S3 - TRS Cylinder Head Inserts (Fits Original Head 2016 to 2025) 250 / 280 / 300cc

S3 replacement inserts to fit the standard head on the TRS trials bikes.

Please Note:  The 2022 and 2023 UK suppiled TRS One R's came with a low compression head as standard in the UK only. The 2022 TRS One (+XTrack) and 2024 TRS One R is shown in the parts book as having a low compression head insert so I assume this is world wide.

Some inserts are designed to fit the BPMR6A spark plug and some the longer BPR5ES plug. Please contact us if you would like us to check what style is in stock before ordering (low comp only available in the long plug version).  Both styles will fit all bikes, but the correct spark plug and tank is needed. The 2018 Gold model was the first bike to use the longer plug and the newer tank to accommodate the longer plug. I'm fairly sure all the bikes since then come with the newer tank.

Available in Low & High Compression

The primary use of the Red higher compression heads are when riding at high altitude due to the air being less dense, they can also be used to increase the torque of the engine but be careful as raising the compression to much may lead to pre-ignition (pinking) and detonation which can damage your engine, a higher octane fuel may be required to prevent this from happening.

The Gold Low compression head is great for riders who want a soft power delivery, it makes the bike easier to ride especially in slippy muddy conditions. Great for beginner riders but even some expert riders use these to tame the bike down and make it easier and more forgiving to ride.

250 & 300 cc

ST-1071-300 (300 LOW)
ST-1072-300-A (300 HIGH)
ST-1246-280-B (280 LOW)
ST-1073-250 (250 LOW)
ST-1074-250-A (250 HIGH)