Rotax MAX Plasma Cylinder Senior 
Art. 413578

Rotax 125 MAX Senior Plasma Cylinder: Key Features

• Part number: 413578
• Engine class: Rotax 125 MAX Senior
• Cylinder technology: Plasma coating
• External marking: ROTAX
• Manufacturing quality: Precisely defined bore tolerances and enhanced quality control
• Compatibility: Interchangeable with the previous Senior cylinder; the required additional parts must be taken into account
• Additional parts: Three components for the exhaust valve area, to be ordered separately

What Makes the New Rotax Plasma Cylinder Stand Out?

The Rotax Plasma cylinder is the further-developed cylinder generation for the Rotax MAX Senior. Similar to the introduction of the EVO generation at the time, it represents another step forward in the manufacturing of ROTAX MAX engines.

The plasma coating and revised manufacturing processes represent modern cylinder technology. A key focus is on precisely defined bore tolerances and improved manufacturing quality control. The aim is to ensure consistent and reproducible engine quality.

The improved manufacturing tolerances support precise piston-to-cylinder matching during engine assembly. This provides a good basis for repeatable assembly and consistent performance characteristics. However, the Plasma cylinder should not be regarded as a guaranteed performance upgrade. Compliance with the manufacturer's specifications and the correct combination of engine components remain essential.

Comparison: Plasma Cylinder vs. Previous EVO Cylinder

The new Plasma cylinder differs from the previous EVO cylinder primarily in its coating, external marking and available tolerance groups. For correct engine assembly, the defined bore dimensions and accurate piston-to-cylinder matching are particularly important.

Tolerance Groups A and AB: What Do the Markings Mean?

The A and AB markings are not quality grades. They identify cylinder bore tolerance groups and help ensure the correct matching of piston and cylinder during engine assembly.

The correct piston-to-cylinder match must be determined according to the applicable manufacturer's specifications and prescribed measurements. The tolerance group alone does not replace a proper check of piston-to-cylinder clearance.

Our service at KartStore: If you order a suitable ROTAX piston together with the cylinder from us, we can measure the cylinder bore and match a suitable piston according to the applicable manufacturer's specifications. Simply mention in the order comments that you would like to use this service. Bore measurement and piston matching are free of charge when the cylinder and piston are ordered together; the piston itself is charged separately.

Compatibility and Required Additional Parts

The Rotax Plasma cylinder for the Senior MAX is interchangeable with the previous Senior cylinder. However, converting to the new version requires three additional components in the exhaust valve area. These parts are not included with the cylinder and must be ordered separately.

Additional Piston Components

Please note: In addition to the three components listed above, the correct piston and, depending on the condition of the engine and the scope of the work, other piston components such as the piston pin, piston pin bearing and piston pin circlips should also be checked during an engine overhaul. These parts are not automatically included with the cylinder.

If you are unsure which parts you need, we will be happy to help you put together your order.

ROTAX Service at KartStore

At KartStore, you receive not only genuine ROTAX spare parts but also technical support from an official ROTAX service partner. As a ROTAX Service Centre and sealing partner, we provide support for maintenance, repairs and authorised warranty work in accordance with the applicable requirements.

• Technical advice: Assistance with selecting the right spare parts and answering compatibility questions.
• Maintenance and repairs: Professional work on ROTAX engines according to the individual job requirements.
• Authorised warranty work: Carrying out the relevant work in accordance with the applicable ROTAX warranty conditions.
• Sealing: Service as a ROTAX sealing partner in accordance with the applicable regulations.
• Assembly and technical inspection: Assistance with correct assembly and inspection of relevant components and dimensions.

Correct component selection is particularly important for cylinder and piston components. If you would like not only to purchase the Plasma cylinder but also have it professionally installed or your engine inspected, please contact our service team.

Rotax Plasma Cylinder and the 2027 RMC Regulations

For the planned use in Rotax MAX Challenge events from 1 January 2027, the following requirements are anticipated:

• Senior MAX: Plasma cylinder optional
• Junior MAX: Plasma cylinder optional
• Mini MAX: Plasma cylinder mandatory
• Micro MAX: Plasma cylinder mandatory

Status: 22 October 2026. Subject to change. Before use, please check the currently applicable technical regulations and the rules of the relevant racing series or event.

Who Is the Senior Plasma Cylinder Suitable For?

The Rotax 125 MAX Senior Plasma cylinder, part number 413578, is suitable for drivers and teams who need a replacement cylinder for their Senior MAX engine or wish to upgrade to the new cylinder generation.

For competition use in particular, compliance with the technical requirements, correct piston-to-cylinder matching and professional assembly are essential. Anyone looking to bring their engine up to the current technical standard should consider not only the cylinder but also the required additional parts and the condition of the other engine components.

Technical Specifications

Frequently Asked Questions About the Rotax Senior Plasma Cylinder

Can I use the Plasma cylinder in my existing Senior MAX engine?

According to the product information available, the Plasma cylinder is interchangeable with the previous Senior cylinder from model year 2004 onwards. Three additional components in the exhaust valve area are required for the conversion. Before ordering, check the exact engine version and the applicable manufacturer's specifications.

Are the additional parts included?

No. The three required additional parts, ROT450415, ROT251337 and ROT250230, must be ordered separately. The correct piston and, where required, the piston pin, piston pin bearing and piston pin circlips are also not automatically included with the cylinder.

What do the A and AB markings mean?

The letters identify cylinder bore tolerance groups and are not quality grades. They help with matching the piston and cylinder during engine assembly. The prescribed measurements and applicable manufacturer's specifications are decisive.

Will the Plasma cylinder be mandatory for Senior MAX from 2027?

According to the currently anticipated requirements, the Plasma cylinder will be optional for Senior MAX from 2027. As technical regulations may change, always check the current regulations for the relevant series before racing. Regardless of whether it is mandatory, the conversion may be of interest to drivers who want to equip their engine with the current cylinder generation.

Can the Plasma cylinder be repaired or honed?

Due to the special coating, work on the cylinder bore must be carried out using a suitable process and in accordance with the applicable ROTAX specifications. Whether repair is possible and permitted in a specific case must be assessed by a specialist. Please contact us as an authorised ROTAX Service Centre.

What are the benefits of measuring the cylinder when selecting a piston?

Measuring the cylinder bore and taking the manufacturer's specifications into account helps identify a suitable piston. When you order the cylinder and piston together from KartStore, you can use our free measurement and matching service. Simply add a note to your order.

How can I identify the new Plasma cylinder?

The new Plasma cylinder carries the ROTAX marking on the outside. The previous cylinder generation is marked ROTAX RACING. The part number and manufacturer's documentation should also be used for unambiguous identification.

Notes on Assembly, Maintenance and Sealing

Assembly and inspection should be carried out by an authorised ROTAX Service Centre such as ours, in accordance with the latest manufacturer's specifications. Particular attention must be paid to correct piston-to-cylinder matching, compliance with measurement requirements, use of the required additional exhaust valve components and proper sealing.

Opening or modifying a sealed engine independently may affect goodwill claims and eligibility for competition. The specific consequences depend on the applicable ROTAX conditions and the regulations of the relevant racing series. For this reason, discuss any work on the engine with an authorised service partner in advance.

* Goodwill benefits are provided exclusively in accordance with the applicable official ROTAX warranty and goodwill conditions.