Choose the right donor for your build

Donor and propulsion options by kit

Start with Sitka’s options for your hull. The notes identify preferred packages, tighter fits and setups that need extra fabrication. Larger kits also have marine engine-and-pump or outboard-jet options.

Before buying, review the exact donor model and year, complete engine-and-pump package, intended load and installation plan with Sitka. Include the mounts, shaft, intake, exhaust, cooling and controls in that review.

Start with a complete donor

A donor is the jet ski whose engine, jet pump and selected supporting parts you reuse in the boat. A complete, running jet ski lets you check those parts together. Photograph the working system before dismantling it so you can identify the parts and connections your mini jet boat will need.

An engine-only purchase can still work, but list and price the missing pump, electronics, controls, exhaust and cooling components first. Keep the donor’s exact make, model, year and engine identification with that list.

For a Sitka build, review the donor with your chosen hull, passenger and gear load, and intended use before buying. The complete installation needs to fit the boat.

Compare donor types

Start with the options for your Sitka kit, then narrow your search to an exact donor model and year. Compare the complete systems, including their size, weight, controls and cooling needs. These engine-family descriptions help you understand the work involved in each approach.

Sea-Doo Spark specifications (PDF) · Yamaha TR-1 specifications · Sea-Doo supercharged-engine equipment (PDF)

Check the complete installation

• Measure the complete package. Include the intake, exhaust, waterbox (exhaust silencer), mounts, hoses and room to reach service items. An engine that fits between the stringers may still leave no room for its exhaust.
• Match the pump and intake. Identify the pump housing, impeller, nozzle, intake and adapter arrangement. Confirm how the shaft support and seals attach to the hull.
• Check the shaft seals and supports. Identify the bearing carrier and seal type, its condition, installation dimensions and service access. An adapter’s bolt pattern alone does not establish shaft or seal compatibility.
• Set the shaft layout before ordering modifications. Review engine position, coupling, bearing carrier, shaft length and alignment together.
• Check the controls from helm to stern. Measure the steering and throttle routes, cable travel, and any reverse or trim arrangement.

An engine name does not identify the pump. Yamaha’s published specifications pair the TR-1 SuperJet with a 144 mm pump and the TR-1 High Output VX with a 155 mm pump. Record the donor model and year as well as the engine name.

Yamaha SuperJet specifications · Yamaha VX specifications

Inspect the donor before buying

Get the operator’s guide for running, flushing and maintenance instructions, and the service or workshop manual for diagnostics, wiring and repair specifications. Use the information for the exact model and year to work through the checks below. If you lack the tools or experience for a check, or are unsure how to interpret the results, ask a jet ski technician to help with that inspection:

1. What is the history? Ask about hours, storage, saltwater use, overheating, water ingestion, rebuilds and modifications. Request receipts and service records.
2. Can the seller demonstrate it running? Arrange a demonstration under the conditions allowed by its operator’s guide, and note starting behavior, warnings, unusual noise and leaks. A brief start alone does not establish engine or pump condition. Out-of-water running and flushing have model-specific limits; get the exact procedure before attempting either.
3. How healthy is the engine? Compare compression or other appropriate diagnostic results with that model’s service specifications. Keep the readings and any fault information with the inspection report.
4. What condition is the pump in? Inspect the impeller, wear surface, bearings, shaft and seals using the model’s service procedure. Include repair needs in your comparison.
5. Is the electrical package complete? Check the harness, connectors, engine controller, instruments and working key or security equipment where fitted. Photograph cut wires and missing components.
6. What needs replacing before installation? Get a written list and check parts availability before committing to the donor.

Keep the purchase paperwork, identification-label photos and inspection results together. A low purchase price is only useful once the missing parts and repair work are understood.

For Sea-Doo donors, find operating and flushing instructions by model and year in the BRP operator-guide library. Obtain the separate service manual for diagnostic and installation specifications.

Keep the useful parts together

Photograph connections and label parts before dismantling the donor. Keep these assemblies available until your installation plan is settled:

Inspect each part before reuse and confirm that it suits the new installation. Keep the original components for reference even when the boat needs a different tank, longer cables or revised mounting brackets.

Dismantle with the boat installation in mind

Use the service manual for the exact donor to plan disassembly, fluid handling and engine lifting. Before taking anything apart, record the running checks and photograph the complete installation.

1. Label both ends. Give each disconnected hose and electrical connector a matching label. Photograph its route and connection before removal; bag the fasteners with the part they secure.
2. Keep the matched equipment together. Store the engine electronics, display, working key, throttle, reverse and trim controls as one identified package. Retain brackets, clamps, seals and small fittings with their assemblies.
3. Mark each part’s next job. Separate parts intended for reuse, parts needing repair or replacement, and parts kept as references. A cable, airbox or fuel filler that worked in the ski may need a different arrangement in the boat.
4. Check before disposing of the shell. Reconcile the saved parts with your boat’s installation plan. Retain useful mounting and routing measurements, identification photos and purchase records.

Keep the labeled assemblies clean, dry and protected while the hull is being built.

Plan cooling and controls early

Know how the engine sheds heat

Raw-water cooling uses water drawn from outside the boat. A closed circuit circulates coolant and transfers its heat through a heat exchanger. Identify which arrangement your donor uses. For a closed-loop installation, include the heat exchanger, mounting space and plumbing in the plan. Check the exhaust cooling requirements separately: a closed-loop engine can still have a water-cooled exhaust.

The ride plate is the plate beneath the rear of the jet ski. If it also serves as a heat exchanger, removing the engine from the jet ski leaves that part of the cooling system behind. Plan a suitable heat exchanger and its connections as part of the conversion. Keep the engine and exhaust cooling routes clearly identified.

Keep electronic controls with the donor

For an electronically controlled throttle or reverse system, retain the original sensors, switches, connectors and associated equipment until the conversion plan is confirmed. Identify which components must be retained or adapted for the new helm.

Include the complete electronic reverse or trim system in the review where fitted. An actuator is the device that moves the reverse or trim mechanism. Its nozzle, sensors, controls and engine electronics may work together. Establish the integration plan before removing components or changing the wiring.

Map harness changes before cutting

A harness is the bundled wiring and connectors linking the engine’s electrical equipment. Identify it separately from the boat’s accessory circuits, such as lighting and the bilge pump. Record connector positions and wire identities from the donor’s wiring diagram; identical wire colors do not guarantee identical functions. Plan extensions along the actual route, including steering movement and room to disconnect components for service.

Keep the required sensors and interlocks functional. Check harness changes against the exact donor’s diagram, then test the controls and instruments before closing the loom or fitting interior panels.

Get a working key and record the security equipment

On Sea-Doo models equipped with D.E.S.S., the coded key must match the vehicle’s security system. Confirm that the supplied key works and retain its associated components; resolve missing-key or controller questions before dismantling.

Sea-Doo engine, exhaust and electronic-control documentation (PDF) · Sea-Doo coded-key documentation (PDF, page 59)

Mini jet boat build examples

A 3.3 m kit with a Yamaha WaveVenture 1100

A kit builder documented a 3.3 m aluminum hull kit powered by a 1996 Yamaha WaveVenture 1100. The installation needed an adapter for the shaft-bearing housing, a shortened driveshaft and changes to fit the exhaust. The original steering cable was also too short. Allow for adapters and controls in your parts list alongside the engine and pump.

Read the kit builder’s journal

A 10 ft aluminum boat with a Yamaha 701

A discussion of this Yamaha 701-powered, 10-foot aluminum boat describes improved performance after worn pump components were replaced. It also describes very little space between the exhaust pipe and the bulkhead. Check pump condition and exhaust clearance before planning engine upgrades.

Read the Yamaha 701 build discussion

Review your donor with Sitka

Send the listing and these details before buying your donor:

• Your Sitka hull model and selected options, intended passenger and gear load, and how you plan to use the boat.
• Donor make, model, year and engine identification, with clear label photos.
• Pump identification and photos of the intake, shaft support, coupling and mounts.
• Photos and measurements showing the engine, exhaust, waterbox and cooling equipment.
• The included electronics and controls, inspection results, and any missing or damaged parts.

Use the complete boat systems checklist to connect your donor inventory to the rest of the build.

Compare the donor price with the expected repairs, missing components and installation work. Review those items alongside the other costs of your build.