VHM cylinder head Rieju MR 250 / MR 300 21-25 / GasGas EC 250 / EC 300 18-19 + insert E 27.50 cc

HEAD AND INSERT INCLUDED: VHM head AA33201 + insert AE32320-E (combustion chamber 27.50 cc). Once fitted the head is ready to ride, nothing else to buy. Golden VHM two-stroke cylinder head with an exchangeable combustion chamber. It is designed to keep the engine's power throughout the whole race, not just the first laps: the improved water duct takes heat away from the combustion chamber more effectively. Made from a high-quality alloy and sealed with O-rings instead of a conventional gasket. WHAT THE INSERT IS AND WHY YOU NEED IT The VHM head has two parts: the golden cooled body and the chamber fitted into it — the insert. The insert sets the combustion chamber volume, i.e. the compression. Smaller volume = higher compression = more pull, but it needs higher-octane fuel. Larger volume = lower compression = the engine revs out more freely and tolerates pump fuel. When you change fuel, track or elevation you swap only the insert, not the whole head. WHICH INSERT TO CHOOSE (OEM piston) • AE32321-B — 19.50 cc, RIEJU MR250 '21-25, GasGas EC250 '18-19 • AE32321-C — 20.00 cc, RIEJU MR250 '21-25, GasGas EC250 '18-19 (VHM standard: MR250 / EC250) • AE32321-E — 20.50 cc, RIEJU MR250 '21-25, GasGas EC250 '18-19 • AE32321-F — 21.00 cc, RIEJU MR250 '21-25, GasGas EC250 '18-19 • AE32320-C — 26.50 cc, RIEJU MR300 '21-25, GasGas EC300 '18-19 • AE32320-E — 27.50 cc, RIEJU MR300 '21-25, GasGas EC300 '18-19 (VHM standard: MR300 / EC300) • AE32320-F — 28.50 cc, RIEJU MR300 '21-25, GasGas EC300 '18-19 VHM STANDARD INSERT • AE32321-C (20.00 cc) — MR250 / EC250 • AE32320-E (27.50 cc) — MR300 / EC300 BENEFITS • more engine power • better heat transfer • more resistance to detonation • exchangeable combustion chambers Spare O-rings: seal kit SK33201. Fits: Rieju MR 300 (2021–2025); GasGas EC 300 (2018–2019); GasGas EC 250 (2018–2019); Rieju MR 250 (2021–2025).