My Honda NSR125

In May '99 I bought a brand new Honda NSR125. Since the bike happened to be restricted to a meager 15 hp, I simply had to purchase a new Gianelli exhaust system the following day. Delivered 22 hp at the rear wheel and was believed to be capable of 160 km/h sitting up right, have done 120 in fourth gear though (must admit I haven't tried it properly...).

With only the Gianelli exhaust fitted, the engine slowly begins pulling at 3500 rpm, between 4500 and 5000 rpm it can easily keep a comfortable pace within any speed limit, except the motorway where you need more revs to keep up with traffic. At 8000 revs the bike suddenly flies off all the way to redline at 11000 rpm, this is where the "put-put-put" sound turns into a noisy scream (which people do hear!) combined with a massive vibration, almost makes you feel the whole bike's falling apart.

Accelerating from standstill to 100 km/h certainly doesn't set the world alight when taking close to 11 seconds to hit 4th gear and 100km/h (14 sec. with 15hp). But hey, it sure does make it a whole lot more fun to drive!

Once I'd run it in, I ordered a new cylinder! A 185cc Eurocilinder to be exact, but it didn't fit because it doesn't fit with the new electronics and driving without those it overheats... Then I got hold of the unrestricted Italian version of the cylinder with 28 hp, unfortunately it turned out to be so expensive we sent it back. Bad luck seems to be my worst nightmare I found out recently, the brand new Malossi 180cc cylinder was after 5 long months of waiting obviously not ready (March 2000). This meant at least 1 more month without a bike to ride...Don't even try to imagine what became 8 months without your pride, it simply can't be explained in words!

Have now got hold of the Polini 160cc alternative which has been fitted along with a new ignition system and an exhaust level adjuster from the unrestricted Italian version of the bike. The latter is a must if you have a restricted bike and plan to increase the displacement. If it's not done, the cylinder will most likely overheat and come to a permanent halt. The amount of horsepower developed with all this fitted is 34,3 hp with a similar power band like when only the Gianelli exhaust was fitted. I'll have it tested on a dyno to get an accurate result sometime this summer.
Top speed is said to be close to 200km/h! (187 km/h), but it only runs 10km/h faster in 2nd gear so I expect it to do somewhere close to 170 km/h on the speedomeeter. Up my favourite straight it runs 20 km/h faster (130 km/h) uphill without any sign of struggle. Downhill seems to be the same speed increase (150 km/h), except I haven't quite had the balls to try it out yet.
The NSR hits 100 km/h in 7.3 sec. with the Polini cylinder, the un-restricted NSR (28hp) uses 8.4 seconds.
Bye bye GTi's!

For those of you interested in fitting the Polini Cylinder you ought to know that the piston seized at 550 driven kilometers with full throttle at 10000rpm. That was very depressing, but we believe to have fixed the problem by fitting a 150 jet rather than a 135. Now it runs without any problems except it happens to freeze at 7500rpm as if it's cold. A 145 jet will be fitted very soon to cure that minor problem.
Except for the jetting problem the NSR easily copes with the pace of a 34hp Suzuki GS400 with a performance exhaust and the Aprilia RS125 of a friend of mine is usually left in a cloud of smelly blue smoke. Which is great! The NSR has finally turned into a real pocket racer and lisence killer which makes it a whole lot more fun to drive. Yes, fun ought to be the right word, but very expensive...

People say I'm waisting my cash when I tell them I've increased the NSR's wheels width with 1 cm at the front and 2 cm at the back, but I prefer to focus on the improvements rather than the downside of all this. Doing this resulted in far greater grip when finally being able to fit some decent rubber. I've heard Dunlop 207GP work great when fitted on a RS250 with twice the amount of horsepower, but the final decision ended up being Dunlop SportMax (D207) and SportMax Touring (D205) at the back, dimensions are 150/70 and 110/70. Stability is increased by bucket loads and grip is great too, unfortunately the tires are mismatched which means the bike never can be pushed down to extreme lean angles. Nevermind if you intend to use the NSR for touring, but as we all know, lean angles is half the fun... Now where can I get a cheap pair of Dunlop D207GP's....?



Misson accomplished!

Roll on next project.... CBR600

Any questions? Mail me!