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Regular price £453.99 GBP
Regular price Sale price £453.99 GBP
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Ariel Square Four 4G MkII 1953-1959 Piston Kits & Cylinder Liners

Also fits MKI version engine

Pistons (4) Ring Sets (4) Piston Pins (4) Circlips (8)

Size: Std = 65mm

Replacement Piston kit designed by IMD Piston Co. and manufactured for IMD Piston Co. England

IMD Ref. P11024-00


Cylinder sleeves / liners x 4 , Westwood UK.

For Aluminium Barrels Only

NOTE: The sleeves are un-finished condition, will need specialist machining/reboring service before use

Material Specification: Centrifugally spun grey cast iron, Hardness 200-270HB. 93-104 HRB
Euro Spec. DIN 1691 GG30 . US Spec ASTM-A48 / Class 30


The pistons are within a 5 gram range of the original piston,

The correct offset on the thrust side of the piston has been engineered into our pistons; not all manufacturers follow this design as laid down in the original specifications.

The ring sets utilise the 3 piece oil control type offering excellent sealing to the cylinder wall.

The piston pins are internally tapered, and are constructed using SCM415 material achieving virtually the same weight as the original pin..


We offer a worldwide postal service. See rates


Bruce Longman, who advises that pistons with NO offset were originally specified by Ariel for the MKI engine, but offset pistons are a good idea to fit as they make the engine run quieter. He also informs me that the MKII pistons that you have had made, will fit as they are, in a MKI cast iron engine. I could machine them down flat if I wished but don't have to. (D Colville with Bruce Longman, Ariel Owners Club in a recent Email Dec 2013.

As approved by The Ariel Owners Club England, Dec 2013

About Us

Established in 1989, IMD Pistons is one of the largest piston suppliers in the UK. Based in Cheshire, we distribute parts for a wide variety of motorcycle manufacturers worldwide. We have over 6,000 reviews on our eBay store, and work with a host of affiliates. If you would like more information, please don't hesitate to contact us.


Please contact us for more information

Shipping (UK, Ireland & Channel Isles)

Items will be dispatched on the same day, if the order is placed before 3PM GMT, and if the order is placed after 3PM, please allow 1 working day. Items are sent mainly via Royal Mail Tracked, and for higher value items, we use DPD (Next Day). If you wish for your items to be sent via courier, please contact us and we can arrange this.

Shipping (International)

Items will be dispatched within 1 working day of order confirmation. We aim to process all international orders before 1pm, and if you place an order after 1pm GMT, then your items may be processed the next day due to our courier collection time. Our items are mainly sent via DPD Local, however this is not possible for all orders and locations. We understand that some postal services in certain areas face significant delays, so for any shipping questions, or to obtain a quote for a courier delivery, please contact us.


We will offer a full refund, partial refund, or an exchange for any items wanting to be returned within 30 days from purchase date, and we do our best to ensure that you receive the correct parts before refunding you, as we appreciate the items that we sell, can be somewhat hard to locate from other sources. If you wish to return your goods, please kindly meet the conditions that we provide below.
Ensure that the items are not damaged, or used. If the items arrive to our premises and there are signs of use / damage, then you may be liable to a charge. We understand however that some of our items are somewhat hard to check when installing, so we do allow certain damage / scratches etc.
Ensure that the original invoice which we provide, is inside the parcel when returning, and if this is not possible, please write / type on paper, your name, your order number or invoice number (IMD-XXXX), and reason for return. We may call you upon receipt of the returned goods, if no communication has been made prior to the return.


All IMD pistons are made from the latest specification silicon aluminium alloy material.

This conforms to the required percentages of specialist metals, the most important of which is silicon. Silicon has been proved conclusively over a prolonged period, to give the best ring groove wear rates coupled with a low coefficient of low expansion rates. Strength has been achieved using a modern construction technique which has allowed the weight to be reduced in the piston. The weight of the piston is the most important factor in engine design, since the effect of reciprocating weight is transferred directly in terms bearing loads, engine balance and maximum permissible speed. The lighter the pistons are, then the lower are the loads on the crankshaft main bearings.

IMD have achieved piston weights comparable with the original parts, and will in the future improve upon this through innovative design.

This reduction of weight is now common place in automotive piston manufacturing worldwide, our pistons conform to this industry practice without any compromise, and are kept to the lowest level concomitant with adequate strength.


Please note: All motorcycle & automotive components supplied from this site/listing must be fitted by a qualified Engineer using the correct appropriate equipment and using the necessary technical information. No liability can be accepted for components incorrectly fitted, and any such failure after installation

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