{"product_id":"castair-4-5-hp-single-stage-v2-cylinder-air-compressor-bare-pump-with-12-5-2a-flywheel-od-48-oz-oil-capacity-va80","title":"Castair, 4-5 HP Single Stage, V2 Cylinder Air Compressor Bare Pump, with 12.5 - 2A Flywheel OD, 48 oz. Oil Capacity VA80","description":"\u003cp\u003eThe Castair VA80 is a 4-5 HP single-stage, V2 cylinder air compressor bare pump — the cast iron heart of a Castair compressor. This is a complete pump assembly: two cylinders in a V configuration, crankcase, connecting rods, pistons, valves, and cylinder head, all assembled and ready to mount. It's designed for compressors needing a 12.5-2A flywheel (12.5\" outer diameter) and holds 48 oz. of oil. At $976.36, this is a serious replacement component — you're buying this when a pump rebuild isn't practical or cost-effective and you need a direct-fit OEM replacement to get the compressor back in service.\u003c\/p\u003e\n\n\u003ch2\u003eWho Needs a Bare Pump Replacement\u003c\/h2\u003e\n\u003cp\u003eA bare pump makes sense in two scenarios. First: the motor and tank are in serviceable condition but the pump has failed — scored cylinders, cracked crankcase, seized crankshaft, or catastrophic valve failure that makes rebuild impractical. Second: you're building a compressor from scratch using a tank, motor, and separate components, and need a Castair pump to match the rest of the Castair hardware. In both cases, the VA80 provides a factory-fresh pump without the cost of a complete compressor unit.\u003c\/p\u003e\n\n\u003ch2\u003eV2 Cylinder Configuration\u003c\/h2\u003e\n\u003cp\u003eThe V2 designation means two cylinders arranged in a V pattern — this is the classic configuration for single-stage reciprocating compressor pumps. The V layout balances the reciprocating forces better than an inline configuration, reduces vibration, and allows a more compact pump design for a given displacement. Single-stage means both cylinders compress air in a single pass from atmospheric to discharge pressure — this is appropriate for compressors delivering air at typical shop pressures (up to 135-150 PSI depending on the design).\u003c\/p\u003e\n\n\u003ch3\u003eKey Specifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eConfiguration:\u003c\/strong\u003e Single-stage, V2 (two cylinders, V arrangement)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHP Range:\u003c\/strong\u003e 4-5 HP motor range — size the motor to this range for correct pump speed and output\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlywheel Compatibility:\u003c\/strong\u003e 12.5-2A flywheel outer diameter (12.5\" OD) — critical for matching belt drive from the motor to the pump crankshaft\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOil Capacity:\u003c\/strong\u003e 48 oz. (1.5 quarts) — use Castair-specified non-detergent compressor oil\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConstruction:\u003c\/strong\u003e Cast iron cylinders, cylinder head, and crankcase — cast iron handles heat and wear better than aluminum for pump bodies in continuous use\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBare Pump:\u003c\/strong\u003e Pump assembly only — does not include motor, flywheel, belt, pulley, or tank\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat Causes a Pump to Fail\u003c\/h2\u003e\n\u003cp\u003eUnderstanding why pumps fail helps prevent repeat failures after replacement:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOil Starvation:\u003c\/strong\u003e Running with low or no oil causes cylinder scoring, bearing seizure, and crankshaft failure. Check oil level every 100 hours or monthly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWrong Oil Type:\u003c\/strong\u003e Detergent motor oil breaks down in compressor service and leaves deposits. Use non-detergent 30-weight compressor oil only.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOil Contamination:\u003c\/strong\u003e Water in the oil (from condensation in humid environments) emulsifies the oil and destroys bearing surfaces. Change oil more frequently in humid climates.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eValve Failure:\u003c\/strong\u003e Worn or broken intake or discharge valves cause the pump to work harder and build heat, leading to secondary failures. Valve replacement is part of normal maintenance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOverheating:\u003c\/strong\u003e Running the compressor above its duty cycle causes heat buildup that leads to valve failure and oil breakdown. A 4-5 HP pump like the VA80 has a duty cycle limit — don't exceed it.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Requirements\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMotor:\u003c\/strong\u003e 4-5 HP electric motor, sized to match your voltage and phase (this pump is sold bare — motor not included)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlywheel:\u003c\/strong\u003e 12.5-2A series flywheel — the flywheel OD and bore must match your motor shaft diameter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBelt:\u003c\/strong\u003e V-belt sized for the pulley\/flywheel combination — calculate belt speed based on your target pump RPM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTank:\u003c\/strong\u003e Appropriately sized air tank with matching discharge port size\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCheck Valve:\u003c\/strong\u003e Install a check valve between pump discharge and tank — do not connect the pump directly to a pressurized tank line without a check valve\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlex Hose:\u003c\/strong\u003e Use an appropriate metal flex hose between pump outlet and tank fitting — see the VA series flex hose lineup\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOil:\u003c\/strong\u003e Fill to the dipstick full mark with non-detergent 30-weight compressor oil before first start\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eBreak-In Procedure\u003c\/h2\u003e\n\u003cp\u003eA new bare pump requires a break-in period to seat the rings and valves properly:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFill with correct oil before first start — do not dry-run even briefly\u003c\/li\u003e\n\u003cli\u003eRun the pump unloaded for the first 15-30 minutes — disconnect or plug the discharge to allow air to bleed off without building pressure\u003c\/li\u003e\n\u003cli\u003eCheck for oil leaks, unusual noise, and proper operation during break-in\u003c\/li\u003e\n\u003cli\u003eChange the oil after the first 50 hours — the initial oil will contain break-in wear particles\u003c\/li\u003e\n\u003cli\u003eResume normal oil change intervals after the first change\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1x Castair VA80 Bare Pump Assembly — 4-5 HP, V2 Single Stage\u003c\/li\u003e\n\u003cli\u003eOil fill and dipstick (integrated with pump)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eAdditional hardware included with the bare pump (gaskets, valve components, etc.) is not confirmed from manufacturer data. Contact us for a complete parts list before ordering.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eWhen Does a Shop Need This vs. Other Options\u003c\/h2\u003e\n\u003cp\u003eThe VA80 makes financial sense when the cost of a new complete compressor is significantly higher than motor + tank (still good) + this pump. On a 5 HP compressor, a new complete unit might run $800-$1,500 depending on tank size and features. If your motor and tank are sound, a $976.36 bare pump replacement gives you a factory-fresh pump and keeps your existing installation. If the motor is also shot, you might be better off with a complete replacement unit — call us and we'll run the numbers with you.\u003c\/p\u003e\n\u003cp\u003eThe VA80 is also the right choice if you're maintaining a fleet of identical Castair compressors and want to keep spare pump inventory — replacing a pump in the field is faster than waiting on a new complete unit.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e VA80\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air \/ Castair\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Bare pump assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStage:\u003c\/strong\u003e Single-stage\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCylinder Configuration:\u003c\/strong\u003e V2 (two cylinders)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHP Rating:\u003c\/strong\u003e 4-5 HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlywheel OD:\u003c\/strong\u003e 12.5\" (12.5-2A series)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOil Capacity:\u003c\/strong\u003e 48 oz. (non-detergent 30-weight compressor oil)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Major Components\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $976.36\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eRPM range, CFM output, maximum pressure rating, and exact dimensions were not available from manufacturer data at time of writing. Contact us for full technical specifications before purchase.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCastair Specialist:\u003c\/strong\u003e We stock Castair bare pump assemblies and can help confirm compatibility with your motor, flywheel, and tank before you order\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree Shipping:\u003c\/strong\u003e On qualifying orders — contact us about shipping for large components\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree Tech Support:\u003c\/strong\u003e Call 866-217-0063 — pump replacement questions, belt sizing, break-in procedures — we handle these regularly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull Manufacturer Warranty:\u003c\/strong\u003e Castair factory warranty on all new pump assemblies\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHonest Buying Advice:\u003c\/strong\u003e We'll tell you if a complete replacement unit makes more sense than this pump for your situation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342610489557,"sku":"VA80","price":1800.56,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/CastAirTwoStageAirCompressorPump_7610c49b-6e6b-4c69-88e3-8636b05413e7.png?v=1772652964","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-4-5-hp-single-stage-v2-cylinder-air-compressor-bare-pump-with-12-5-2a-flywheel-od-48-oz-oil-capacity-va80","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}