WILLIAMS 435 SportJet

(Rotax 903 engine)

Technical guide, maintenance and spare parts

The Williams SportJet 435 is a jet-propelled sports tender intended primarily for yachts of 20 meters and over.

With its 4.35m length and a capacity of up to 7 people, it offers more space than the SportJet 345 and 395 while maintaining the performance and handling characteristic of the SportJet range.

A significant particularity of the SportJet 435 is that it existed with several Rotax engines depending on the year and version. Notably, we find the Rotax ACE 903 on the Standard version, the Rotax 1503 on certain Sport versions, and then the Rotax ACE 1630 on more recent Sport versions.

It is therefore particularly important to know the exact year and engine of the tender before ordering an engine part.

This guide provides an overview of the various versions of the Williams SportJet 435, according to their engines, but is dedicated to the model equipped with the Rotax ACE 903 engine. The detailed specifications, maintenance schedule, parts selection, and FAQ below therefore concern the Standard version with the 90 HP Rotax ACE 903 engine.

Find parts for your WILLIAMS SportJet 435

• Engine parts
• Fuel system
• Ignition
• Sensors
• Electrical parts
• Cooling
• Oil and filters
• Gaskets and seals
• Jet pump parts
• Others

The various versions of the Williams SportJet 435

This article is dedicated to the SportJet 435 Standard model (with Rotax ACE 903 engine).

That said, it is important to know that this SportJet 435 has been offered with different engines during its commercial lifespan:

• SportJet 435 Standard – Rotax ACE 903 (described in this article)

• SportJet 435 Sport – Rotax 1503

• SportJet 435 Sport – Rotax ACE 1630

SportJet 435 Standard – Rotax ACE 903 (described in this article)

The Standard version is equipped with the 90 HP BRP Rotax ACE 903. This three-cylinder four-stroke engine is also used on several other Williams Jet Tenders, notably the TurboJet 285 and 325 as well as the SportJet 345 and 395.

This is the preferred version for owners looking primarily for a comfortable and versatile tender while maintaining good performance.

See our Rotax ACE 903 engine guide.

SportJet 435 Sport – Rotax 1503

Certain Sport versions of the Williams SportJet 435 were equipped with the Rotax 1503 engine. This higher-displacement engine provides more power and torque, particularly for water sports and uses requiring better acceleration.

The engine parts for this version are different from those of the Rotax ACE 903. Some part numbers may be common, but this must be verified part by part.

See our Rotax 1503 engine guide.

SportJet 435 Sport – Rotax ACE 1630

On more recent versions, particularly from 2021 onwards, the SportJet 435 Sport can be equipped with the Rotax ACE 1630. This generation is gradually replacing the older Sport engines based on the Rotax 1503; although very similar, always confirm the engine actually installed without relying solely on the year.

The Rotax 1630 has many specific parts: it is therefore essential not to rely solely on the "SportJet 435" model to identify a part.

See our Rotax 1630 engine guide.

How do I know which version of the SportJet 435 I have?

Before ordering a part, verify:

• the tender's year of manufacture;
• the exact engine model (see engine plate or tender certificate of conformity);
• the indicated power;
• the tender or engine serial number.
• Compare your engine with the photos of the engine compartments (see above)

Two Williams SportJet 435s can look very similar from the outside while using completely different engines and mechanical parts.

Technical specifications of the Williams SportJet 435 Standard

• Overall length: 4.35 m.
• Beam (width): 1.94 m.
• Dry weight: 446 kg.
• Height: 1.06 m.
• Height in low configuration: 0.97 m.
• Engine: BRP Rotax ACE 903.
• Power: 90 HP.
• Propulsion: Jet pump.
• Capacity: 7 people.
• Fuel tank: 60 liters.
• Maximum speed: up to 64 km/h (40 mph).
• Recommended yacht size: 20 m and over.

Specifications may vary according to year, engine, equipment, and tender configuration.

Some maintenance parts may be common to other tenders with the ACE 903 engine when OEM part numbers and assemblies match. Being in the same engine family does not guarantee the interchangeability of all components.

How often should the WILLIAMS SportJet 435 Standard be serviced?

The table below reflects the schedule retained for this article at your request, for the Standard version with the ACE 903 engine. Verify its application to your model year and configuration in the WILLIAMS documentation. It does not constitute the maintenance schedule for Sport versions with the 1503 or 1630 engines.

In a marine environment, regularly monitor the engine oil, oil filter, spark plugs, fuel circuit, cooling, battery, electrical connections, anti-corrosion protection, steering, propulsion unit, and anodes.

For flushing the engine of the SportJet 435 Standard, follow the WILLIAMS and Rotax procedure corresponding to your tender. After use in saltwater, flushing and anti-corrosion protection contribute to the longevity of the engine and its components. Our engine flushing guide complements these recommendations without replacing the model manual.

Common parts for the WILLIAMS SportJet 435 Standard – ACE 903

This selection is based on the SportJet 435 Standard applications with ACE 903 engine stated in our files. OEM part numbers serve as an entry point to determine the corresponding aftermarket part, without designating genuine parts. Check the model year, part number, and assembly before ordering; do not transpose this selection to the Sport 1503 or 1630 versions.

The iNR connector concerns only tenders equipped with this option. Regarding the fuel pump, the file indicates SportJet applications since 2019; also compare dimensions and assembly.

Common problems with the WILLIAMS SportJet 435 Standard

The following symptoms may have several causes. These leads are intended to guide checks but do not constitute a diagnosis or an indication for automatic part replacement. Interventions on the fuel system, moving parts, and electrical circuits must be performed safely, according to the manual and by a professional when necessary. (FMT)

• Engine does not start: check battery voltage, electrical connections, battery disconnect switch, safety lanyard, fuses, relays, fuel supply, fuel pump, spark plugs, ignition coils, and any fault codes. A battery capable of powering accessories may not provide sufficient voltage during cranking.
• Engine misfire: ignition components, fuel supply, sensors, and electrical connections are among the areas to examine. Targeted checking helps avoid random part replacement.
• Engine starts but lacks power: insufficient fuel supply, clogged filter, incorrect fuel pressure, faulty injector, spark plug or ignition coil, engine sensor, cooling issues, electronic limitation, or propulsion unit issues. Reading fault codes can guide the diagnosis.
• Fault code display: the electronic system may signal an anomaly and limit engine performance. A code indicates a detected fault, not necessarily a defective part.
• Engine overheating: check water supply, cooling circuit, hoses, potential obstructions, temperature sensors, and the exhaust system. Stop the engine in case of persistent warnings and find the cause before continuing use. After use in saltwater, flush the engine according to the manufacturer's recommendations. See our article on engine overheating.
• SportJet 435 Standard lacks thrust: the engine is not necessarily the cause. Have the intake grate, propulsion unit, internal impeller, and forward/reverse system inspected. Algae, ropes, plastic bags, or other ingested debris can significantly reduce performance. Stop the engine and prevent any restart before inspection; do not attempt to clear the water intake while the engine is running.

Consult our Rotax fault code guide to identify recorded faults and guide your checks. (FMT)

How to identify the right part for your SportJet 435?

Send us a clear photo of the part, its OEM reference number when visible, the model, the model year, and engine identification information. It is essential to specify the Standard or Sport version, the ACE 903, 1503, or ACE 1630 engine, and the presence of options such as iNR for relevant components. We can help you identify a suitable replacement part.

You can also use our tool: Identify my part from a photo.

SportJet 435 Standard or TurboJet 325?

The Williams SportJet 435 Standard and the TurboJet 325 described here both use the 90 HP Rotax ACE 903, but their design differs. This comparison does not concern the Sport versions of the 435.

The TurboJet 325 prioritizes compact format and performance, while the SportJet 435 Standard offers more space for water sports and on-board comfort. Consult our Williams TurboJet 325 guide.

WILLIAMS SportJet 435 Standard: FAQ

The answers below apply only to the Standard version with the ACE 903 engine. For Sport 1503 and 1630 versions, consult the corresponding engine guide and the documentation specific to the tender.

• Which engine powers the Williams SportJet 435 Standard?

  The Standard version presented here is equipped with a BRP Rotax ACE 903 engine producing 90 HP. Other SportJet 435 models exist with a Sport Rotax 1503 or Rotax 1630 engine: identify your version before placing any order.

• What is the engine displacement of the SportJet 435 Standard?

  The Rotax ACE 903 is a three-cylinder, four-stroke engine of approximately 899 cc.

• What spark plugs does the Williams SportJet 435 Standard use?

  The Rotax ACE 903 engine in this version uses NGK CR8EB type spark plugs. Always check the reference corresponding to your engine before replacement. Our set of 3 CR8EB-compatible spark plugs is a generic alternative. These spark plugs are different for the Sport 1503 or 1630 versions.

• What oil should be used in a Williams SportJet 435 Standard?

  Use oil that complies with the specifications recommended by BRP for the Rotax ACE 903 engine, namely, BRP XPS 4T 5W-40. Follow your tender's maintenance recommendations. For Sport versions, consult the Rotax 1503 and Rotax 1630 guides.

• How often should a Williams SportJet 435 Standard be serviced?

  First service after break-in: to be performed between 10 and 25 hours (oil change and oil filter replacement, hose and clamp checks, and general inspection). Subsequent intervals: depend on the tender's engine hours and the date of the last service. The table provided above includes interventions at 50, 100, and 200 hours, or according to the corresponding calendar intervals.

• Does the SportJet 435 Standard have a propeller?

  It does not have a conventional external propeller. It uses jet propulsion, with an internal impeller integrated into the turbine unit.

• Can the SportJet 435 Standard be used for water skiing?

  Yes, that is actually one of its strengths. Water activities (water skiing, wakeboarding, towable tubes, etc.) are of course possible, including on this Standard model. That said, a Sport model (Rotax 1503 or 1630) is preferred for reasons of power and long-term engine preservation.

• How do you flush a Williams SportJet 435 Standard?

  Follow the WILLIAMS and Rotax instructions specific to your ACE 903 engine and model year, especially regarding the sequence of operations and water supply. Consult our Rotax engine flushing guide as a supplement to the manual. Do not automatically apply this procedure to Sport versions.

• Why won't my SportJet 435 Standard start?

  A weak battery, a relay issue, a blown fuse, a safety lanyard problem, a faulty fuel pump, ignition, engine sensor, or electrical circuit issue could be the cause. An accurate diagnosis is recommended before replacing any part. (FMT)