Sure you're not thinking of a derestricted NSR250?Originally Posted by imdying
Oh yeah, and the NS250R will wheelie off the throttle which the CBR250 won't do
Weekend cruiser
Sure you're not thinking of a derestricted NSR250?Oh yeah, and the NS250R will wheelie off the throttle which the CBR250 won't do
Forum whore
Naw, the good ole NS250R, one pipe up around your butt. Gas it to 6-1/2, back off, rip the throttle back on, she'll wheelie quite happily
You've had some back luck by the sounds of it. I managed 15000kms in 6 months without having anything blow up! (although I did snap an extremely abused chain)
Are pistons not available, or you just won't pay Honda $300 each for new ones? Have you talked to someone like HPE about the barrels? Perhaps having them cast iron sleeved? No idea if anyone in NZ can renicasil a bore, but someone here will know.
You can't blame the bike for blowing a replacement piston inside of 1000kms. That's entirely the fault of the person who fitted it (well, unless you thrashed it straight away). I think you'd find that a properly rebuilt top end would last you a significant number of kilometres.
Heaps of my mates did the rebuild with old pistons and barreks on NSs, NSRs, RGVS and RZs when we were younger and all kicking about on 250s... that was the first time I ever saw sparks (bits of ring) fly out of an exhaust (98 NSR)If you want to be able to ride more than 20kms from home without problems, you'll need to rebuild it properly, which is expensive yes.
Forum whore
Don't be suckered by the false God of HP matey.
87 CBR250 has a pathetic 25.4Nm of torque
86 NS250R has a relatively healthy 36.3Nm of torque
Over 40% more torque ensures that NS will rape the CBR quite convincingly. The torque curve is also fatter and healthier on the stroker
Hardcore Biker
Power, is proportional to torque times revs. Power is what's important for going fast. The CBR get's good torque up around 15,000rpm which means that it gets good power. The twostroke probably maxes out around 11,000rpm, which means that even if it does have more torque, the CBR still has a better multiplying factor on that torque. Power is what matters to me. The CBR250 is still quite a fast and fun bike. If you want someone to explain why they will be keeping their 250 fourstroke after they get a bigger bike, then talk to N4CR. They are a fast bike, not as fast as the 2strokes, but in the right hands they can keep up with most riders on 600's and 1litres through the twisties. I think I could beat 90% riders around a track with me on my CBR250, and them on an RGV250, or an NSR250.
Forum whore
Somewhat agree about the keeping 250 thing, but there's a couple mitigating factors in favour of the NS; he has it, it's a two stroke, it's faster than the CBR, the CBR is in Auckland; the CBR is an unknown quantity.
Torque isn't just proportinal to torque * rpm, it is torque * rpm (/5252). Power is important for maintaining speed, but torque is what gets you there. Compared to the NS, the CBR has little torque, and it's peaking out at 10,500rpm (and well petered out by 15000rpm). The NS makes peak torque at 8500rpm (and 40% more of it), and has a solid curve underneath that.
The multiplying factor doesn't actually matter because, as you've shown, it only relates to the amount of hp produced, and they both produce the same. As the NS has to build up less revs, it means you can get into the next gear sooner, keeping it in the sweet spot, where as the relatively low torque CBR has to drag itself across a broader (but lower) spread of torque. Even if you were short shifting the NS.
Whether you could be beat 90% of riders around a track on the CBR vs 2 stroke is irrelevant. With very few miles to familiarise yourself, you could beat you around the track on the NS vs CBR, and that's what matters.
However, regardless of whether it's a better/faster bike (they're very similar, except for the motors, the NS riding position is a little less armchair, a little more over the wrists), it just seems to me that $2300 + petrol + ferry would go a long way to sorting the NSs motor out, rather than buying an unknown CBR which is 1400km and two days ride away.
On that note, does the NS have a nicasil plated bore, I pretty sure it's a cast iron one (which means you can bore it). I wonder if a 0.5mm oversize piston is available from either TonyB or Honda themselves?
Hardcore Biker
Just getting into semantics here, but power is proportional to torque times revs. the word 'proportional' allows for a proportionality factor, or a multiple, in this case you have said that it's /5252, so neither of us are wrong. Otherwise I would have said Power is equal to Torque times RPM.
I think you misunderstand how horsepower works. The smoother HP curve with a larger percentage of the rev range providing good power, is more useful power. Lets say a toyota Corolla puts out 100Hp at about 5,000rpm, and a 600cc motorbike puts out 100Hp at 13,000rpm. Both these vehicles will be putting out the same power at the wheels (assuming drivetrain losses are the same) even though the corolla will have to be geared higher to deliver that power at the same speed, if they were both the same weight (even though we all know the corolla is a lot heavier) they would both accelerate at exactly the same rate if they were both putting out 100Hp, even though the Corolla had to be geared higher to put at that power at that speed.
Torque is merely twisting force, Power is what makes you go fast. 45Hp is 45Hp whether you are putting it out at 10,000rpm or at 15,000rpm. If both of these bikes weighed the same, and were both at max power, for that instant they would both accelerate at the same rate. Now, due to the fact that the CBR has an extremely smooth power curve, that would mean that it can more easily be made to stay very close to it's max power figure, whereas the much peakier two stroke will drop considerably from that figure when you change gears. Thus it is more likely that you will keep very close to 45 HP all the time when you are racing the CBR. This of course doesn't take into account the fact that the NS250R is lighter, or that the NSR's and RGV's are lighter and noticeably more powerful. But is rather just an insight into the workings of HP.
Torque is equivalent to force
Work done (Joules) = force x distance (or) torque x revolutions (with a multiplying factor)
HP (Joules/Second) = Work done / Time (seconds)
The more work you can do per second is the amount of power that you put out. The longer you can keep the power level up the more work you will get done in the same amount of time.
I'm sticking to my idea that power is what matters in this case, yes I realise that the torque drops off after 15,000rpm, but it's a gradual loss, just as it is a gradual climb on the increase in revs below 15,000rpm. But the bike will be putting out quite close to it's max power all the way from 12,000rpm right through to 18,000rpm. That's 1/3 of the rev range to play with. Much more than you would get out of the 2stroke. You generally get about 1/4 or less of the rev range close to max power on the 2 strokes.
My point about saying that I could beat at least 90% of riders on 2 strokes around the track on my CBR was really just pointing out that they are not that much slower than the 2 strokes, and in fact the most important difference between the bikes is the rider. And if you couple that with the cost effectiveness and relative worrylessness of the fourstroke bikes, makes them in my opinion the better choice.
I think what you are saying about the NS250R having to go through less revs to get to the next gear change could have some minor impact, in the stored rotational momentum within the engine, but seeing as the engine parts inside the CBR are pretty small and light, and the fact that when you change gears your bike pulls the revs down, effectively converting that energy into the forward kinetic energy of the motorcycle. The fact that you can leave the CBR in the same gear for much longer than the 2strokes is actually an advantage (as long as you keep it close to the max power of the bike), as you do not have to change gears as much.
The only reasons why I could see the NS250R doing power wheelies if it does indeed have only 45Hp, would be that:
a: The suspension isn't up to much
b: The weight distribution isn't too flash
c: If it were much lighter than the CBR
Or any combination of the above. Hell my very quick RGV250 didn't even do powerwheelies. Or maybe you are changing the weight distrbution by giving a yank on the bars just as you approach max power, could be done.
P.S. I've owned a very fast RGV250 Race replica that had been set up for racing (I only used it on the road though) for two years, so I'm also speaking from experience when comparing the bikes. Give me the CBR over the RGV any day (not for outright racing though, although I wouldn't want to pay costs on racing twostroke 250). I know a guy who spends $5,000 a season keeping his RGV250 racebike running well.
Forum whore
Regardless of the semantics, and I agree, in the real world they're as much just that, that 40% extra torque still matters.
It's the amount of torque available at any given speed that limits the vehicles ability to accelerate. The more torque you have at any given speed, the higher your acceleration potential is.
The CBR pretty much has over 80% of its torque available at any revs, which is why it's more theoretically more flexible.
The NS on the other hand only has 80% of its torque available through 40% of its rev range, which means more dancing on the gearbox. It's worth noting however, that is has the same torque available as the CBRs 80% from about 3000rpm, so it is somewhat a moot point. It's also has more torque available from 6000rpm than the CBR ever has. It's also worth noting that both of these bikes require dancing on the box if you're getting the best from them, and if you're not getting the best from them, then well the whole discussion is irrelevant
Forum whore
mate you could beat 90% of riders on gsxr1000's....
Muhammad AliOnly a man who knows what it is like to be defeated can reach down to the bottom of his soul and come up with the extra ounce of power it takes to win when the match is even.
.
YES
an NSR will kill a CBR on a track, ive seen them go up against and beat, Ducati999's, R1's and GSX-R 1000''s
it all depends on the rider, i guarantee you would get better lap times riding an NSR than your CBR
also another factor.
they may be the the same HP, but because the NSR is lighter its power to weight ratio would be better than the CBR.
also as the NSR was designed as a GP bike for the road. and is designed around an RS250 frame, the engineering is slightly better and is a lot more manoverable than the cbr so would hold a higher speed in the corners. also because it has a lower rev range it would hit its peak earlier making able to accelerate out of a corner quicker.
im not biased as i have driven both, i own 2 NSR's and buying a CBR250RR shortly
Forum whore
Simply fun bikes and you don't always have to loose your liscence on them (although it's easy enough..). Pretty solid too (the CBR in particular then zxr) and crash well. To be fast/keep up with squids etc you HAVE to learn how to corner like mad brake late and push your luck, makes you a better rider in the end. But that's the fun for me. Well not so much lately but I just ain't been riding as much though...
As with 2 strokes 250s being much quicker in a line... well, not a whole lot actually, have gone against a few and they don't do a whole lot more top end wise - 20ish or so km top speed more ain't a massive big difference really, they do flick in a bit quicker due to design and being 10-15kg lighter. I'd really like to see one in action though properly. Outta the power band they are toast though
edit: yeah they'd kill 'em around a track though.. but the 4's could keep running day in day out with just oil changes every 5-6k :P
Hardcore Biker
Well, maybe you are in that 10%.
Oh yeah, and good post N4CR.
Weekend cruiser
anyway any tips on cbr issues?
Hardcore Biker
Ok, the issues that I have had are listed below. This is over a long period with several of them:
Hmm, I've only had the usual stuff like a clutch cable, a chain, brakepads. Oh yeah I seized the calipers because of mismanagement when changing the pads. Nothing really bad to point out about these bikes. They are definitely the pick when it comes to 250 fourstrokes. If you do all the maintenance there is no reason why you can't get over 100,000k's and possibly much more.
If you want problems that people have had... go to: www.cr-x.org/cbr250 and go to technical issues forum on that site.
YES
yeah when chaning pads dont pull on the lever as you can pop the pistons out of the calipers if there is no pads in them.
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