WILLIAMS 435 SportJet Sport
(Rotax 1503 Engine)
Technical Guide, Maintenance and Spare Parts
The Williams SportJet 435 Sport equipped with the BRP Rotax 1503 4-TEC 150 HP engine is the high-performance version of the SportJet 435 from this generation.
Thanks to its three-cylinder 1,494 cm³ engine, this version offers superior acceleration and performance compared to the SportJet 435 Standard equipped with the 90 HP Rotax ACE 903.
With a stated top speed of approximately 84 km/h (52 mph), the SportJet 435 Sport 1503 is particularly suited for water sports while retaining its primary function as a yacht tender.
The SportJet 435 model has been available with several engine options depending on the year and version. This guide concerns the 150 HP naturally aspirated Rotax 1503 4-TEC configuration, not the Standard ACE 903 or the Sport ACE 1630 versions. Identify the year, power, and engine serial number before ordering any parts.
Find Parts for Your WILLIAMS SportJet 435 Sport – Rotax 1503
- Engine parts
- Fuel system
- Ignition
- Sensors
- Electrical parts
- Cooling
- Oil and filters
- Gaskets and seals
- Impeller block parts
- Other
The Different Versions of the Williams SportJet 435
This article is dedicated to the SportJet 435 Sport with Rotax 1503 engine. The three configurations below help distinguish the engine options, but do not replace checking the engine plate.
- SportJet 435 Sport – Rotax 1503 (described in this article)
- SportJet 435 Standard – Rotax ACE 903
- SportJet 435 Sport – Rotax ACE 1630
SportJet 435 Sport – Rotax 1503 (described in this article)
This generation of the SportJet 435 Sport is equipped with the BRP Rotax 1503 4-TEC 150 HP engine, a 1,494 cm³ four-stroke three-cylinder engine. In this Williams configuration, it is a naturally aspirated version, without a compressor.
This engine option provides more power and torque than the 90 HP Standard ACE 903, especially for water activities and uses requiring better acceleration. Engine parts differ; some references may be common, but this must be checked part by part.
See our Rotax 1503 engine guide.
SportJet 435 Standard – Rotax ACE 903
The Standard version is equipped with the BRP Rotax ACE 903 90 HP engine. This four-stroke three-cylinder engine is also used on the TurboJet 285 and 325, as well as the SportJet 345 and 395 described in our guides.
Find its specifications and parts in our article on the Williams 435 Standard with Rotax ACE 903 engine.
SportJet 435 Sport – Rotax ACE 1630
On newer versions, notably from 2021 depending on the configuration, the SportJet 435 Sport can be equipped with the Rotax ACE 1630. Always confirm the engine actually installed without relying solely on the year. Many parts are specific: the "SportJet 435" designation is not enough to identify a part.
See our Rotax 1630 engine guide.
How to know which version of SportJet 435 you own?
Check the year of manufacture, the engine model on the plate or the certificate of conformity, the power, and the serial number of the tender or engine. Photos can help identify it, but do not replace engine identification. Two SportJet 435s that look similar may use different mechanical parts.
Technical Specifications of the Williams SportJet 435 Sport – Rotax 1503
- Overall length: 4.35 m.
- Width: 1.93 m.
- Height: 1.04 m.
- Draft under load: 0.36 m.
- Dry weight: 480 kg.
- Engine: BRP Rotax 1503 4-TEC.
- Displacement: 1,494 cm³.
- Power: 150 HP.
- Propulsion: jet.
- Capacity: 7 people.
- Fuel tank: 60 liters.
- Top speed: up to 84 km/h (52 mph).
- Maximum load: 633 kg.
- Tube compartments: 5.
- CE category: C.
- Recommended yacht: approximately 20 m and larger.
Specifications may vary slightly depending on the year of manufacture, equipment, and tender configuration.
Maintenance Schedule – Williams SportJet 435 Sport / Rotax 1503
The Williams maintenance program provided for this article is based mainly on three intervals: 50 hours or 1 year, 100 hours or 1 year, then 200 hours or 2 years. For operations directly related to the Rotax 1503 engine, also consult the corresponding engine manual. A dash indicates that no operation is specified in the table box, not a general exemption from maintenance.
| Item | 50 h / 1 year | 100 h / 1 year | 200 h / 2 years |
|---|---|---|---|
| Engine oil and filter | Replace | Replace | — |
| Rubber engine mounts | Inspect | Inspect | — |
| Engine anti-corrosion protection | Lubricate regularly* | Lubricate regularly* | — |
| Drive shaft sleeve / seal | — | — | Replace** |
| Exhaust system | Inspect | Inspect / clean | — |
| Exhaust flushing | Clean regularly*** | Clean regularly*** | — |
| Cooling hoses and fittings | Inspect | Inspect | — |
| Coolant | Inspect | Inspect | Replace |
| Throttle body | Inspect | Inspect | — |
| Fuel circuit and lines | Inspect | Inspect | — |
| Engine fault codes | Inspect | Inspect | — |
| Air filter | Inspect / replace if necessary | — | — |
| Spark plugs | Inspect | Inspect | Replace |
| Ignition coils | Inspect | Inspect | Inspect |
| Electrical connections | Inspect | Inspect | Inspect |
| Engine stop switch | Inspect | Inspect | Inspect |
| Steering cable and connection | Inspect | Inspect | — |
| Steering nozzle rings | Inspect | Inspect | — |
| Carbon ring / shaft boot | Inspect | Inspect | — |
| Thrust control and cables | Inspect | Inspect | — |
| Reverse bucket / rear door | Lubricate | Lubricate | — |
| Impeller shaft / PTO splines | Inspect / lubricate | — | — |
| Shaft seal, sleeve and O-ring | Inspect | — | Replace |
| Impeller and wear ring | Inspect | Inspect | — |
| Sacrificial anode | Check regularly**** | Check regularly**** | Check regularly**** |
| Intake screen / plate | Inspect | — | — |
* When used in salt water, protect the metal components of the engine compartment every 10 hours of use.
** The drive shaft sleeve and seal must be replaced at 200 hours, regardless of the number of years.
*** The exhaust system must be flushed daily after use in salt water or dirty water.
**** The sacrificial anode must be checked every month, and every two weeks in salt water. It must be replaced when necessary.
Important points for use in salt water
A SportJet used as a yacht tender is exposed to seawater. Corrosion prevention is therefore particularly important. After use, pay special attention to the following elements, according to the manufacturer's procedures:
- flushing the circuit;
- flushing the propulsion block;
- checking the anode;
- cleaning the engine compartment;
- anti-corrosion treatment of metal components;
- checking electrical connections;
- checking the impeller and intake screen.
Consult our engine flushing guide in addition to the WILLIAMS and Rotax manuals specific to your configuration.
Common parts for the WILLIAMS SportJet 435 Sport – Rotax 1503
The OEM references in this selection are used to identify replaced parts; they do not automatically indicate original parts. The two oil filters with reference 420956744 below are common to the 1503 and 1630 engines. Click on a "Buy" thumbnail to add one unit of the product to the cart and access the cart. If the batch or version requires a choice, the "Choose the version" thumbnail opens the product sheet. The names and references retain their links to the product sheets.
The iNR connector only concerns tenders equipped with this option. For the cylinder head, check the entire set of valves, ports, keys, springs, and valve seats before choosing a variant.
| Buy | Part | OEM Reference | Function |
|---|---|---|---|
 |
1503 4-TEC Head Gasket | 420641110 / 420950770 | Block / cylinder head sealing. |
 |
Valve Cover Gasket | 290950820 / 420950820 | Valve cover sealing. |
 |
4-TEC Timing Chain | 420898042 | Timing synchronization; |
 |
1503 Oil Pump Bellows | 420832648 | Oil circuit |
 |
1503 Connecting Rod Bearing Kit | Not specified | Bottom end rebuild; standard or repair +0.50 mm size to be chosen after professional measurements. |
 |
1503 Intake / Exhaust Valve | 420254682 ; 420254293 / 420254298 | Targeted replacement; intake, exhaust or pair, geometry and seats to be compared. |
 |
Kit 12 single-seat valves | 420254682 / 420253163 | Cylinder rebuild only if the distribution assembly uses the corresponding single-seat configuration. |
 |
Kit 12 triple-seat valves | 420254298 / 420254682 | Cylinder rebuild; triple-seat to be confirmed. Do not automatically substitute for a single-seat kit. |
 |
1503 Valve Stem Seals | 420630200 / 420630202 | Sealing around the valve stems; set of 6 or 12 depending on the variant. |
 |
1503 4-TEC Magneto Stator | 420889721 / 420889720 / 290889720 | Electrical production; Sea-Doo 2002–2017 applications listed, Williams mounting and connector to be confirmed. |
 |
1503 Complete Engine Gasket Kit | Not specified | Sealing during an engine rebuild; BLACK / RED versions and exact contents to be checked for your configuration. |
 |
4-TEC Forged Connecting Rod | 420917516 | Transmission of the piston's effort to the crankshaft; by the unit or by 3, reference and dimensions to be confirmed. |
 |
Connecting Rod and Crankshaft Bearings | 420933456 / 420933466 / 420933523 | Bottom end rebuild; variants and STD / repair sizes to be determined by measurement, according to the bearing surfaces concerned. |
 |
Intake Air Temperature Sensor | 420222427 / 420222423 | Air temperature measurement for engine management; reference and connection to be compared. |
| Buy | Part | OEM Reference | Function |
|---|---|---|---|
 |
Rotax 1503 complete piston kit, STD or +0.50 mm | 420890244 | 3-cylinder kit with pistons, rings, pins and circlips |
 |
WSM 010-862K piston kit, STD size | 420890244 / 420892735 ; WSM 010-862K | Piston, rings, pin and circlips |
Common problems with the WILLIAMS SportJet 435 Sport – Rotax 1503
The following symptoms may have several causes. These clues help guide checks, but do not replace a diagnosis or automatically justify replacing a part. Work on fuel, electrical systems and moving parts must be carried out safely, according to the manual and by a professional when necessary. (FMT)
- The engine does not start: battery, electrical connections, battery cut-off switch, kill cord, fuses, relays, fuel supply, spark plugs, coils or sensors. A battery capable of powering accessories may not provide sufficient voltage during starting.
- Engine misfires: methodically check the ignition, fuel supply, sensors and connections before replacing a part.
- Lack of power: spark plugs, coils, fuel supply, injectors, sensor, ECU fault, cooling or propulsion unit may be affected. This 150 HP configuration is naturally aspirated: do not look for a supercharger failure as on a turbocharged engine.
- Fault code displayed: the code indicates a detected anomaly, but does not necessarily identify a defective part. Check the fault and the checks provided for the installed engine.
- The engine overheats: check the water supply, cooling, hoses, obstructions and exhaust according to the documentation. Stop the engine in case of a persistent alert. See our article on engine overheating.
- The engine runs but thrust decreases: an obstruction of the water intake, debris, an internal propeller or a damaged wear ring may be the cause. Stop the engine and prevent any restart before inspection; never attempt to clear the engine water intake while the engine is running.
See our Rotax fault code guide to guide your checks. (FMT)
How to identify the right part for your SportJet 435 Sport 1503?
Send us a clear photo, the visible OEM reference, the model, year and engine serial number. Specify the 150 HP Rotax 1503 engine and the presence of the iNR option for the components concerned. Do not rely solely on the SportJet 435 designation.
Identify my part from a photo.
SportJet 435 Sport Rotax 1503 or Standard Rotax ACE 903?
The two configurations compared below have a capacity of 7 people and a 60-liter tank, but their engines and performance differ. The data concerns the described versions and may vary depending on the year and equipment.
| Feature | 435 Sport – Rotax 1503 | 435 Standard – Rotax ACE 903 |
|---|---|---|
| Length | 4.35 m | 4.35 m |
| Width | 1.94 m | 1.94 m |
| Height | 1.06 m | 1.06 m |
| Dry weight | 480 kg | 446 kg |
| Engine | BRP Rotax 1503 4-TEC | BRP Rotax ACE 903 |
| Power | 150 HP | 90 HP |
| Capacity | 7 people | 7 people |
| Tank | 60 liters | 60 liters |
| Advertised maximum speed | 84 km/h (52 mph) | 64 km/h (40 mph) |
| Recommended yacht | About 20 m and up | 20 m and up |
The 150 HP Sport 1503 offers superior acceleration and maximum speed, particularly interesting for water sports. The Standard ACE 903 90 HP remains another configuration of the same model, with its own parts and features. See our Williams SportJet 435 Standard guide.
WILLIAMS 435 SportJet (Rotax 1503): frequently asked questions - FAQ
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What engine is fitted to the Williams SportJet 435 Sport?
This generation of the SportJet 435 Sport is equipped with the BRP Rotax 1503 4-TEC, a three-cylinder four-stroke engine of 1,494 cm³ developing 150 HP.
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What is the difference between the SportJet 435 Standard and the SportJet 435 Sport?
The Standard of this generation uses the 90 HP Rotax ACE 903, while the Sport version described uses the 150 HP Rotax 1503. The Sport version offers significantly superior acceleration and maximum speed.
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What is the maximum speed of the SportJet 435 Sport 1503?
The advertised maximum speed for the 150 HP version can reach about 84 km/h (52 mph), depending on the configuration and operating conditions.
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What is the displacement of the Rotax 1503?
The Rotax 1503 described has a displacement of 1,494 cm³ and a three-cylinder four-stroke architecture.
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How many people can a SportJet 435 carry?
The Williams SportJet 435 described can accommodate up to 7 people. Respect the capacity and load limits of your tender.
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What is the tank capacity?
The tank capacity of the SportJet 435 Sport is 60 liters.
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What is the weight of the SportJet 435 Sport 1503?
The indicated dry weight for this version is about 480 kg, with possible variations depending on the year and equipment.
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Is the SportJet 435 Sport 1503 equipped with a supercharger?
No. In this Williams configuration of 150 HP, the Rotax 1503 is a naturally aspirated version.
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What spark plugs to use on a SportJet 435 Rotax 1503?
The recommended spark plugs are NGK DCPR8E. Our adaptable spark plugs DCPR8E compatible spark plug are perfectly suited for the Williams 435 Sport with a 1503 engine. NB: do not confuse it with the CR8EB of the Standard ACE 903.
- When to perform the Rotax 1503 oil change?First service after break-in: to be carried out between 10 and 25 hours (oil change and oil filter replacement, hose and clamp checks, and general inspection). The maintenance schedule (see above) then provides for the replacement of the engine oil and oil filter at 50 hours or 1 year, then every 100 hours or 1 year. Also consult the corresponding user manual.
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When to replace the spark plugs?
The provided schedule provides for their inspection at the 50-hour and 100-hour intervals, then their replacement at 200 hours or 2 years.
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Should the SportJet 435 be rinsed after use at sea?
Yes. Be sure to rinse after use in salt water or dirty water. Corrosion protection is particularly important in marine environments. Follow the WILLIAMS and Rotax procedure; see our rinsing guide in addition to the manual.
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Why does my SportJet 435 1503 lack power?
A loss of power may notably come from the following elements:
- spark plugs or coils;
- fuel supply;
- injectors;
- engine sensor;
- fault recorded in the ECU;
- water intake obstruction;
- impeller or wear ring;
- cooling problem.
Reading the fault codes and a methodical diagnosis are recommended before replacing parts. (FMT)
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Where to find parts for a Williams SportJet 435 Rotax 1503?
Rotax Tender Parts offers maintenance parts and components whose applications are specified in the data sheets. Browse the table in this article and our Rotax parts catalog, then check the reference and engine of each product. If you do not know the reference, send us a photo, the year and engine information via Identify your part.
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