Parts

2025 Tomasin Racing T500 Engine Kit First Look

A plug-and-play 500 two-stroke conversion kit for the 2021–2024 and 2025 Honda CRF450R and CRF450RX.

Updated: February 8, 2025

Enrico Tomasin is back at it. The former engine specialist for Honda’s MXGP team has released the 2025 version of his company Tomasin Racing’s T500 Engine Kit. This iteration is designed to work with the 2025 Honda CRF450R and CRF450RX, both of which moved to a new platform—namely in the chassis department.

Owners of the latest two generations (2021–2024 and 2025) of Honda CRF450Rs and CRF450RXs who want to transform them into a 500cc two-stroke can do so with Tomasin Racing’s T500 Engine Kit.Tomasin Racing

The T500 Engine Kit turns the latest two generations (2021–2024 and 2025) of Honda CRF450Rs and CRF450RXs into a 500cc two-stroke. Tomasin Racing states that no changes are required for the big-bore smoker mill to fit in the CRF450R’s and CRF450RX’s aluminum twin-spar frame.

Kickstarting a 500cc two-stroke dirt bike to life can be a daunting task, but that’s not a concern with the T500 Engine Kit as it features electric start. Carburetor jetting isn’t a concern either as fuel injection is employed.Tomasin Racing

What’s included in the T500 Engine Kit? Engine cases, a crankshaft, connecting rod, cylinder, piston, cylinder head, reed valve, billet intake manifold, spark plug, spark plug cap, gaskets, exhaust manifold, pipe, silencer, dedicated ECU, an electric water pump, billet water pump cover, radiator hoses, titanium cylinder studs and screws, a 14-tooth countershaft sprocket, and head stays (aka top engine mounts). An added offering specific to the 2025 kit is a Twin Air air filter.

Enrico Tomasin, owner of Tomasin Racing, designed the T500 Engine Kit so that no modifications need to be made to the CRF450R’s and CRF450RX’s aluminum twin-spar frame for it to fit.Tomasin Racing

OEM components from a CRF450R or CRF450RX are required, specifically the starter motor, starter motor gears, stator, flywheel, primary gears, complete clutch assembly, shifter and gear lever, and ignition and right crankcase covers. The T500 Engine Kit can be purchased with or without a gearbox. If the latter option is chosen, buyers must supply a full gearbox from a CRF450R.

The T500 Engine Kit retains the use of some stock CRF450R powerplant components such as the gearbox, ignition cover, and right crankcase cover.Tomasin Racing

As far as pricing, the T500 Engine Kit without a gearbox costs 8,500 euros (which is equal to $8,981 at time of publication) and with gearbox retails for 10,500 euros ($10,903). The big-bore two-stroke mill must be assembled, and Tomasin offers that service for 490 euros ($509). Having it put in the bike by Tomasin costs an additional 300 euros ($312). Shipping is not included with any of these prices.

Cost of admission to turn your 2021–2025 Honda CRF450R or CRF450RX into a fire-breathing 500cc two-stroke starts at 8,500 euros, which equates to $8,981 at time of writing.Tomasin Racing

Learn more about this fascinating 500cc two-stroke conversion kit for 2021–2024 and 2025 Honda CRF450Rs and CRF450RXs by visiting tomasinracing.net.