WILLIAMS 435 SportJet

(Rotax 903 Engine)

Technical Guide, Maintenance and Spare Parts

The Williams SportJet 435 is a jet-propelled sport tender designed primarily for yachts 20 meters and larger.

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

An important feature of the SportJet 435 is that it has existed with several Rotax engines depending on the year and version. The Rotax ACE 903 can be found on the Standard version, the Rotax 1503 on certain Sport versions, and then the Rotax ACE 1630 on newer Sport versions.

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

This guide provides an overview of the different versions of the Williams SportJet 435, according to their engines, but it is dedicated to the model equipped with the Rotax ACE 903 engine. The detailed specifications, maintenance table, parts selection and FAQ below 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
• Turbine block parts
• Other

The different 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 production:

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

It is the version to choose for owners looking primarily for a comfortable and versatile tender, while retaining good performance.

See our Rotax ACE 903 engine guide.

SportJet 435 Sport – Rotax 1503

Some Sport versions of the Williams SportJet 435 have been equipped with the Rotax 1503 engine. This larger displacement engine provides more power and torque, notably for water activities and uses requiring better acceleration.

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

See our Rotax 1503 engine guide.

SportJet 435 Sport – Rotax ACE 1630

On newer versions, notably from 2021, 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 to know which version of SportJet 435 you own?

Before ordering a part, check:

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

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

Technical specifications of the Williams SportJet 435 Standard

• Overall length: 4.35 m.
• 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.
• Capacity: 7 people.
• Fuel tank: 60 liters.
• Maximum speed: up to 64 km/h (40 mph).
• Recommended yacht: 20 m and larger.

Specifications may vary depending on the year, engine, equipment and configuration of the tender.

Some maintenance parts may be common to other ACE 903 engine tenders when the OEM references and fitments match. The same engine family does not guarantee the interchangeability of all components.

How often to maintain the WILLIAMS SportJet 435 Standard?

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

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

For the SportJet 435 Standard engine flushing, follow the WILLIAMS and Rotax procedure corresponding to your tender. After use in salt water, flushing and 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 of the WILLIAMS SportJet 435 Standard – ACE 903

This selection is based on the SportJet 435 Standard applications with the ACE 903 engine declared in our sheets. OEM references serve as a starting point to determine the corresponding aftermarket part number, without designating original parts. Check the year, reference and fitment before ordering; do not apply this selection to the Sport 1503 or 1630 versions. Click on a "Buy" thumbnail to add one unit of the product to the cart and access the cart. If a choice is necessary, the "Choose the version" thumbnail opens the sheet. Names and references always open the product sheets.

The iNR connector concerns only the tenders equipped with this option. For the fuel pump, the sheet indicates SportJet applications from 2019; also compare the dimensions and fitment.

Buy	Part	OEM Reference	Function
	Oil filter, pack of 4	420956123	ACE 903 engine oil filtration. O-ring not included.
	NGK CR8EB compatible spark plugs, pack of 3	5297925 / CR8EB	Standard ACE 903 version ignition. Generic CR8EB compatible alternative.
	Ignition Coil	420666142	Ignition spark production.
	35 A / 12 V Relay, per unit	278002822 / 278003828 ; Williams 02-0860	Electrical circuit switching.
	35 A / 12 V Relay, pack of 5	278002822 / 278003828 ; Williams 02-0860	Switching electrical circuits; workshop conditioning.
	Starter Solenoid Relay	278000513 / 278002347 / 278001802 / 278001766 ; Williams 02-1108	Switching the starter power supply.
	12 V Power Relay	278003012 ; Williams 06-0521	Electrical switching. Compare with the original installation.
	Electric Starter	420892426 / 420893830 ; Williams 02-1430	Engine drive at startup.
	Voltage Regulator / Rectifier	710001103 / 0460375 ; Williams 02-1013	Voltage regulation and battery charging.
	Fuel Pump	275500996 / 275500850 ; Williams 06-0700	Fuel supply. Applications declared since 2019; dimensions and installation to be checked.
	Fuel Pump Strainer, Pack of 2	270600113	Fuel pre-filtration.
	Throttle Body	420893144 / 420893141 ; Williams 02-1180	Air intake management. Check the model year limits indicated in the data sheet.
	Crankshaft Position Sensor	420966575 / 420966570	Crankshaft position reading for engine management.
	Camshaft Position Sensor	420664045 ; Williams 02-1089	Camshaft position reading.
	Coolant Temperature Sensor	278002895 / 278001016 ; Williams 02-1065	Cooling system temperature monitoring.
	O2 Lambda Sensor	707600872	Oxygen measurement in exhaust gases.
	Crankshaft Bearing Kit	420450165 / 420850220 / 420450080	Sealing for the Standard version ACE 903 engine.
	iNR Connector Housing, Single	278002880	Wiring repair, only on tenders equipped with the iNR option. Compare the generation and original connector.

Common Problems with the WILLIAMS SportJet 435 Standard

The following symptoms can have several causes. These clues guide checks but do not constitute a diagnosis or an indication of automatic part replacement. Work on fuel, moving parts, and electrical circuits must be carried out safely, according to the manual, and by a professional when necessary. (FMT)

• The engine does not start: check the battery voltage, electrical connections, battery disconnect switch, kill switch cable, fuses, relays, fuel supply, fuel pump, spark plugs, coils, and any fault codes. A battery capable of powering accessories may not provide sufficient voltage during starting.
• Engine misfires: ignition components, fuel supply, sensors, and electrical connections are among the clues to examine. A targeted check helps avoid random part replacement.
• The engine starts but lacks power: insufficient fuel supply, clogged filter, incorrect fuel pressure, faulty injector, spark plug, or coil, engine sensor, cooling, electronic limitation, or propulsion block. Reading fault codes can guide the diagnosis.
• Fault code displayed: the electronic system may report an anomaly and limit engine performance. A code indicates a detected fault, not necessarily a defective part.
• The engine overheats: check the water supply, cooling system, hoses, any obstructions, temperature sensors, and exhaust system. Stop the engine in case of a persistent alert and look for the cause before continuing use. After use in salt water, perform the flush according to the manufacturer's recommendations. See our article on engine overheating.
• The SportJet 435 Standard lacks thrust: the engine is not necessarily to blame. Have the intake screen, propulsion block, internal propeller, and forward / reverse system inspected. Sucked-in algae, ropes, plastic bags, or other debris can greatly 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 checks. (FMT)

How to identify the right part for your SportJet 435?

Send us a clear photo of the part, its OEM reference when visible, the model, year, and engine identification information. Be sure to specify the Standard or Sport version, the ACE 903, 1503, or ACE 1630 engine, and the presence of options such as iNR for the components concerned. 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 designs differ. 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 onboard comfort. See our Williams TurboJet 325 guide.

WILLIAMS SportJet 435 Standard: Frequently Asked Questions - FAQ

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

• What engine equips the Williams SportJet 435 Standard?

  The Standard version presented here is equipped with a BRP Rotax ACE 903 producing 90 HP. Other SportJet 435s exist with a Rotax 1503 Sport or Rotax 1630 engine: identify your version before 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 cm³.

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

  The Rotax ACE 903 engine in this version uses NGK CR8EB spark plugs. Always check the part number 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 meets the specifications recommended by BRP for the Rotax ACE 903 engine, namely BRP XPS 4T 5W-40. Follow your jet ski's maintenance recommendations. For the 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: should be carried out between 10 and 25 hours (oil change and oil filter replacement, hose and clamp checks, and general inspection). The following intervals: depend on the jet ski's hours and the date of the last service. The table provided above includes, among other things, servicing 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 propeller integrated into the turbine block.

• Can the SportJet 435 Standard be used for waterskiing?

  Yes, that is one of its strengths. Water sports (waterskiing, wakeboarding, towed tubing, etc.) are of course possible, including on this Standard model. That being said, a Sport model (Rotax 1503 or 1630) will be 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 the order of operations and water supply. Consult our Rotax engine flushing guide in addition to the manual. Do not automatically apply this procedure to the Sport versions.

• Why won't my SportJet 435 Standard start?

  A weak battery, a relay, fuse, kill switch, fuel pump, ignition, engine sensor, or electrical circuit problem may be the cause. A precise diagnosis is recommended before replacing a part. (FMT)