It’s funny you should mention that because I have a spare 110 esp engine (a Vision Mk2 engine) in the garage from my previous scooter that was written off and I pulled the air filter box apart last night. It does have a steel insert on one side of the filter. Which I guess would restrict airflow but I don’t know by how much. Surely all those holes in the filter equates to more that the inlet hose down to the throttle body?
Please anyone correct me if you think I am wrong:
Throttle body opening is 22mm wide
The pipe leading from the air box to throttle body is 25 mm wide so no restriction there if I go up to 24 mm throttle body.
The bit I don’t know is how much restriction the air filter would have on air pressure into the engine. When you consider an engine running at 5000 rpm is taking in air 2500 times a minute or 41 times a second? When you look at it that way the air box is emptying many times a second (does that sound right?).
I’m guessing it’s restricting somehow but I’m not too concerned about this as I’m only increasing the potential air flow by a little. I know some tuners of the MSX use 31mm or even 35mm throttle bodies so the increase needed in airflow would be quite significant. Maybe not so in my case by just enriching the mixture a little with a little more air. I’m wondering and I suspect these scooters run quite a lean mixture as standard and there’s potential for more power by just adding more fuel assuming the O2 sensor and fuelling map in the ecu doesn’t restrict that too much.
Your thoughts and expertise on this anyone would be very much appreciated.