Yamaha WR250R Airbox Flapper Intake Mod

[@danielwimberly7806]

Thanks for the video, just got a wr250r and I plan on doing the flapper mod. I just wanted to share my thoughts on the foam you stuffed in the air box port. I would imagine it defeated the purpose of the flapper mod on higher rpm. Just my opinion

[@joelwallisadv]

Nice, congrats on a sweet bike. It could but I don’t think enough to notice. It’s not super dense or thick. Just enough to help with dust.

[@Jerry-lt2jo]

I'm in agreement here. You actually have less airflow at WOT than with the stock set up.

[@michaelglenn2468]

Just install a pre filter over the opening. A big wad of foam jammed in there will be too restrictive.

[@TheStewy09]

having a dirty airbox isn't a problem as long as the dirt stays on the outside of the filter no problem

[@k0d0kan]

Curious as to why you used the foam. Seems to me that will restrict air flow. When the flapping device is installed and it opens the air way, there is no filter stopping the flow, correct? AND, you have the air filter installed on the inside. What am I missing...? Something, I'm sure.

[@joelwallisadv]

The foam was used to help collect dust as we noticed the air filter got dirtier quicker since the flap is wide open at all times. The foam that was installed does not restrict air flow so no issues there.

[@lomparti]

@@joelwallisadv I bet it does restrict air flow the way you stuffed such a big piece of foam in there. I would cut it in half and just put it in there loosely. That would be more than sufficient to block 95% of dirt but also not restrict the air flow.

[@antharding]

@@lomparti It will defintely restrict airflow. He's basically added a second air filter. Put that piece of foam over your mouth and see how much harder it is to breathe.

[@alexandergotz5568]

The flap only closes when you let off the gas. The problem is that the flap slows down rapid gas changes. You also have to close the hole from the vacuum valve on the intake port, which causes turbulences. There is also a flapper in the exhaust that closes at 50kmh

[@bendayho]

I am curious why people even remove the vacuum valve. Why not just disconnect the hose. The valve is spring loaded and will keep the flapper down...no?