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Aftermarket Yamaha YZ250 Cylinder Heads — Bulk Supply for B2B Buyers Worldwide

Aftermarket Yamaha YZ250 Cylinder Heads — Bulk Supply for B2B Buyers Worldwide

We supply aftermarket Yamaha YZ250 cylinder heads to two-stroke engine builders, motocross and off-road distributors, and OEM brands worldwide. The YZ250 is a 249cc liquid-cooled reed-valve two-stroke, so its head is a billet or cast combustion-chamber cap with a squish band, coolant jacket, and central spark-plug bore — no valvetrain. We CNC-machine from 6061-T6 billet for the squish band, chamber volume, and sealing face, and pressure-test every unit. Coverage centers on the long-stroke 1999-onward engine, the earlier 247cc and air-cooled families, and the YZ250X off-road variant. MOQ 500 pieces per SKU, samples accepted, ISO 9001 certified.

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Technical Specifications: Yamaha YZ250 Cylinder Heads

The YZ250 head is a two-stroke combustion-chamber cap — no valves, seats, or guides. It seals the top of the cylinder and carries the squish band, the coolant jacket, and a central spark-plug bore. The defining feature of this engine is its long stroke. Since 1999 the YZ250 has run a 66.4mm bore and a 72mm stroke for 249cc, after earlier 68 × 68mm (247cc) and 70 × 64mm air-cooled versions. The long-stroke layout lowers the redline a little and trades a bit of top-end for much stronger low- and mid-rpm torque. That torque character is exactly why squish and chamber shape matter: get them right and the engine pulls hard off the bottom without detonating; get them wrong and you lose the YZ250's best trait. We cut squish to your piston, base-gasket stack, and fuel. Our motorcycle cylinder head program covers the YZ250 across its engine families, including the post-2011 global-spec head.

SpecificationStandard Value
Engine PlatformYamaha YZ250 motocross two-stroke. YZ250X off-road variant supported — specify model and year in RFQ.
Engine Type2-stroke, single cylinder, reed-valve induction (reed block integral to the cylinder), liquid-cooled, YPVS power valve
Displacement249cc (1999-onward long-stroke). 247cc on earlier 68 × 68mm engines.
Bore × Stroke66.4mm × 72mm (1999-onward). Earlier: 68 × 68mm (247cc) and 70 × 64mm (early air-cooled). Confirm year — chamber bore differs.
Head TypeTwo-stroke combustion-chamber head — no valvetrain. Single central spark-plug bore, integrated squish band and coolant jacket.
Construction OptionsSolid billet head, or modular two-part head with a swappable chamber insert for ratio changes. Gravity-cast version offered where unit cost is the priority.
Material6061-T6 billet as standard — its higher thermal conductivity pulls chamber heat faster on a hard-run 250. A356-T6 cast for economy tiers; 7075 supplied on request.
Squish ClearanceCut to your piston deck height and base-gasket stack. A tighter, piston-matched squish recovers the bottom/mid torque this long-stroke engine is built for.
Compression OptionsChamber volume set to your ratio. Medium profile for smoother, higher-revving MX; high profile for maximum bottom/mid grunt; race-fuel and altitude profiles on request.
Global-Spec NoteThe post-2011 global-spec head runs different squish/chamber detail from pre-2011 heads. Many builders prefer a re-profiled chamber for MX. Specify your preference.
CoolingGenerous coolant jacket sized for sustained MX heat load. The modular two-part design routes more coolant around the chamber wall.
SealingBillet heads seal on O-rings (supplied with the head plus copper washers); cast designs use a head gasket.
Deck/Sealing Flatness≤ 0.02mm (CMM verified on every unit)
Supply OptionsFinished billet head, cast blank, or modular head with selectable chamber insert. Private-label engraving available.
Surface FinishAs-machined, bead-blasted, or anodized (black/blue/custom) on request


Key Sourcing Information at a Glance

ParameterDetail
Product TypeAftermarket YZ250 two-stroke cylinder heads — finished billet, cast blank, or two-piece dome design. Built to fit the Yamaha YZ250 engine; this is a replacement and performance part, not an original-equipment Yamaha component.
MOQ500 pieces per SKU for standard variants. Sample orders of 50-100 pieces accepted for first-time buyers. CNC billet runs of 100-300 pieces accepted for performance brands.
Lead Time30-45 days for stock variants. 45-70 days for new billet programs, custom squish/compression specs, or two-piece dome tooling.
Generation Compatibility1999-onward long-stroke 249cc engine (the high-volume family), earlier 247cc engines, and the YZ250X off-road variant. Post-2011 global-spec head differs in squish/chamber — confirm year and preference.
Material6061-T6 billet (standard for performance heads) or A356-T6 cast. Material certificates provided.
Custom Spec InputsTarget compression ratio, fuel grade (pump vs race), squish clearance, base-gasket thickness, riding use (MX vs off-road), and altitude. We advise baseline gasket and squish stack on request.
Quality Verification100% pressure leak testing. CMM verification of squish band, chamber volume, and sealing face. Spectrometer-verified material. Batch records archived for 5 years.
PackagingStandard export carton, neutral packaging, or private-label cartons. Billet heads ship with O-rings and copper washers.
Shipping TermsFOB Ningbo/Shanghai, CIF, or DDP. Export experience to the US, Australia, Europe, and Southeast Asian two-stroke markets.
Documentation ProvidedMaterial certificate, CMM inspection report, leak test record, batch traceability, ISO 9001 certificate, commercial invoice, packing list, certificate of origin.


How to Source the Right YZ250 Head: Long Stroke, Global Spec, and Pitfalls

The YZ250 has been in production since 1974 and, unlike the YZ125, its core engine has stayed largely stable since 1999. That makes generation sourcing easier in one way and trickier in another — the head family is huge, but a few specific changes matter. 1999-Onward Long-Stroke Engine (66.4 × 72mm, 249cc) This is the engine most buyers need and the highest-volume head family. The long stroke gives the YZ250 its strong bottom-to-mid torque. Head bore and chamber are sized for this layout. If a bike is a 1999-or-newer YZ250, this is almost certainly the head family, with the global-spec note below. Pre-1999 Engines (68 × 68mm and earlier air-cooled) Earlier liquid-cooled 247cc and the original air-cooled engines use different bore and chamber dimensions. Heads for these are lower-volume restoration items and carry their own tooling. Quote the exact year. Post-2011 Global-Spec Head Around the global-spec emissions update, Yamaha revised the head's squish and chamber detail. A number of MX builders re-profile the chamber or move to a tighter squish for sharper power. We can supply either the global-spec geometry or a re-profiled MX chamber — tell us which you want. YZ250X Off-Road Variant The YZ250X cross-country model shares the core engine but is tuned for off-road, and the ideal chamber and compression can differ from the MX bike. Confirm the model and intended use so we recommend the right profile. Why squish and chamber shape decide YZ250 head quality On a two-stroke there is no valve job, so head quality is the squish band and chamber. A wide, loosely toleranced squish invites detonation, fussy jetting, and lost torque — the opposite of what this long-stroke engine is good at. A tighter squish profiled to the piston shields the end gas and sharpens combustion, which is why a precision-machined head beats a generic one. Common avoidable mistakes when buying Confusing the YZ250 with the YZ250F. The YZ250 is a two-stroke with a combustion-chamber head. The YZ250F is a four-stroke with a DOHC titanium-valve head. Despite the names, almost no parts cross over. This is the single most common mix-up on the platform. Ordering by displacement alone. “250” two-stroke still spans a long-stroke 249cc and an older 247cc. Quote the model year. Ignoring the piston and gasket stack. Squish is set by head geometry plus base-gasket thickness and piston deck height. Send your piston and base-gasket spec or the squish figure is a guess. Skipping material choice. 6061 billet sheds heat better than 7075 or cast on a hard-run 250. For racing or hot climates, specify 6061-T6.

Aftermarket Yamaha YZ250 Cylinder Heads — Bulk Supply for B2B Buyers Worldwide

Who We Supply

For Two-Stroke Engine Builders

Mixed-spec orders supported across the 1999-onward long-stroke engine, earlier families, and the YZ250X (300-2,000 pieces per SKU). Builders we supply keep parallel stock because customers run MX and off-road setups on different fuel grades. We machine squish and chamber volume to your target and include a CMM report on every batch. Sample qualification runs of 50-100 pieces accepted before bulk commitment.


For Motocross & Off-Road Distributors

Private label and neutral packaging available. We support drop-shipping to consolidation warehouses and regional hubs across North America, Europe, and Australia. The YZ250 head is a durable aftermarket line because the bike has stayed in production for decades and the installed base is enormous. Distributors stocking multiple Yamaha two-stroke SKUs typically run quarterly consolidated shipments.


For Performance & Tuning Brands

CNC billet programs in small batches. We produce one-piece billet heads and two-piece designs with interchangeable domes for compression tuning, machined from 6061-T6 for thermal performance. Medium and high-compression chamber profiles, pump-fuel and race-fuel options, and squish cut to the piston. Runs of 100-300 pieces accepted for qualified performance brands. Specify compression, fuel grade, squish target, riding use, and altitude.


For OEM & Private-Label Programs

Long-term OEM and private-label supply with capacity reservation. We supply heads to listed motorcycle manufacturers under multi-year agreements and accept proprietary CAD (STEP/IGES) for build-to-print work. In-house tooling and billet programming typically take 45-70 days from approved DFM to first-article approval. Custom anodizing and engraving for brand identity supported.


Frequently Asked Questions

What is your minimum order quantity for aftermarket YZ250 cylinder heads?

Standard MOQ is 500 pieces per SKU for variants in our production library, covering the 1999-onward long-stroke engine, earlier families, and YZ250X. Sample qualification orders of 50-100 pieces are accepted for new clients, and CNC billet runs of 100-300 pieces for performance brands. Long-term OEM MOQ is structured around your annual forecast.

Is the YZ250 head the same as the YZ250F head?

No, and this is the most common mix-up on the platform. The YZ250 is a two-stroke, so its head is a combustion-chamber cap with a squish band and no valvetrain. The YZ250F is a four-stroke with a DOHC head, titanium valves, seats, and guides. The names are almost identical but the parts do not cross over. Always confirm whether you need the two-stroke YZ250 or the four-stroke YZ250F.

How do I identify which YZ250 head generation I need?

Use the model year. 1999-onward bikes use the long-stroke 249cc engine, which is the high-volume head family. Pre-1999 bikes use a 247cc or older air-cooled engine with different bore and chamber dimensions. The post-2011 global-spec head also differs in squish detail. Send a photo of the engine number or the model year and we will confirm the correct head within 24 hours.

What does the long stroke mean for head and chamber choice?

Since 1999 the YZ250 uses a 66.4mm bore and a 72mm stroke. The long stroke lowers the redline slightly and shifts the engine's strength toward bottom and mid-range torque. The head bore and chamber are sized for this layout, and the squish and compression should be chosen to support that torque character rather than chasing top-end it was not built for. Tell us your riding use and we will recommend a chamber profile.

What is the post-2011 global-spec head, and should I avoid it?

Around the global-spec emissions update after 2011, Yamaha revised the head's squish and chamber. It is not a part to avoid, but many MX builders prefer a re-profiled chamber or a tighter squish for sharper power. We can supply either the global-spec geometry as-is or an MX-oriented re-profile. Specify your preference and intended use.

Do you make billet heads with adjustable compression?

Yes. We produce two-piece heads with interchangeable domes so you can change compression and chamber profile without replacing the whole head, plus one-piece billet heads cut to a fixed ratio. Medium-compression profiles give smoother power that revs harder; high-compression profiles maximize bottom and mid. Pump-fuel, race-fuel, and high-altitude options available. Tell us your target ratio, fuel grade, and riding use.

Can these heads fit the YZ250X?

In most cases yes. The YZ250X cross-country variant shares the core YZ250 engine, but it is tuned for off-road, so the ideal chamber and compression can differ from the MX bike. Confirm the model and intended use and we will match the right head and recommend a profile.

What material do you use, and is 6061 better than 7075 or cast?

Our standard performance material is 6061-T6 billet, which conducts heat better than 7075 and better than cast alloys — an advantage on a hard-run two-stroke that needs to shed chamber heat. A356-T6 cast is available for economy tiers, and 7075 on request, though 6061 is usually the better thermal choice for this head. All material is spectrometer-verified.

What is the typical lead time?

30-45 days for variants in our standard library, from PO confirmation to FOB-ready. 45-70 days for new billet programs, custom squish/compression specs, or two-piece dome tooling. Bulk reorders on existing programs ship within 21-30 days for established customers.

What other YZ250 engine parts do you supply besides cylinder heads?

Our primary focus is cylinder heads. We also produce engine covers and intake-related castings, and can quote cylinders and crankcase components for the YZ250 platform on request. For distributors building a full YZ250 top-end range, list the parts and volumes in your RFQ for a consolidated quote.

Why B2B Buyers Source YZ250 Cylinder Heads From Feiya

• 17 years of motorcycle cylinder head production — with dedicated tooling and CMM reference data for the long-stroke 1999-onward engine, earlier families, and the YZ250X.

• Squish and chamber tuned to the long-stroke torque character — squish band and chamber volume CMM-verified on every unit and profiled to the OEM piston, the dimension that decides YZ250 head performance.

• Global-spec or re-profiled MX chambers — we supply the post-2011 global-spec geometry as-is or an MX-oriented re-profile, so builders get the power character they want.

• 6061-T6 billet capability — one-piece and two-piece dome designs machined in-house, with the thermal advantage 6061 holds over 7075 and cast on a hard-run two-stroke.

• Largest cylinder head manufacturer in Yueqing City — 17,000+ m² facility, 5,000+ tons annual aluminum casting capacity, 125+ CNC machining centers, ISO 9001 certified and a National High-Tech Enterprise supplying listed motorcycle brands.

Get a Quote for Your YZ250 Cylinder Head Requirements

Send your YZ250 model year (or engine family — 1999-onward long-stroke, earlier 247cc, or YZ250X), construction preference (billet, two-piece dome, or cast), and target volume. For performance heads, include your target compression ratio, fuel grade, squish clearance, piston model, base-gasket thickness, and whether the build is MX or off-road so we set the chamber and stack correctly. For OEM and private-label programs, include drawings (STEP/IGES) and any anodizing or engraving requirements. Our engineering team responds within 24 hours.