P&M & Triple Cycles Strong Cylinders

There is a bit of history about replacement cylinders. It could be said that the first were the Hyde cylinders, although I believe these were first drawn up and made for and by the Quaife Engineering company. It was for the sidecar outfit that they were sponsoring. It was constantly breaking standard muff cylinders. As an aside, it is this outfit that the Belgian couple, the Ledermans, now own and ride.

There were / are four (maybe five) alternate cylinder available. I must one day find the time to write a proper webpage....... In production order:

The Hyde cylinder seems to be in mainly two forms, both with the poorly styled but easier to cast, course fining, at '850' and '1000' Both there variations are generally supplied with lightly modified T120 Bonneville pistons.

Alistair Laurie did have a billet barrel at a Road & Racing Show long ago, but I don't know if any were produced or any other details.

The 'Pretech' was next to see the light of day. Machined from a solid piece of alloy. Supplied with iron liners (I believe) or with a plated bore. No (alloy) liners in the plated bore one, plated directly to the parent block. I know a couple of sizes were made, and one solo rider (Terry Moring) used a set and two sidecar crews used them too. I know one of the sidecar crews did OK with it, but the other lost plating on at least one cylinder on two occasions. After the second loss of plating I was asked to fit iron liners to this block and it then ran fine. Problem Solved.

The P&M / Triple Cycles cylinders were next along. Although Richard and I had discussed them over a few years, and made one (later aborted) production order with a machinist for billet items, it took a while to produce the casting pattern and make the first production. We had decided to keep tightly to the rules of the Classic Racing Motorcycle Club that stated that engine exterior appearance must not change, so ours are cast with standard fining and features. However clever design changes (they could be called 20/20 cylinders, no changes visible from 20 feet or 20 miles per hour) result in a MUCH stronger cylinder. A high spec alloy is used to make them and clever pressure treatments and heat treatments are used in manufacture. We produce them in many forms at '750', '850', '930' (using a 77mm stroke and shorter connecting rods so that the engine exterior appearance does not change) and '990' (using the same short rod and an 82mm stroke) versions.

I believe the business that trades as 'Nova Triples' are producing a block too. I saw Neil Beadling and an associate at a piston manufacturers stand at an automotive trade show, and I have seen some finished items. Sorry, no picture available of these, and I know at least one is running on the 'Omega' made piston the P&M and I now use.

Rob van der Vegt in The Netherlands has been making noises about his developments too. These have been aired and detailed in Triple Echo. Plated bore once again. I have seen a picture of the prototype casting and believe this is to be machined soon.

Any large block that has been made using either new or used standard muffs is very suspect. The old Hadleigh Custom business used to import to the UK kits for doing this from the USA (Precision Machining or perhaps Routt) and other UK manufacturers have taken this route too. As the blocks are very very weak they often break the cylinder casting just above the base flange and often suffer terrible head gasket problem

As I have no detail knowledge of other manufacturers items I believe only the P&M / Triple Cycles cylinders are currently supplied with correctly made forged custom pistons. I have no knowledge of the manufacturing source for any other block. Any alternates that use a version of the T120 piston are very 1970's in approach.

Having been down the development road and learnt a few expensive lessons I'd suggest that anybody that was thinking of purchasing an alternate cylinder look very carefully at the record of the supplier and how willing they are to stand behind their product. I saw the mess made within one engine when one of the early plated bore cylinders dropped its plating. Messy, and very very expensive for the owner.

Let's be careful out there........

The P&M / Triple Cycles Block

P&M / Triple Cycles Strong Cylinder

The Cylinder above shows two head dowels in position and the extra 8 holding down screw threads that we use on high power (any capacity) variations. These are optional.

Pistons available

Variant 70mm Stroke 77mm Stroke 82mm Stroke
Nominal 850cc 930cc 990cc
Block Height 3.350" 3.375" 3.500"
Piston A 11 : 1 12 : 1 11.8 : 1
Piston B 10 : 1 10.9 : 1 10.8 : 1
Piston C 9.5 : 1 10.4 : 1 10.3 : 1
Piston D 8.3 : 1 9.0 : 1 9.0 : 1 *

* denotes a special that has a changed gudgeon pin / crown relationship. All the others are identical in this respect and higher compression ratio versions can be lowered to a lower compression ratio specification by reshaping the crown.

The BOLD text within the nominal compression ratio cell in the above table shows that a pistons box is marked in this way.

Price of these Components

At this time (July 2004) the UK purchase price of these components, is:
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Triple Cycles
95 Wanstead Park Road
Telephone: +44 20 8215 4583 (answerphone only, unless by arrangement)
Facsimile: +44 20 3137 2295

Copyright © 2004 Philip Pick
Version 0.1 Date July 2004