TWIN AIR Power Cover/Power Flow Kit review

Twin Air is air filters. If you grab a random person at the track and ask them to name an air filter brand, I’d bet my house that they would say Twin Air. Back in 1972, they developed the first oil- soaked air filter that allowed air to flow through it, without allowing dirt, grime, and sand into the carburetor. This new innovative, reusable design would change the air filter game forever.

Over 50 years on Twin Air are OEM specified to more than 30 motorcycle companies worldwide. As well as having a whole range of filter care products and performance-enhancing kits.

In 2024 Twin Air released a new “Power Cover” for the YZ450F/YZ250F, to pair with their already successful “Powerflow kit”.

With the Powerflow kit and Power cover you receive: retardent air filter

1xTwin Air, pre-oiled, flame
1xAluminium filter cage
1xFilter cage bracket
1xPower Cover

To simplify things, the Power Cover is an alternative Air Box cover to replace the standard OEM cover. The differences are that is has more holes strategically placed to allow maximum airflow, without running a high risk of an overly dirty filter. It also has more volume compared to the standard OEM filter cover.

For those thinking what does this mean? Basically, the more air you can get flowing through the airbox into the engine the more power it creates. However, there is a fine line between letting air in and letting mud/grime in. If you just cover your airbox in holes, you’ll create more horsepower but your filter will be toast after a lap, and then you’ll be sucking all sorts of things besides air down into your motor.

The Powerflow kit also helps create more airflow as well as protecting the engine. The aluminium filter cage, unlike the standard cage, has no mesh. The aim of the mesh is to stop filters from catching a light as a result of a backfire. However, due to Twin Airs flame retardant filters, they do not need to use the mesh. The mesh may not seem restricting but in fact, sucks quite a lot of power.

Another benefit to the Powerflow kit is that the extra bracket pulls the filter down, creating a tighter seal on the filter box. Therefore reducing the risk of mud/grime being sucked under the filter. The standard Yamaha filter cage is held down by a slot at the back and a rubber tab that pulls over. This works well to begin with but over time the rubber stretches and your seal becomes compromised. With the Twin Air cage, you will not have this issue.

Now for the bit you came for. The Power Cover, coupled with the Powerflow kit will give you an increase of 0.9 horsepower. Now, that may not seem like a lot but in a sport that’s won and lost by a few seconds, it can make all the difference.

Not only do you see an increase in horsepower, but you also see an increased throttle body response. I’ve always believed that 75% of the race is from that gate drop to the first turn. It’s the only place you can pass 39 other riders at once. The increased throttle response will give you a better chance at being at the top end of the field heading down the start straight.

I found both kits super easy to install and user-friendly. I had concerns that on the YZ450F the increased throttle response would make the bike erratic and difficult to control in the low end of the power. This wasn’t the case, however. It still had the same smooth power, but the time from twisting the throttle to feeling it pull was lessened.

I do believe that the Powerflow kit is a must-have for both the YZ450F and YZ250F.If not for the power gains but for the longevity of your filter seal. The YZ450F is not lacking in horsepower but if you are a top pro rider you will benefit from the Power Cover. If you are like me and a weekend warrior, it is not a must-have in my book. However, if you are a YZ250F rider the more power the better. In a class where power is King, these 2 kits coupled together are a big must-have, and I can’t recommend them enough.

Tested and written by Brad Wheeler