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Discussion Starter #1
Hi guys,

I'm from Portugal, in 2008 I've imported an Honda CBR 250RR MC22 1991' model from Japan, this is the only bike here in the country since this model was never legalized / comercialized before.

Yesterday, I've decided to get her into a dyno, the temperature was around 30º (hot), no wind fan on the dyno.


The values were:

47.1 crank HP @ 16 480 rpm
43.2 rear wheel HP @ 16 480 rpm
13.1 Nm @ 12 900rpm


The CBR only has a Yoshimura R-55 Slip&On without dbKiller and it was rejeted.
 

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the dyno run should be done in 6th as it has the closest ratio to 1:1
 
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boingk said:
Impressive power figures, but the torque seems way down. It wasn't being measured in ft/lb was it?

- boingk
Just looking at my dyno figure and you are right. It is down on torque.

My dyno was 43.41 HP and 22.51 Nm.

My bike is down from the better dyno at 47 HP and I can't even remember the Nm, but 25/7 rings a bell.

I think I've snapped a piston ring in mine.
 

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I think I've snapped a piston ring in mine.
Ouch. Hope its nothing too serious. Be interesting to get my bike on the dyno and see what shes putting out. Of course, that'd only be as a starting point before fitting a decent silencer and rejetting to suit...plus some good 100% synthetic 10W-30 in the sump haha.

- boingk
 

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Discussion Starter #8
Hi guys,

Yes, the torque figures ( Nm ) are really strange and low, Honda declares 23.5Nm @ 12 000rpm and 13.1 Nm is pretty low.

But, on the road, the bike response is very very good since 4 000rpm, so maybe it was a dyno misreading for the torque since the power figures seems ok ..
There was a first dyno pull which achieved 53.2 hp, but then the operator noticed that the bike was slightly wrong positioned on the roll.

Then the final pulls done are in the video with the correct values.

From what my mechanic said (we made the revision 1 year ago), is that the engine is very detuned in standard form, in terms of head, air filter, carburation, ports etc ..
But I want to maintain the bike as stock as possible ( a part from the slip&on )

Did anyone compared his CBR 250RR with another bikes ?
Like Supermoto, 2-Stroke sport bikes etc .. ?

I ask this, because I possess another bikes, like Aprilia RS 250, Yamaha RD 500 V4, but my Aprilia is already modded and it is superior to the CBR 250, but 2 years ago I've made a Trackday with the CBR 250 and I could keep up with a guy on a standard RGV 250, even in acceleration and top speed (+190 kmh)..

I have Husaberg FS 650 SM and a KTM 520 EXC SM, and the CBR can keep up in acceleration with the KTM 520 !!

I wanted to compare with a 100% stock Yamaha TZR 250 (45 - 50 hp model), because I believe the CBR 250 is similar or even slightly superior in acceleration till 190 kmh
 

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Aprilia RS125 was my first bike, and it was slightly physically larger and a lot more flickable than the Honda. Rear suspension was shot, but even with that I feel it was quicker to respond. The front Brembo caliper gave good feel too. Riding position more sports oriented and engine quoted at 30hp @10,500rpm.

I would say it was close to the CBR250 due simply to having awesome handling, even though it was down on power. I would only imagine that a stock RS250 would blow a CBR250 out of the water.

Cheers -boingk

EDIT: Remember that depending on the model of RGV, they may only have around 40hp. Using better expansion pipes & rejetting will increase this towards 60hp and the CBR won't stand a chance. Check out the dyno graphs at tygaperformance.com for a bit more info.
 
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BroLy, you have a very impressive collection of motor bikes. I'll keep that in mind if I ever visit Portugal again. Are you from the main land or the islands?
 

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Discussion Starter #11
studricho said:
BroLy, you have a very impressive collection of motor bikes. I'll keep that in mind if I ever visit Portugal again. Are you from the main land or the islands?
Hi studricho,

I'm from Lisbon, the capital of Portugal ! If you ever visit Portugal tell me.

About the performance, I don't doubt that plenty of bikes out there are way better than the CBR 250RR on track / corners, I also believe that the suspension and brakes of the Babyblade are it's handicap.

But when I was talking about comparisons, was in terms of straight line acceleration / top speed.

I also have an Aprilia RS 250 2003' with plenty of mods (specific hand-made exhausts, modified air filter, new gigleur kit, electronics, PVM wheels, carbons etc etc etc) and it is faster than the CBR, but that's obvious since the RS 250 has actually +60 rwhp .. against the 43 rwhp of the CBR ..
 

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in terms of straight line acceleration / top speed.
It depends on what bikes you're looking at.

The stock 250 two-strokes should be good for around 50 to 60 crank hosepower, and in typical stroker style it comes all at once. I have no doubt that they'd be faster than the CBR250. Top speed for a stock RS250 is around 210km/h if I recall correctly, with acceleration being better as well.

If it helps, a Suzuki DR-Z400 motard is very torquey down low in the rev range and delivers a peak of around 40hp. It is quite quick off the mark, and very light, but doesn't have a good top speed (~150km/h) to due low gearing and an engine tuned for low to mid range torque. I used to ride one.

I also have an '85 GS850; a big, lazy 4cyl air-cooled shaft drive. It is brutally quick with some mods (individual 'pod' filters, 4-1 exhaust, rejetted carbies) and will definitely beat the 250 even though its around 260kg fully fuelled. Top speed was about 210 to 220km/h when new.

Another bike I have ridden was a BMW R1100S. It was very quick off the mark, and would wind up to 220km/h. Comfortable tourer, as is the GS850. As I said before, it all depends on the type of bike you are looking at.

- boingk
 
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