availability is abundant on the 17" rims.

Dunno about the cornering, but there is a lot of Sport bias tires for the pre gen, in fact more than there is for the new gen( as far as options go).

Originally Posted by Racer x

almost nothing is interchangeable from the new 08-12 bikes to the older 2007 on back.

This is also true, not everything new gen will fit the pregen. But as far as a swinger swap goes, I have confirmed it is a straight swap. I will confirm about the front wheel soon, I think the rotors differ so that might require some elbow grease.

[Racer x]

Yup the swing are will go . THEN you can or have to change the rear rim and brakes. Change the front fork and you can change the front rim and brakes.

I put a pre gen engine in a new frame . But had to change a bunch of stuff.. I guess I should say it is all the same only different.

[cerberusrex25]

Awesoooooome, good to know all I have to do is a fork swap. Yeah I was quite amazed at how stiffer the new gen shock is, it supports my big butt better now and it sits a bit taller.

[Racer x]

I have not done the fork swap yet.SO don't hold me to it. But It "looks" like the head set is the same/

I have 1988 250 ninja and I had a 2003 . And I have my 2008 .The soft suspension is the only thing I don't like about the pre gen bike. The pre gen bike has more power on top end also.

[cerberusrex25]

Yes this is true, they are quite soft on the suspension side. Do you know of any good 2 into 1 exhaust systems for the pregen?

[s2kenny]

Originally Posted by Racer x

I have not done the fork swap yet.SO don't hold me to it. But It "looks" like the head set is the same/

I have 1988 250 ninja and I had a 2003 . And I have my 2008 .The soft suspension is the only thing I don't like about the pre gen bike. The pre gen bike has more power on top end also.

A set of springs for the fork, and a different shock would solve the soft suspension though right?

I'm also not a big fan of the soft suspension. I get too much nose dive when I brake hard.

[Racer x]

I have an old kerker on my 88 . Area p just came out with one I think . There was also a muzzy .The problem with the 2 in to 1 for a pre gen is you have to remove the center stand.

[copperaxe]

I can vouch that the pre-gen can be a competitive bike vs. the new Ninja 250; I have one that I am racing, and I got info, etc. from a guy in Georgia who won races on his pre-gen.

The key mod is to swap the wheels, and forks if desired. Get fork springs for your weight. Get an aftermarket shock or a modded shock. Get the Area P exhaust system, it is the best option! Adjust the ergos as necessary. Then ride the heck out of it!

It is good to know the swingarm is a direct swap, but a little machining and welding will enable the stock swing arm to wark with the new 17" wheels.

[PlaneGuy]

Originally Posted by s2kenny

Great, I figure the engine would be comparable. But The ninja 250 definitely doesn't stop as quick as the big 600's, and the lever feel is really soft.

When was the last time you changed the brake fluid and bled the brakes? Also a sport/racing pad compound will do wonders.

And after you do the fluid, bleed, and pads, if it is still spongy, it is time for new brake lines. I don't know if they make them but stainless steel brake lines firm them right up.

Brian (PlaneGuy, The Geezer, Pinky)

[Alex]

Yup - getting the system up to snuff (pads, fluid, line as needed) will optimize it, but the new-gen still has a larger disk and a slightly better quality caliper. When both versions are at the same level of care, the new-gen bike will still have somewhat better brakes.

[Skippii]

The pregen is slightly lighter and slightly more powerful than the newgen, so it definately can handle the track.
Vesrah brake pads up front make a world of difference. I was suprised, as I was told that an SS Braided line would be the better upgrade, but the Vesrah pad with the rubber hose is better than the steel line with the stock pad. MUCH better.

Exhaust: There's only about half a horsepower to be gained on the exhaust, BUT there's 26 pounds to be lost. On the track, that's HUGE.

Shock: Just about anything will be better than the stock rear shock. I put an RF600 on my 2006 250 and a ZX600 shock on my 2005 250, and mounted the remote reservoir behind the passenger peg. Adjustable damping is nice, but even some mattress springs from your bed would be a good upgrade from stock.

Tires: Here's where the new-gen has the advantage. The rear is simple: just mount a hypersport front tire backwards, since they're the only sticky rubber you'll get in 130-16. The front is a bit harder. MT75s work if you pay careful attention to tire pressure.

Forks: People say that Cartidge Emulators are the single best thing you can do to the Ninja 250. I haven't tried them myself. I've used both Eibach and Progressive springs.

I swapped the whole front end on my 2005 to one from a Ninja 500, so I got the stiffer forks and 17" rim.


At the very least, I'd go with Vesrah pads and a better shock off ebay, and increase the preload on the forks, and ditch the centerstand before it throws you off in a corner. Won't cost you more than $100 to get started.

[PlaneGuy]

Originally Posted by Alex

Yup - getting the system up to snuff (pads, fluid, line as needed) will optimize it, but the new-gen still has a larger disk and a slightly better quality caliper. When both versions are at the same level of care, the new-gen bike will still have somewhat better brakes.

Oh, no doubt. It is just that many don't realize how much one can improve the existing brakes by using a really good DOT4 fluid with a high wet-boiling-point, proper bleeding, and sport/race compound pads. Brake fluid is hygroscopic (absorbs moisture) and goes bad over time, and not a very long time at that. When you are on the track and getting the brakes hot, they will get spongy from the moisture boiling in the caliper even if they don't fade. Just remember, when it comes to brakes, you want to get it hard and keep it hard.

If you are a spec racer you might not have the option of changing to a brake with a larger rotor so you have to make do with what you have. Then the trick is to make it work as good as possible. Regardless, the front brake on these bikes should be able to lock up the front wheel or lift the back wheel under maximum-effort braking.

FWIW, I change brake fluid on my track car every six months no matter what and always use freshly-purchased fluid. It makes a difference. I suspect it is the same for bikes. (Sorry, my last race bike had drum brakes.)

[sombo]

Originally Posted by Racer x

I have an old kerker on my 88 . Area p just came out with one I think . There was also a muzzy .The problem with the 2 in to 1 for a pre gen is you have to remove the center stand.

Nope. Had the yoshimura 2-1 exhaust on mine and still had the center stand and now I have the area p version and still have the center stand.

[cerberusrex25]

Did you sell your yoshi? I am kinda looking for that one and is kinda rare.

[sombo]

Mine wasn't worth selling. The pipe was rusting and dented, and the can was also scratched and dented. I would honestly get the Area P setup. I like the sound of it better than my ancient yoshi. Of course I haven't run it much since the carbs still need some tuning so the bike stops acting up below 5k rpm. Oh and the reason the Yoshi is rare is because they stopped making the pipes and now only make slip-on cans.

[s2kenny]

Originally Posted by Skippii

The pregen is slightly lighter and slightly more powerful than the newgen, so it definately can handle the track.
Vesrah brake pads up front make a world of difference. I was suprised, as I was told that an SS Braided line would be the better upgrade, but the Vesrah pad with the rubber hose is better than the steel line with the stock pad. MUCH better.

Exhaust: There's only about half a horsepower to be gained on the exhaust, BUT there's 26 pounds to be lost. On the track, that's HUGE.

Shock: Just about anything will be better than the stock rear shock. I put an RF600 on my 2006 250 and a ZX600 shock on my 2005 250, and mounted the remote reservoir behind the passenger peg. Adjustable damping is nice, but even some mattress springs from your bed would be a good upgrade from stock.

Tires: Here's where the new-gen has the advantage. The rear is simple: just mount a hypersport front tire backwards, since they're the only sticky rubber you'll get in 130-16. The front is a bit harder. MT75s work if you pay careful attention to tire pressure.

Forks: People say that Cartidge Emulators are the single best thing you can do to the Ninja 250. I haven't tried them myself. I've used both Eibach and Progressive springs.

I swapped the whole front end on my 2005 to one from a Ninja 500, so I got the stiffer forks and 17" rim.


At the very least, I'd go with Vesrah pads and a better shock off ebay, and increase the preload on the forks, and ditch the centerstand before it throws you off in a corner. Won't cost you more than $100 to get started.

A lot of excellent information right there, I used to think that the pre-gen was limited in it's "upgrade-ability" but I guess you just have to try a little harder. I'm definitely going to check out some better pads such as the Versah's you mentioned. The shock swap also sounds like a great mod. With OEM shocks being so darn cheap on ebay the only issue I see is finding one that works without too much modification/custom bracketry.

Originally Posted by PlaneGuy

Oh, no doubt. It is just that many don't realize how much one can improve the existing brakes by using a really good DOT4 fluid with a high wet-boiling-point, proper bleeding, and sport/race compound pads. Brake fluid is hygroscopic (absorbs moisture) and goes bad over time, and not a very long time at that. When you are on the track and getting the brakes hot, they will get spongy from the moisture boiling in the caliper even if they don't fade. Just remember, when it comes to brakes, you want to get it hard and keep it hard.

If you are a spec racer you might not have the option of changing to a brake with a larger rotor so you have to make do with what you have. Then the trick is to make it work as good as possible. Regardless, the front brake on these bikes should be able to lock up the front wheel or lift the back wheel under maximum-effort braking.

FWIW, I change brake fluid on my track car every six months no matter what and always use freshly-purchased fluid. It makes a difference. I suspect it is the same for bikes. (Sorry, my last race bike had drum brakes.)

Good point there, I should be able to flip the thing right over if I tried hard enough. I was quite spoiled with 1 finger braking on the CBR. I'm going to try to throw on a few more fingers and get some fresh brake fluid.

[Skippii]

Originally Posted by s2kenny

With OEM shocks being so darn cheap on ebay the only issue I see is finding one that works without too much modification/custom bracketry.

I am a very firm believer in the idea that "You can make anything fit if you try hard enough."

It was my belief in this that caused me to buy an arc welder and oxy-acetylene torch, but it's also how I was able to install a dirt bike shock on a Ninja 500.

[Nemesis]

Wait, you plan on riding your GF's bike as a canyon carver/track bike? Mind if I ask how you crashed your current bike? LOL

[Skippii]

Originally Posted by Racer x

The pre gen bike has more power on top end also.

[PlaneGuy]

Nice dyno HP curve. You don't happen to have the torque curve too, do you? That is the more interesting one as it tells you what is going to happen at any particular RPM. When I dial the throttle on starting at, say, 4000 RPM, and hold it there until I hit redline, I feel a clear increase in torque starting around 8000 RPM and starting to trail off at around 12000 RPM. (Found that out yesterday when I went for my ride and had restored the stock air box.) It would be nice to see the dyno show how much is happening rather than just a seat-of-the-pants measurement.

(I may try it again using PocketDyno, a nice ap for the iPhone that uses the internal accelerometer to turn your car or bike into an inertial dynamometer.)

[sombo]

Originally Posted by PlaneGuy

Nice dyno HP curve. You don't happen to have the torque curve too, do you? That is the more interesting one as it tells you what is going to happen at any particular RPM. When I dial the throttle on starting at, say, 4000 RPM, and hold it there until I hit redline, I feel a clear increase in torque starting around 8000 RPM and starting to trail off at around 12000 RPM. (Found that out yesterday when I went for my ride and had restored the stock air box.) It would be nice to see the dyno show how much is happening rather than just a seat-of-the-pants measurement.

(I may try it again using PocketDyno, a nice ap for the iPhone that uses the internal accelerometer to turn your car or bike into an inertial dynamometer.)

Actually that's the HP you feel kicking it up in the higher revs, not the torque. The torque actually starts to die down in the upper revs because it's HP that gets you your top end speed while torque gets you your off the line acceleration. The max torque on the pre-gens hits around 9-10k and dies off fast after that, right about the time that the horsepower really starts kicking in.

[PlaneGuy]

Originally Posted by sombo

Actually that's the HP you feel kicking it up in the higher revs, not the torque. The torque actually starts to die down in the upper revs because it's HP that gets you your top end speed while torque gets you your off the line acceleration. The max torque on the pre-gens hits around 9-10k and dies off fast after that, right about the time that the horsepower really starts kicking in.

Torque is force. Force is acceleration (F = M*A). When you feel acceleration increase, that means torque is increasing. When you feel acceleration decrease that means torque is decreasing. So acceleration (in a given gear) always follows the torque curve.

HP is power or how fast work is being done done (work = energy). In this case it is torque (force) times RPM (distance). So the HP curve doesn't really tell you as much about how the bike will respond (accelerate) as the torque curve does. In fact, it doesn't really tell you anything at all. More on this below.

I suppose you can look at HP as being "top end speed" but if I were to actually sit down and calculate top-end-speed, it would be based on tire rotational losses, aerodynamic drag, mechanical friction losses in the drive train (assuming I only have the torque curve at the engine), gear ratios, and TORQUE. HP actually never enters into the calculation. In the end, top speed occurs when frictional losses (drag, etc.) equals available driving force (torque).

So, in one way you are right: if you want to go faster you do need to generate more HP. But it is the torque that we use to figure it out, not the HP number. HP just sort of tells us what happened, not what is GOING to happen. Torque tells us that.

Where HP gets interesting is if you want to compare available torque (force and acceleration) at the rear wheel for different RPMs and gears. You may be wanting to know where the optimum upshift point is for each gear. In that case I would use HP to compare torque at the rear wheel for different gear ratios and RPMs. It saves a step in calculation.

And I hope I haven't offended you. It is not my intention. This is what happens when you talk about this stuff with an engineer and a physics teacher. I tend to drop into teaching mode at the drop of a hat. I make my middle-school students use this stuff to figure out how fast their robots will go and how steep a hill they can climb and we always end up using the torque numbers, not HP.

[Skippii]

I completely disagree with both of you guys. Just look at the graph for HP, work out the torque using hp=torqueXrpm/5252, and then use newton second law, F=MA, (taking into account the lighter weight of the older bikes) to figure out everything you need to know about the bikes power. Or can't you do that in your head?

[Alex]

We've had that discussion a few times here as well. It's always fun.

What is Torque and Horsepower?

[Skippii]

Oh...that was a joke, by the way. My point is just that torque and horsepower are really two ways of showing the same data. If you know the RPM, you can easy convert between the two. They're not two totally separate things.

[PlaneGuy]

All roads lead to Mecca. (Or is it Rome?)

One can move freely between HP and torque as long as one knows the RPM. But to calculate acceleration, you only need the torque number. The only time HP makes the calculation easier is when you want to compare acceleration in different gears at different RPM values.

So, you are right, it isn't worth arguing about. The only difference is how you choose to set up the problem.

But it is interesting to realize that torque is a measured value. HP is a calculated value and is calculated from torque (times RPM times constant).

No worries! It is all good!

[PlaneGuy]

Like I said Skippi, no worries. Hardly any blood on the screen here at all.

Bikes, cars, airplanes -- they are all ways to have fun playing with science!

[Skippii]

Originally Posted by PlaneGuy

So, you are right, it isn't worth arguing about. The only difference is how you choose to set up the problem.

Oh, I never said that! I love me a good argument!
I've gotta get to sleep now, but I'll be back for more later--because I do disagree with a small part of what you said.

I'm no physics teacher, but I did get the highest grade in the class in my 2nd year of physics in college...so even if everything I say is wrong, I have the vocabulary to make people think I know what I'm talking about!

[s2kenny]

Originally Posted by Nemesis

Wait, you plan on riding your GF's bike as a canyon carver/track bike? Mind if I ask how you crashed your current bike? LOL

I'm still going through the legal process.. but what I can tell you is that while I was up in some canyons, I went head-on with another motorcyclist!

Here's some pictures of the accident if you're interested http://mtpalomarphoto.com/picture.ph...iconNum='1'

[PlaneGuy]

Originally Posted by Skippii

Oh, I never said that! I love me a good argument!
I've gotta get to sleep now, but I'll be back for more later--because I do disagree with a small part of what you said.

No problem. If I have made a mistake then I want to set it right. I hate to have wrong information stay out on a forum where someone might use it mistakenly to their or someone else's detriment.

I'm no physics teacher, but I did get the highest grade in the class in my 2nd year of physics in college...so even if everything I say is wrong, I have the vocabulary to make people think I know what I'm talking about!

Absolutely! If you can dazzle 'em with brilliance, baffle 'em with bulls--t!

All kidding aside, we are talking about physics and thermodynamics. It isn't a matter of opinion, it is a matter of engineering. Sure we can approach the problem from different directions but, in the end, we are going to end up with the same answer.

[sombo]

Ok, look at the numbers. You said you feel it kicking in after 8k rpms. The torque DROPS at around that point in our bikes but the HP jumps up. So like I said, what you are feeling is not the torque, but the hp. You can't be feeling an increase in torque in rpm ranges where it's going down, that defies logic and physics. You should realize this being a physics teacher. You can't feel an increase in something when it's value is decreasing.

[Alex]

Mike - you're offbase here. We've had this discussion before, and I thought you got it last time.

Torque and horsepower aren't separate things. You can't feel one and not the other. The rider feels the engine pushing them along. The output of the engine can be expressed in torque or hp. HP is calculated along with the revs; torque is independent of the revs.

[PlaneGuy]

Hi Sombo. Alex, Skippii, and I are all correct. What you feel is torque, not HP. HP is just torque x RPM (x a constant but that doesn't matter for this calculation). HP is actually a calculated thing while both torque and RPM are the things that you measure AND feel.

Torque is a twisting force. You apply a twisting force (torque) to a thing that goes around (a wheel) and if that thing is in contact with the ground, it then applies a linear force (push) to the ground. Newton's third law then says that there is an equal and opposite force applied to the bike, which makes it move forward. So the forward motion of the bike comes from the backward force applied to the ground by virtue of the torque applied to the wheel.

If we increase the torque, we increase that backward linear force. If we increase the force, we increase the acceleration. If we decrease the torque, we decrease the linear force against the ground, and we have less acceleration. So acceleration of the bike is directly controlled by torque, not HP. If I feel more acceleration, the engine is producing more torque. If I feel less acceleration, the engine is producing less torque.

In a typical internal combustion engine, torque begins to decrease above a certain RPM. It has to. As RPM increases there is less time to get a fuel-air charge into the cylinder and so there is less fuel to burn and produce heat. Also, the combustion process takes time and at higher RPMs there is less time for the combustion to complete and cause the gasses to expand, thereby applying force to the top of the piston. Less force on the top of the piston means less force applied to the crank through the connecting rod, and less twisting force (torque) coming out the crankshaft output.

But when this happens, even though torque is decreasing, RPM is still increasing. If RPM increases at a rate greater than the rate at which torque is decreasing, horsepower continues to rise. At some point the torque is falling off as fast as the RPM is rising. This is what produces the flat-topped HP curve we normally see.

Hopefully this helps you visualize the process.