To be fair an NSR should be able to take full throttle from 3k. On the dyno we test them from 4k upwards but they do take it well.
If it wont have a look at the reeds as well as the jetting. Alot of these bikes are 20 years old and have never had a new set of reed valves in their lives.
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If I have to take the carbs off once more...