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Banjo introduced the M350 transfer-pump range on January 31, 2023, with a new flow design and tandem wet seal. The M350PH13W combines the 3-inch manifold pump with a 13 HP Honda engine; PhiBer’s listed package specifies the GX390 and excludes a battery.
The inlet plumbing makes a measurable difference to the manufacturer’s maximum-flow comparison. With flooded suction, Banjo lists 450 US GPM using a 3-inch suction line and 515 US GPM using a 4-inch line.
| M350PH13W detail | Specification |
|---|---|
| Pump ports | 3-inch manifold flanges |
| Construction | Polypropylene components, EPDM seals and stainless-steel hardware |
| Engine | 13 HP Honda; listed GX390 package without battery |
| Seal arrangement | Tandem wet seal with separate reservoir |
| Typical operating speed | 3,600 RPM |
| Occasional suspended solids | Up to ½ inch diameter, as specified by Banjo |
Why a 4-inch inlet can feed a 3-inch pump
The larger suction run supplies the pump with less restriction under the manufacturer’s comparison conditions. The 3-inch port remains at the pump, while the larger hose and adapters carry the upstream run.
| Flooded suction arrangement | Listed maximum flow |
|---|---|
| 3-inch suction | 450 US GPM |
| 4-inch suction | 515 US GPM |
The curve also shows flow falling as the required pressure rises. Its horizontal axis is flow and its vertical axis is pressure rise; the far-right endpoint describes a different duty from an operating point farther up the curve.
Banjo’s manual calls for airtight suction connections, a short inlet route and few bends. An air leak can interrupt priming even when liquid does not visibly leak outward from the joint.
For the 4-inch connection, M300400A adapts a 3-inch manifold flange to a 4-inch male cam connection; M300400BRB provides the 4-inch hose barb.
Pressure helps the tandem seal stay closed
In Banjo’s tandem arrangement, internal pump pressure acts in the same direction as the inner seal spring. The forces help hold that seal closed. The manufacturer’s illustration contrasts that geometry with an opposed arrangement that can be pushed open by internal pressure.
The separate reservoir supplies coolant and lubrication to the seals. The instruction manual specifies a 50/50 antifreeze-and-water mixture, a coolant check every eight operating hours or at refuelling, and replacement every 500 hours or annually.
The wet seal provides protection during incidental interruptions in flow. The operating manual prohibits intentional dry running; the pump casing still needs its initial liquid fill for startup and priming.
Service parts in the original drawing
| Catalogue drawing item | Banjo part | Component |
|---|---|---|
| 12 | 35002 | Diffuser |
| 14 | 35005 | Check valve |
| 15 | 35073 | 5-vane impeller |
| 17 | 35201 | Wet-seal reservoir |
| Separate kit | 35000 | M350 repair kit; contents listed separately |
These callouts belong to the cited 2026 catalogue drawing. The adjacent parts list establishes the orderable numbers and the components included in a repair kit.
Engine package or pump only
M350PH13W includes the Honda engine. M350POW supplies the pump-only version for a 1-inch-shaft gas engine. The existing shaft and mounting establish the fit when an engine is being retained.
The M350 priming guide follows the suction path and initial casing fill. The manufacturer’s manual also excludes flammable-liquid service.
Sources and product information
- Banjo 2026 catalogue: printed page 128 for the Honda model and page 131 for the exploded parts list.
- Banjo M350 sales sheet, Rev. 0723: performance comparison, wet-seal illustration and flow curve. Manufacturer document hosted by Dual Pumps.
- Banjo M350 instruction manual, Rev. 1122: operation, maintenance and troubleshooting. Manufacturer document hosted by Dual Pumps; use the instructions supplied with your unit if they differ.
- Banjo's M350 launch explanation: how the tandem-seal pressure direction works.
Technical review: November 4, 2026.
