I have a question that I hope all you NSR guru's can answer. I have a 92 NSR250 SE I have fitted TYGA pipes, moded air-box and performed a wire-splice. I just did a top-end rebuild on the motor. When I'm warming up the bike, I blip the throttle to about 6-7000 RPM and I would hear 2 distinct popping sounds from my exhaust. What does that mean??????

Hey Guest, any chance of a name?

Did you rejet when you fitted all that gear? If not you'll be heading for a siezure when you wind it on...

As for the popping noises, I'm not sure what you mean. Are they a continuous noise, or just a one off event at those revs?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I did not jett yet becuase the bike is not ready for the street yet, I just start up the bike in my garage. As for the popping sound, I only happens when I blip the throotle and release. You would hear a POP, POP from both exhuast cans.

Ah. Well I would suggest you rejet anyway, as the engine will be running lean and hotter than it should.

This may be the cause, as if the engine is running hot enough it will pre-ignite the mixture. To be honest though, I would expect you to notice the heat. Have you had the plugs out to check the colour since you ran it?

The most likely cause is an air leak in th exhaust system. Check that the exhaust headers are properly seated and sealed at the cylinder heads. I imagine the noise happens just as you throttle off, in which case the system is sucking in air from somewhere.

Have a look and let us know how you get on...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball