TSP Yamaha YZ125 2005-2021 & YZ125X 2020-2022 Billet Head

This head suits the models listed below:

YZ125 2005-2021 – See the listing for our 2022 model.

YZ125X 2020-2022 (current)

Choose your desired compression ratio from the drop down list.

Medium Compression: This design offers a similar compression ratio to the stock head, but with a much better design. Squish clearance is tighter than stock and the design is much more detonation resistant than the stock head. It offers improved power throughout the rev range and makes a great bike even better. It is best suited to high level MX riding or very fast riders who like to rev the engine hard.

High Compression: This design is slightly higher compression than the stock head but still safe for 98 RON pump fuel with appropriate jetting. It offers improved bottom/mid power over the Mid/High design and is best suited to trail riding, offroad racing or MX riders who want max midrange pull. It is also recommended for the YZ125X model and gives very linear, strong power delivery when the standard YZ125 model powervalve spring is used (we can supply this if necessary).

Our new TSP Billet cylinder heads are machined from solid 6061 T6 stock and offer improved performance, reliability and fuel economy. They are the best bolt on mod you can buy for your bike! Our design offers better heat dissipation than many other 2 piece designs due to the large lower section which incorporates the combustion chamber… this allows heat from combustion to disperse over a larger area than other 2 piece designs for improved heat transfer to the coolant.

These Billet machined 2 piece heads feature TSP’s proven combustion chamber designs and are a MUST HAVE mod for most current model offroad bikes. Our combustion chamber designs have been used by hundreds of happy customers and have been extensively dyno tested… the gains are consistent and include: increased power throughout the rev range (especially bottom/mid), improved fuel economy, greatly reduced risk of detonation, increased top end life in many models, and much SMOOTHER power delivery.

The unique Billet design has been 100% developed, machined and tested in-house at TSP.

These Billet heads will bolt onto your standard cylinder and are designed to work with standard base gaskets. If you are unsure of your current base gasket thickness we can advise the correct thickness to achieve the necessary cylinder height and squish clearance.

We can also advise baseline jetting specs to go with your new Billet head. The customer takes all responsibility for ensuring that jetting is appropriate for their riding style and conditions.

Below is a video with this head with our TSP ignition and scalvini pipe for the YZ125: