Four-Stroke Engine

4-STROKE: Head Porting and Valve Seat Service

TBT Racing engine modifications improve low-end, top-end and just make the bike pull harder from idle to the rev limiter. We know more power is good, but creating rideable, reliable horsepower that you can make the most of is the key to faster lap times. That’s exactly what you’ll get from TBT Racing.

At our facilities we use state-of-the-art computer software along with a Dynojet dyno to unlock extra horsepower that is hidden in your bike’s engine. Before any engine package is sold it is track tested to ensure superior performance gains.

TBT Racing was one of the pioneering companies to do engine work on modern four-stroke motocross machines.

We started with James Povolny Jr. in 2002, and after watching him leave Tim Ferry’s factory YZ426 behind by four bike-lengths off the start of every outdoor national aboard his TBT Racing CRF450R (August 2002), we never looked back. We start by completely disassembling your head (or complete engine), and then we replace any worn or broken parts. We port and texture the intake tract for maximum throttle response and optimum fuel atomization. We finish by porting and polishing the exhaust to maximize exhaust flow.

Valve seats are cut on a Sunnen VGS-20 seat machine with a fixed center for absolute precision. They are finished with a Diamond Finisher for seat concentricity that is far superior to the Serdi or Neway hand cutters used by other companies. This ensures superior valve seal and valve-train life. Single-piece Ti valves, performance cams, valve spring kits and ignitions are also available.

EFI Tuning and Mapping With the advent of modern Electronic Fuel Injection in today’s four-stroke engines, EFI tuning and mapping is nearly as complicated as suspension. Leave it to the experts at TBT to fine-tune your engine output to optimize your speed. Massive horsepower won’t get you far unless it makes it to the ground in the most effective way. Gain every advantage you can get on the track with the EFI tuning and mapping expertise of TBT Racing. Custom Coating So many factory secrets lie in the advanced coatings used on their components. DLC (Diamond Like Carbon), Ti Nitrate and hard anodizing are among coatings that can help reduce friction and optimize performance. Call for more details.