Just got of of the phone to a mate. Part of the conversation went along the lines of:

Mate - "I was speaking to this guy the other day, he said that he had an NSR 250 that did 150Mph. One of the smart card one's from Japan".

Me - "All NSR's are Japanese market. And i find it hard to believe that his did 150Mph".

Mate - "Well that's what he said. He's an engineer so it was probably really tuned up with loads of Japanese markets bits".

Me - "From what i've read on the Net with minor tuning he's probably looked at up to 70 Bhp ish max. Even GP 250's only do around 160Mph ish, so i really can't see it".

Mate - "It's nothing to do with Bhp. It's not as if i've not ridden a bike". (he used to do motor-x)

Me - "So what is it all about then?".

Mate - "You could have a 500Bhp car that might only do 100Mph....it's all about gearing".

Me - "I'm not sure you could gear an NSR to do 150Mph. If you could i wouldn't fancy riding a highly tuned 2-stroke at 150Mph".

Mate - "Maybe it's an ex race bike, road registered".

Me - "Maybe he was talking out of his arse?".

Mate got a bit of a hump on, after a bit of backwards & forwards (and getting no where) I changed the conversation to something else.

The question is......can an NSR250 MC28 do 150Mph?

Please tell me no so that i win
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88 NSR250 R2J (work in progress!) & 05 Aprilia SL1000 Falco

Yes, with alot of work. Ask Mr Matt,

My '21 will pull 140mph without to much fuss and stock gearing for an F3 HRC box (15/36) is just a tad over 160mph.
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If I have to take the carbs off once more...

I'm sure a 125 can do 150mph given huge gearing and a good run up with a car blocking the airflow!

I'd imagine an NSR geared for 150mph would completely miss the point of a small two stroke engine...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

That's my thinking, i mean what's the chances of this guy having F3 bits?
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88 NSR250 R2J (work in progress!) & 05 Aprilia SL1000 Falco

Not very high... me, StephenRC45 and Matt@TYGA have got them all!!

Matt's been speed-trapped at over 150mph, but we are talking funny fuels, ram-air and all sorts. The MC21 was the pinnacle of F3 development - it was all over by the time the '28 came along really, although there were some fast ones out there.
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Andy.
NSR-WORLD.COM

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More like 150KPH i would think. Point out the KPH clocks used on NSR,s to you mate

my 21 only does a ton but its how it gets there

fenton wrote:my 21 only does a ton but its how it gets there

That is when you think Andy's 21 will do 85 mph in first .Dam those F3 gearboxes
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Harley Davidson is the worlds most efficient way to turn petrol into noise without the harmful side effect of horsepower.

slip streaming the car is cheeting it should have to do it on its own
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94 mc28 SE

Not sure if it's quite 85 Wayne, but it's pretty bloody tall, especially now I've gone smaller on the rear. The rest of the box is real close though - I think nothing of rolling off the throttle and banging it down 3 gears to keep it on song!!

Steve's was real bad! His was so tall that you'd struggle to get it into 6th, and when you did it was just plain scary!!

I reckon you need 70hp and to weigh much less than 90kg to get anywhere near a true 150mph on an NSR... that or a bloody long hill!!
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Andy.
NSR-WORLD.COM

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While we're on the subject anyone care to share the formula to figure top speed. We have a local track with a 3200' straight and last time I was there I could pull 16/40 to 12500rpm just before a handfull of brembos and three clicks of the gearbox. I'm a 180#ish rider on a 265#ish bike with 70ish HP and a MC21 gearbox in a MC28. As long as there are no long straights though 15/42 is my choice More fun!!!
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1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike

Modern 250gp bikes hit 170+mph at the fast tracks (Mugello or Shanghai) and that's down just a 1200m straight, I'm scared to think what one could do if it was geared for it and nailed it down a couple of miles of runway, way past 180mph surely?

jkolewski, not sure what your after but there's a gear ratio guide here on Jamie's site, it's all at 10,000rpm but you can work it out from there.
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Its more than just gearing: you actually have to have the power to overcome the resisting forces. The faster you go, the more power you will need exponentialy. For example: It only takes about 40 HP on a bike to 100 mph, but it takes more than three times that to do 200 mph.

A good example is a Porsche 914. Its geared to do about 145, but it can't reach full rpm in the top two gears. Top speed is 112 mph, or 110 mph with headlights on. 109 if you have dual mirrors. In fact, in heavy rain the car won't even pull high gear. But, it does get 35 mpg at 70 mph all day long.
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james
Its not how fast you go...Its how you go fast.
MC21 Rothmans
RS250
RC31
CRF250X
748R
Porsche (many)
http://members.rennlist.com/j911brick/rennlist3_002.htm

Top speeds are all good fun, but how often can you actually get there to make the tall gearing worthwhile?

My 28 went over 150mph but (as Andy points out) that was on funny fuel, ram air and many many hours in the workshop and on the dyno. It actually hit 243kmh which is 151mph. I didn't really care at the time because it was in a race and if I could have had another 1mph I wanted it. I was up against 3XV'x that were also pulling very close to the 150mph mark, but my NSR was the fastest BUT.....usual story.....last lap, last corner, I was leading and a backmarker swung across the track in the strangest cornering manouver ever seen and hit me, sending me head first over the tyre wall

For the NSR's I use on the street I'll usually gear them for about 125mph as this is plenty fast enough and gives great scope for power wheelies, which is what it's all about really. My latest 300 creation is geared for 133mph @ 12500rpm just for starters, so we'll see how it goes.

I'm currently running 15/40, but I think I will go back to 15/42 as the accelleration through the gears is more fun than the MPH gain at the top!

I can't remember the smaller numbers inside the 'box, but I think we worked out 15/40 would be towards the mid-130's. With 'over 65hp' it will pull the redline in 6th happily, even carrying my 90-and-a-bit kg's!

Anyone out there have a spare 14T for the front?!
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Andy.
NSR-WORLD.COM

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