Bill Cudney of Cudney Racing in Ontario reports the installation of TPI Low Boys into the new MX Z 800 REV airbox provides an increase of up to five horsepower. They run with the valves open down to about 10 F, close one off at that temp, and close off both valves at 20 F. Cudney has integrated the Low Boy valves into several of their power-up packages, with impressive power gains using stock cylinders and exhaust system in a package includes V-Force 3 reed cages, reed spacers, a head kit, and TPI Low Boy valves.
We’ve also heard from some mountain riders who have been adding the Low Boy valves to the RX-1 Mountain intake to provide added airflow when the stock intake starts to become restricted with snow. Donnie Williamson of Wild Horse Distributing has developed a kit that blocks off the OEM intake (that is really tough to get at when it becomes restricted with powder snow), modifies the airbox (if you can call it that), and installs five TPI Low Boys on the cover. Williamson says this provides an increase in airflow, requiring larger main jets and some other tweaks to compensate, with the result being an engine that is way more responsive.
Jeff Meidinger at Dakota Performance has also seen excellent results using the Low Boys on the new 900 twins and F7 Firecats, integrating the TPI Low Boys into his power-up performance packages for many models.
We’ve even found the Low Boy valves to work extremely well on four-stroke dirt bikes; we installed one into the airbox on a four stroke Honda Enduro bike and immediately realized more power, easier starting, more tractability, and less stalling. The possibilities are endless!
Ask for the Low Boy valves at your favorite speed shop or contact Thunder Products directly at 320-597-2700. They present an attractive option to permanent airbox modifications and provide the tuner with yet another option in increasing the airflow characteristics of the engine.
The TPI Low Boy adjustable intake valves work well on snowmobiles, ATVs and dirt bikes. They allow additional airflow through otherwise restrictive airboxes, and can be opened or closed.