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Gas Concrete Vibrator Parts by Northrock
About Gas Concrete Vibrator Parts by Northrock
Replacement parts for the Northrock PRO50 gas backpack concrete vibrator family, in both the legacy 2-Stroke configuration and the current Honda GXH50 4-Stroke. Engines, carburetors, transmissions, clutches, frames, harnesses, and the universal flex-shaft and head system, shipped from an authorized Northrock supply channel.
The Northrock PRO50 is the gas backpack concrete vibrator that lets a single operator carry the power unit and consolidate concrete in walls, columns, footings, and decks without dragging a corded vibrator or extension cords across the slab. Two motor configurations are in current circulation, the legacy PRO50 2-Stroke (2-cycle engine with a Walbro WYK-104 or WYK-144 carburetor, runs on pre-mixed fuel) and the current PRO50 4-Stroke, also branded the Pro 50-4S (Honda GXH50 engine, runs on straight unleaded gasoline with no fuel mixing). Both motors share the same universal square-drive shaft interface and the same flexible-shaft and vibrator-head inventory.
DanseUSA is an authorized Northrock dealer stocking OEM parts for both configurations, from complete engine and clutch assemblies down to individual gaskets, jets, bearings, and shoulder strap hardware. Engine and drivetrain parts are model-specific, while flexible shafts and vibrator heads work across the line.
To order parts for your specific unit, go to the PRO50 4-Stroke Backpack Vibrator Parts page or the PRO50 2-Stroke Backpack Vibrator Parts page. For the full Northrock equipment catalog including ceiling grinders, rebar rockers, and electric vibrators, see the Northrock Parts hub.
| Specification | Detail |
|---|---|
| PRO50 4-Stroke Engine | Honda GXH50, 2.5 HP, 50cc, 4-stroke (Northrock P/N 555C2) |
| PRO50 4-Stroke Fuel | Straight unleaded gasoline, no oil mixing required |
| PRO50 2-Stroke Engine | 2-cycle gasoline engine with Walbro WYK-104 or WYK-144 carburetor |
| PRO50 2-Stroke Fuel | Pre-mixed unleaded gasoline plus 2-cycle engine oil |
| Vibration Frequency | 10,000 VPM (PRO50 4-Stroke per Northrock spec) |
| Shaft Connection | Universal square-drive with spring-pin lock (model-specific motor-side adapter) |
| Flexible Shaft Lengths | 7 ft, 10 ft, 14 ft standard, up to 21 ft for custom-reach work |
| Compatible Head Diameters | 3/4 in, 1 in, 1-1/4 in, 1-1/2 in, 1-3/4 in, 2 in, 2-1/2 in |
| Frame | Tubular steel with shoulder harness and vibration-isolating mounts (frame part numbers differ between 2-Stroke and 4-Stroke) |
| Country of Manufacture | Bohemia, NY, USA |
Engine, drivetrain, and frame parts are model-specific. Confirm your motor configuration before ordering drivetrain components.
4-Stroke Engine
PRO50 4-Stroke only. Complete Honda GXH50 4-stroke engine (P/N 555C2). For carburetor, recoil starter, ignition coil, air filter and other engine internals, see the Honda GXH50 service manual.
4-Stroke Transmission
PRO50 4-Stroke only. Transmission box (635A1) and cover (635B1), driven pulley (295N1), micro V belt (390B1), double-sealed bearings (140C300), end cap (215M1), drive core adapters (160CW1, 160CW2), casing adapter (150DE1).
4-Stroke Clutch
PRO50 4-Stroke only. Complete clutch assembly (25BA1), clutch drum pulley (295S1), clutch adapter (630A1), clutch shoes (625A1), clutch springs (465D1), double-shielded bearings (140D005), retaining ring (255F1), key (575D75).
2-Stroke Motor
PRO50 2-Stroke only. Complete piston (61122015), complete cylinder (61122014B), piston ring (94000015), flywheel (4191021A), spark plug (3055035), crankshaft bearings (3037014, 3035019, 3034012).
2-Stroke Carburetor (WYK-104 or WYK-144)
PRO50 2-Stroke only. Earlier units shipped with the Walbro WYK-104 (complete carb 2318890), later production switched to the WYK-144 (complete carb 2318630). The model code is stamped on the carburetor body. Some service parts are shared between variants, others are not, confirm against your stamping before ordering.
2-Stroke Starter and Clutch
PRO50 2-Stroke only. Complete starter (61042001B), starter rope (4098073), pawl (4191016), pawl spring (4191017A), pulley (4191018), clutch drum (405C1), clutch spring (4000132), clutch complete (4191153A).
4-Stroke Frame
PRO50 4-Stroke only. Complete frame assembly (440AV1), frame (440AT1), frame pad (445E1), engine mounting plate (215BR1), engine plate stand-offs (200AJ1), frame spacer (200AW1).
2-Stroke Frame and Harness
PRO50 2-Stroke only. Frame (62020031), complete frame variants (440N1, 440 P1), complete harness (62020039), shoulder pad (4100333), buckle set (62022030), engine isolator shock absorbers (3058011, 3058012).
4-Stroke Throttle
PRO50 4-Stroke only. Throttle control assembly with cable (605F1) and mounting screw (190F217). Ships pre-attached from the factory.
2-Stroke Handle and Throttle
PRO50 2-Stroke only. Complete handle (165G1 or 61042021A depending on production), throttle control (605A1, 605B1, 605C1), throttle cables (62010010, 615A1), switch (61040051), wiring harness (610A1).
Quick Disconnect
Universal interface, model-specific hardware. The 2-Stroke uses the Q.D. Release Complete (25AN1) with core adapter (160CY1). The 4-Stroke uses a multi-part assembly, drive core adapters L.H. (160CW1) and R.H. (160CW2), with casing adapter (150DE1). Both interfaces accept the same square-drive flexible shaft.
Flexible Shafts and Vibrator Heads
Universal inventory. Square-drive shafts in 7 ft, 10 ft, 14 ft, and up to 21 ft. Heads from 3/4 in through 2-1/2 in diameter. Heads are factory sealed in an oil bath and require zero maintenance, replace when amplitude drops or the eccentric tip shows wear.
High-wear consumables across the PRO50 line. Engine and clutch parts are model-specific, shaft and head wear items apply to both variants.
- Micro V belt (390B1) on the 4-Stroke is the single highest-wear drivetrain component. Replace when you hear belt slip on engagement, see glazing or cracking on the ribs, or notice reduced VPM under load.
- Walbro carburetor service kits on the 2-Stroke. The gasket and diaphragm kit (2318590) and repair kit (2318591) cover the most common hard-start and stall failures on the older 2-cycle engine. Confirm your carburetor stamping (WYK-104 or WYK-144) for any carb-specific parts.
- Spark plug on both models. The 2-Stroke uses 3055035. The 4-Stroke uses the Honda GXH50 specified plug, see the Honda service manual. A weak spark is the most common cause of a no-start on either configuration.
- Air filter element on both models. The 2-Stroke uses 61110010A sponge or 61120018 paper. The 4-Stroke uses the Honda GXH50 specified element. Concrete dust kills 2-cycle top ends and clogs 4-stroke intakes faster than anything else, inspect at every shift and clean or replace as needed.
- Flexible shaft inner core. Universal across both models. Inspect and re-lubricate every 50 hours of operation per the Northrock manual. Apply a 1/16 inch coating of high-quality lithium grease and do not over-grease.
- Quick disconnect release complete (25AN1) on the 2-Stroke. Replace when the spring pin no longer locks positively into the shaft adapter or when the square drive shows visible rounding. A worn QD will eject the shaft under load and is a safety issue.
Engine and drivetrain parts are completely different between the two configurations. The shaft and head system is universal. Confirm your motor before ordering drivetrain components.
| Component | PRO50 4-Stroke | PRO50 2-Stroke |
|---|---|---|
| Engine | Honda GXH50, 2.5 HP, 50cc, 4-stroke (555C2) | 2-cycle gasoline with Walbro WYK-104 or WYK-144 carb |
| Fuel | Straight unleaded gasoline | Pre-mixed gasoline and 2-cycle oil |
| Engine Maintenance | Oil changes per Honda GXH50 manual | No oil changes, but must mix every fill |
| Drive Belt | Micro V belt (390B1) | No belt, direct drive from crankshaft through clutch |
| Clutch | Complete assembly 25BA1, drum 295S1, shoes 625A1, springs 465D1 | Clutch complete 4191153A, clutch drum 405C1, clutch spring 4000132 |
| Frame | Complete frame 440AV1 with pad 445E1 | Frame 62020031 (also 440N1, 440 P1 variants) with pad 4100333 |
| Quick Disconnect | Drive core adapters 160CW1 and 160CW2, casing adapter 150DE1 | Q.D. Release Complete (25AN1), core adapter 160CY1 |
| Shafts and Heads | Universal inventory. Likely reusable across both models (confirm fitment before ordering). | |
4-Stroke Engine and Fuel
Use straight unleaded fuel only. Never add 2-cycle oil to the gas tank, this is a 4-stroke engine with a separate oil sump. Follow the Honda GXH50 owner's manual for oil changes, spark plug, and air filter service. Always remove the spark plug wire and place the switch in the off position before assembly or accessory changes.
2-Stroke Engine and Fuel
Always run pre-mixed fuel at the ratio specified on your 2-cycle oil bottle (commonly 50:1 with modern synthetic oils). Mix only what you will burn within 30 days. Drain the tank and run the carburetor dry before long-term storage. Stale or unmixed fuel is the leading cause of seized 2-cycle top ends.
Flexible Shaft (Both Models)
Re-lubricate the inner core every 50 hours of operation. Remove the core on a clean surface, wipe down, and apply a 1/16 inch coating of high-quality lithium grease before reinstalling. Do not over-grease. Replace the core if you see kinking, dry spots, or wear on the square-drive ends.
Quick Disconnect and Safety
Keep the square drive on the quick disconnect free of dried concrete. Inspect the spring pin for wear before each use, the shaft must lock with no rotational play. Apply adhesive sealant to the head-end shaft threads on every install for a water-tight seal. A worn QD will eject the shaft under load, replace before that happens.
Need Help Identifying a PRO50 Part?
Share your model designation (PRO50 2-Stroke or PRO50 4-Stroke), serial number, and the part you are replacing. If your unit has a Walbro carburetor, send the WYK-104 or WYK-144 stamping. Our parts team confirms exact fitment before every order ships.
Frequently Asked Questions
Match the Ref. # on the diagram to the row in the parts list at the right. Click a part name to see details, price, and add it to cart.
Confirm your model/series and serial number range on the product page. Many manufacturers have serial breaks, when in doubt, share your model and serial with us and we’ll verify fit.
The Ref. # points to the callout on the drawing. Qty shows how many of that item your machine uses. Parts are sold individually unless noted as a kit.
Yes, we supply genuine OEM parts for all our brands. If a part has an approved replacement, we ship the latest superseded revision
Manufacturers often supersede numbers. Our pages list the current orderable number and show older numbers in the description when available. Your old number will cross-reference to the correct part.
Yes. Some items are not pictured or are shared with other assemblies. Send us the model, serial, and a description (or photo) and we’ll locate it.
Yes. DanseUSA passes the manufacturer’s warranty to you. Coverage applies to defects in materials and workmanship under normal use for 30 days from the purchase date, in line with the manufacturer’s warranty policy. Terms can vary by brand; the product page reflects the applicable policy. If a claim is needed, we’ll help coordinate with the manufacturer.
Yes, most new, uninstalled items can be returned under our standard policy. Please see our Returns & Refunds Policy for eligibility, timeframes, and any exceptions.