[subxero]

Originally Posted by Ninjinsky

Okay,
This is down to differences between early and late pregens.
The first UK and oz bikes were 40 hp (39.4)
The US bikes were 37
There have, over time been a whole raft of carb and timing changes to these engines as detailed in the wikipedia pagehttp://en.wikipedia.org/wiki/Kawasaki_Ninja_250R

The 40 hp engines had large carbs and were peaky developing less mid range and torque than the 37 hp.
The UK bikes are sluggish unless you keep them above 8000 when the "scalded cat" thing happens Hence our opinion that they feel "2strokey" to ride.
The US and later UK revisions developed less peak but more tractability.

Hope that Clarifies the issue for you, ( and 45 must be a misprint in the test article)

ps The early CB 750 went the same route with an initial 67hp dropping to 63hp once the model was established.As a racer the GPX didn't stand a snowballs chance against the Suziki's exquisite 60-70 hp RGVs and Yamahas of the day but its durability as a workaday bike is excellent by comparison

PPS What do you guys successfully Race Ninjettes against, It can't be 2 strokes.

just FYI wiki does not serve as an acceptable reference. Find me a handful of legit dyno's then we can talk.

Again, why can't tuners today hit these numbers with stock bore and stroke if it is simply carb/intake/exhaust mods + some timing? Why can't a 40hp engine go over 97mph? but it does a 1/4mile in 13 odd seconds and hits over 80mph in that quarter? There is a lot of conflicting info that just doesn't add up but I wouldn't expect anything less with info that is pulled off of wiki

as far as cb750 dropping 4hp ~ 6% I hardly consider that comparable to a 250 dropping >10hp ~ 25%

not sure about your "what do guys successfully race ninjettes against?" question Ninjettes race against other ninjettes in stock classes. People mainly seem to race the stock new gens. But I can't imagine rules could prohibit you from racing a stock old gen from 1987 which somehow has a >25% increase in hp but for some reason people don't race them in stock 250 classes? Clearly in stock 250 classes 2 stroke 250's are no allowed for obvious reasons. Similar to Motocross. The 125's 2strokes get paired with the 250 4's and the 250 2's get paired with the 450 4's But unfortunately it seems in sportbike racing a lot of places don't let 125 2strokes even race against the 250 4strokes, they are forced into other classes