Drilling airbox experiment

dariusjonsson said:

I removed the rubber elbow that goes into the airbox and dremeled out about a 4 square inch hole on the bottom piece of plastic between the battery and airbox. Butt dyno says it made a non-negligable difference. As you know, power falls flat on its face after 8k rpm and this seemed to help extend the torque curve a bit. Anyone have other mods to help it breathe better up top?

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It's really fun to play with engine improvements, and as Denno written to you, your improvement to be noticeable has to come with re-tuning the map in the ECM. I have been trying for a while to figure out how to get free maps for our CBR250R, and if there is a cheap (amateur) tool with which I can install the new map to our ECM. If you will know the subject, before me, then you are welcome to sharing us about it.

The guy in the attached video (Yamaha MT-7) "removed the rubber elbow that goes into the airbox":

Besides as Danno wrote to you our motorcycle comes out of the factory almost perfectly. Our motorcycle, which is sometimes defined as a motorcycle for beginners, is also a motorcycle that professionals know how to derive great pleasure from her. On the track with the right tires, your personal riding abilities at laps time may be no less noticeable than an extra few percent in power.
In any case the effort for improvement is certainly worthy and justified.
But it is usually better to switch to a motorcycle with a larger engine, instead of spending time and money on a motorcycle with a smaller engine.

The basic and cheap actions have already been done?:
1. New and improved plug.
2. New and improved air filter.
3. Change engine oil, to quality oil (fully synthetic).
4. Adjusting valves.
5. and cleaning of the fuel system, combustion chamber, and valve mounts with a substance such as BG-44K at a concentration close to 100%.

dariusjonsson said:

Anyone have other mods to help it breathe better up top?

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If you have accumulated many Km like me, over 66,000 km, probably a noticeable improvement will come with addressing the issue of the catalytic converter, which is probably at this point already quite blocked.
The options:

• Cutting the converter from the original muffler (frame work).
• Replacing the muffler.

B.C-Rob said:

they cut holes in the airbox and the bike ran significantly worse

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In our engine, the computer control unit can balance supercharged air intake (with certain limitations) by reducing the fuel injection times in the injector (mainly related to closing the control loop with the oxygen sensor). The old engines, without "smart" controls, even a change in altitude of over 1000 meters required a mechanical change in the carburetor nozzle. To balance the supercharged air intake they had to reduce the nozzle hole. Tuning engines to improve performance requires additional specialization over the knowledge of "normal" motorcycle mechanics.