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Aftermarket Yamaha PW50 Cylinder Heads — Bulk Supply for B2B Buyers Worldwide

Aftermarket Yamaha PW50 Cylinder Heads — Bulk Supply for B2B Buyers Worldwide

We supply aftermarket Yamaha PW50 cylinder heads to minibike engine rebuilders, youth-bike parts distributors, and OEM brands worldwide. The PW50 is a 49cc air-cooled reed-valve two-stroke, so its head is a finned aluminum combustion-chamber cap with a central spark-plug bore and no coolant jacket and no valvetrain. The PW50 has run essentially unchanged since 1980, so one head family covers the whole production run. We cast or CNC-machine the chamber, cooling fins, and sealing face, and pressure-test every unit. MOQ 500 pieces per SKU, sample orders accepted, 17 years of mass production, ISO 9001 certified.

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Technical Specifications: Yamaha PW50 Cylinder Heads

The PW50 head is different from the liquid-cooled two-stroke heads on Yamaha's YZ race bikes. The PW50 engine is a 49cc air-cooled reed-valve two-stroke with a 40mm bore and 39.2mm stroke, a single-speed automatic, shaft final drive, and Autolube oil injection. Because it is air-cooled, the head has cooling fins instead of a coolant jacket, and it sheds heat to the air rather than to coolant. There is no valvetrain and no liquid cooling. The other thing that makes this part simple to source is consistency: the PW50 has been in production with the same basic engine since 1980, so there are no confusing generation splits — one head family fits the whole run. The two practical needs are faithful stock-replacement heads for the huge installed base of kids' bikes, and matched heads for big-bore kits. Our motorcycle cylinder head program covers both.

SpecificationStandard Value
Engine PlatformYamaha PW50 (PeeWee 50) youth minibike. One head family covers the full 1980-onward production run.
Engine Type2-stroke, single cylinder, reed-valve (case-reed) induction, air-cooled
Displacement49cc (nominal 50cc)
Bore × Stroke40.0mm × 39.2mm (OEM Yamaha spec)
Head TypeAir-cooled two-stroke head — finned, no coolant jacket, no valvetrain. Central spark-plug bore and integrated combustion chamber.
CoolingAir-cooled via cast cooling fins. Fin area and casting quality set how well the head sheds heat.
Fuel / Oil SystemVM12 carburetor with Autolube oil injection (no premix). Head is the same regardless of fuel detail.
CompressionMild OEM compression tuned for safe, gentle beginner power. Chamber volume held to OEM for stock heads; adjustable for big-bore builds.
Big-Bore CompatibilityHeads available matched to common PW50 big-bore kits. Specify the kit bore so the chamber and squish suit the larger piston.
MaterialA356 aluminum alloy (JIS AC4CH equivalent), T6 heat treated. 6061-T6 billet available for big-bore or premium variants.
Casting MethodGravity die casting (standard for this finned head). CNC-machined billet available for big-bore and premium tiers.
Deck/Sealing Flatness≤ 0.02mm (CMM verified on every unit)
SealingHead-gasket sealed to OEM design. Gaskets supplied on request.
Supply OptionsFinished cast head / CNC-machined billet head / big-bore-matched head. Private-label engraving available.
Surface FinishAs-cast, bead-blasted, or anodized/painted (black/blue/custom) on request


Key Sourcing Information at a Glance

ParameterDetail
Product TypeAftermarket PW50 air-cooled cylinder heads — cast, billet, or big-bore-matched. Built to fit the Yamaha PW50 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. Billet/big-bore runs of 100-300 pieces accepted.
Lead Time30-45 days for stock variants. 45-70 days for new billet programs or big-bore-matched tooling.
Model CoverageOne head family across the full PW50 run from 1980. No generation matching required — confirm stock or big-bore application only.
MaterialA356 aluminum (JIS AC4CH equivalent), T6 heat treated. 6061-T6 billet for big-bore/premium tiers. Material certificates provided.
Custom Spec InputsFor big-bore heads: kit bore size, target compression, and fuel grade. For stock heads: OEM-spec, no extra input needed.
Quality Verification100% pressure leak testing. CMM verification of chamber, deck flatness, and fin/bolt features. Spectrometer-verified material. Batch records archived for 5 years.
PackagingStandard export carton, neutral packaging, or private-label cartons. High-volume cartoning for youth-bike parts programs.
Shipping TermsFOB Ningbo/Shanghai, CIF, or DDP. Export experience to the US, Australia, Europe, and other youth-minibike 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 PW50 Head: Air-Cooled Simplicity and a Few Pitfalls

The PW50 is the easiest head on the Yamaha off-road line to source, because the engine has barely changed in over four decades. The work is mostly about getting the air-cooled details right and deciding stock versus big-bore. One Head Family Since 1980 The PW50 has been in production since 1980 with the same basic 49cc air-cooled engine. Unlike the YZ two-strokes, there are no generation splits to track and no carb-versus-FI question — it stays carbureted with Autolube. A buyer almost never needs to match a model year, only confirm whether the head is for a stock bike or a big-bore build. Air-Cooled, Not Liquid-Cooled This is the detail that separates a PW50 head from a YZ85 or YZ125 head. The PW50 head is finned and sheds heat to the air; it has no coolant jacket. Fin area, casting soundness, and good heat conduction are what keep a kids' bike from running hot during a long first ride. A poorly cast finned head with internal porosity runs hotter and risks detonation, so casting quality matters even on a mild engine. Stock Replacement vs Big-Bore Most PW50 head demand is plain replacement for the enormous installed base of beginner bikes. A smaller niche fits big-bore kits, where the cylinder is bored to a larger piston and the head chamber and squish should be matched to suit. These are different products. For big-bore heads, tell us the kit bore, target compression, and fuel. Common avoidable mistakes when buying Treating the PW50 like a liquid-cooled race two-stroke. It is air-cooled with a finned head and no coolant jacket. The cooling design and the casting priorities are different. Ordering a stock head for a big-bore engine. If the cylinder has been bored for a big-bore kit, a stock-chamber head may not suit the larger piston. State the kit bore. Overlooking casting quality because the engine is mild. Low power does not excuse a porous head. We pressure-test every unit, because a hidden casting flaw on a child's bike is still a field failure. Ignoring the gasket. The PW50 head is gasket-sealed to the OEM design. Confirm whether you need gaskets supplied with the heads.

Aftermarket Yamaha PW50 Cylinder Heads — Bulk Supply for B2B Buyers Worldwide

Who We Supply

For Minibike Engine Rebuilders

High-volume stock-replacement orders supported, with one head family covering the full PW50 run (500-3,000 pieces per SKU). Rebuilders we supply keep steady stock because the PW50 is a first bike for huge numbers of kids and its parts cycle through dealerships year after year. We include a CMM report on every batch and pressure-test each head. Sample qualification runs of 50-100 pieces accepted before bulk commitment.


For Youth-Bike Parts Distributors

Private label and neutral packaging available. We support drop-shipping to consolidation warehouses and regional hubs across North America, Europe, and Australia, where the PW50 has the largest youth following. Because the engine has not changed, you can stock one head SKU with confidence rather than juggling generation variants. Distributors typically run quarterly consolidated shipments.


For Big-Bore & Tuning Brands

Big-bore and tuning heads in small batches. For shops building PW50 big-bore kits, we machine heads matched to the larger bore, with chamber and squish set to the kit and fuel. Cast or 6061-T6 billet, depending on the tier. Runs of 100-300 pieces accepted for qualified brands. Specify kit bore, target compression, and fuel grade.


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 typically takes 45-70 days from approved DFM to first-article approval. Custom anodizing, painting, and engraving for brand identity supported.


Frequently Asked Questions

What is your minimum order quantity for aftermarket PW50 cylinder heads?

Standard MOQ is 500 pieces per SKU for stock variants, with one head family covering the full PW50 production run. Sample qualification orders of 50-100 pieces are accepted for new clients, and billet or big-bore runs of 100-300 pieces for performance brands. Long-term OEM MOQ is structured around your annual forecast.

Does the PW50 head change between model years?

No, for practical purposes. The PW50 has used the same basic 49cc air-cooled engine since 1980, so one head family fits the whole run. There are no carb-versus-FI or major generation differences to track. You only need to tell us whether the head is for a stock bike or a big-bore build.

How is the PW50 head different from a YZ85 or YZ125 head?

The PW50 head is air-cooled, with cooling fins and no coolant jacket, while the YZ85 and YZ125 heads are liquid-cooled with a coolant jacket and a tightly machined squish band. The PW50 engine is also milder and lower-revving. The casting priorities differ: on the PW50 the fin area and casting soundness handle the heat that a coolant jacket would handle on a YZ.

Do you make heads for PW50 big-bore kits?

Yes. For PW50 big-bore kits, where the cylinder is bored to a larger piston, we machine heads with the chamber and squish matched to the kit so the larger piston runs correctly. These can be cast or 6061-T6 billet. Lead time is 45-70 days. Specify the kit bore size, target compression, and fuel grade with your inquiry.

Is the head air-cooled or liquid-cooled?

Air-cooled. The PW50 engine sheds heat through cast cooling fins on the head and cylinder rather than through a coolant jacket. This is a core difference from Yamaha's liquid-cooled YZ two-strokes, and it shapes how the head is cast — fin area and a sound, dense casting are what keep the head running at a safe temperature.

Do you supply head gaskets with the heads?

Yes, on request. The PW50 head is gasket-sealed to the OEM design, and we can supply the head gasket with the heads or ship bare heads if you stock gaskets separately. Tell us which you prefer in your RFQ.

Why does casting quality matter on such a mild engine?

Because a hidden casting flaw is still a field failure, even on a 3-horsepower kids' bike. Internal porosity makes a head run hotter and can lead to detonation or a coolant-path leak in the wrong place. We pressure-test every head and CMM-verify the chamber and deck so a mild engine still gets a sound, consistent part.

What material and casting method do you use?

Primary alloy is A356 aluminum (JIS AC4CH equivalent), T6 heat treated, with material certificates. Standard process for this finned head is gravity die casting; 6061-T6 billet is available for big-bore and premium tiers. All material is spectrometer-verified before melting.

What is the typical lead time, and do you export to my market?

30-45 days for stock variants, from PO confirmation to FOB-ready, and 45-70 days for new billet or big-bore tooling. We have export experience to the US, Australia, Europe, and other youth-minibike markets, with FOB, CIF, and DDP terms and full export documentation.

What other PW50 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 PW50 platform on request. For distributors building a full PW50 top-end range, list the parts and volumes in your RFQ for a consolidated quote.

Why B2B Buyers Source PW50 Cylinder Heads From Feiya

• One head family across the entire PW50 run — because the engine has barely changed since 1980, you stock a single head SKU with confidence instead of tracking generations.

• Air-cooled casting done right — sound, dense finned castings that shed heat properly, CMM-verified for chamber and deck and pressure-tested on every unit, so a kids' bike head stays cool and reliable.

• Stock and big-bore from one supplier — faithful OEM-spec replacement heads for the huge installed base, plus big-bore-matched heads for tuning kits, cast or 6061-T6 billet.

• Largest cylinder head manufacturer in Yueqing City — 17,000+ m² facility, 5,000+ tons annual aluminum casting capacity, 125+ CNC machining centers, built for high-volume youth-bike parts supply.

• ISO 9001 certified facility — recognized as a National High-Tech Enterprise and a Technology-Based SME of Zhejiang Province, supplying listed motorcycle brands under multi-year OEM contracts.

Get a Quote for Your PW50 Cylinder Head Requirements

Send whether you need stock-replacement or big-bore-matched heads, your target volume, construction preference (cast or billet), destination port, and preferred Incoterms. For big-bore heads, include the kit bore size, target compression, and fuel grade. For OEM and private-label programs, include drawings (STEP/IGES) and any anodizing, painting, or engraving requirements, plus whether you want head gaskets supplied. Our engineering team responds within 24 hours.