November 2021: A new batch of these popular pistons have now come in and are available again (and updated price is actually fractionally lower than was anticipating).

This is a 79.62mm (500cc) forged slipper piston to fit Norton Racing International and Longstroke Manx (i.e. 79mm and 79.62mm x 100mm Longstroke singles) fitted with the 1.00" wide (M30/Manx type) Gudgeon Pin/Little End. Manufactured by top performance piston manufacturer - Omega Pistons.  Note - this is is the same piston as Item 0396/0397 - other than this type is designed to accept the M30/Manx style conrod, where the Gudgeon Pin width was only 1.00" wide, rather than the 1.200" inch wide roadgoing International type conrod/Little End.

They are high quality forged 'slipper' type pistons from top quality manufacturer Omega Pistons, made specially for us - to the same vital dimensions of the pre-war International/M30 type Hepolite Ref 5288 piston form - one of these being supplied to Omega as a pattern (see picture for original piston alongside ours). This piston form was the standard higher compression piston suitable for petrol (rather than a 'dope' piston), as fitted to Norton International and M30 engines. Although I cannot be precise - the last time I fitted one of these original Hepolite pistons to an International engine it gave a compression ratio of approximately 9.5:1.

As you can see from the photos, the profile of the crown, and its position in relation to the gudgeon pin centre line is identical to the original - and as far as I am aware, this is the first time this pre-war type piston has been available for many years, so you can be confident it should be as per originally fitted. 

Fitting Information - Please Read:

Little End Width: This listing is for a piston to fit a Norton M30 (Racing International) or SOHC Manx engine - i.e. the piston is designed to take the racing type conrod which has a Little End width of 1.000"

if you are not sure - check the width of your conrod - original International engines (i.e. aluminium crankcase models) normally had a connecting rod with a width of 1.200" width, while Racing International/Manx (i.e. magnesium crankcase) conrods had a slimmer Little End width of 1.000",

Therefore, this item is for the slimmer racing conrod M30/Manx SOHC engine, if you require the wider International width, see the seperate Item listing for the International type pistons - (i.e. Item number 0396 or 397.  We can also supply a higher compression ratio version of this piston, for use with alchohol or methanol - Item 0686.

Bore size: This piston is to fit a bore size of 79.62mm - which was the standard (STD) bore size for a SOHC Manx Norton (i.e 499cc rather than 490cc of the roadgoing International).  Norton's did this because for the racing models, they did not want to waste any available cc.  We can also offer the Internatonal type piston (Item 0397) in a further oversize of 80.13mm - but not in the slimmer 'Manx type' Gudgeon pin option - so if requiring a piston in that oversize it may be possible to use the Inter type piston (i.e. 80.13mm), which is Item 0397, but you would need to satisfy yourself you are comfortable to fit spacer washers either side. 

As a Norton International Model 30 (500cc) STD piston was originall 79.00mm - this 79.62mm is broadly equivelant to an originall 79mm STD + 0.025" piston on an International model (please check your original piston and bore), and the barrel should be bored to that 79.62mm dimension.  Email us if you require more information on this

Gudgeon Pin To Base of Barrel Height: It is important before ordering pistons for post-war SOHC (and early Longstroke DOHC) engines, to check the distance between the centre of the Gudgeon Pin and the base of the piston crown - as some later engines had a shallower barrel/cylinder head spigot - and to allow for this the piston was slightly different.  These pistons have a distance of 34.0mm between the Gudgeon Pin centre and base (i.e. circumference height) of the piston crown. Email us if you require more details.

Piston Weight: Weight of these pistons with rings/circlips etc is @465g (which is compatable with original pistons).  If you require information for 'balancing' your crank to this piston (or are just not sure if your crank is correctly balanced), then email us for details on how to do this.   

Compression Ratio:  The compression ratio we quote here is a guide only, as over the years the SOHC engine was manufactured there were many variations in barrel, head height, valve diameter etc, all of which can affect the compression ratio. However, the Hepolite Ref 5288 piston used as the pattern for our pistons is a good indicative dome for the most normal piston crown fitted to International Model 30 engines running on good quality pump petrol - similar to offered today (i.e. not post War 'Pool' petrol, which sometimes necessitated lowering compression ratio).

It was normal practice when fitting SOHC pistons to measure the swept volume (i.e. stroke and exact bore size) and the combustion chamber volume when the piston is at TDC - and then add or remove compression plates to get to a desired volume.  To help with this we can supply nice quality lasercut compression plates in two thicknesses (Items 0275 and 0275b) - but it should be remembered when changing the barrel/head height on SOHC (and DOHC) Norton engines, you also need to check the vertical coupling clearance is still within limits.  Email us if more information on this is required, and we also offer a useful MS Excel utility on our www.RacingVincent.co.uk Download page for calculating compression ratios for a given CC to swept volume.

This is a 79.62mm bore (500cc) forged slipper piston to fit Norton Racing International (i.e. M30) and Longstroke Manx 79.62mm x 100mm Longstroke singles - this version is a very high compression type meant for alchohol/methanol or racing fuels (not for petrol) and for competition use only. 

They are high quality forged 'slipper' type pistons, made by top performance piston manufacturer - Omega Pistons.

This listing is for the very high compression version of our piston - designed to run on methanol or alchohol with a very high dome, which will provide a much higher compression ratio than are other 'petrol' type pistons.  It is of the M30/SOHC Longstroke Manx type - i.e. the piston is designed to take the Manx type conrod which has a Little End width of 1.000" (if you are not sure - check the width of your conrod - original Racing International/Manx conrods had a Little End width of 1.000", while International was 1.200". We only supply this 'methanol' version piston to fit the 1.000" width conrod, but you can mill the inner gudgeon pin faces yourself if you wish to fit it to the Inter type conrod - not a difficult job for anyone with a vertical milling machine.

As you can see from the photos, the profile of the crown, and its position in relation to the gudgeon pin centre line is much greater than that of the normal Hepolite high compression International petrol version, and is designed to give ultra high compression for use when using alchohol fuels like methanol - for racing purposes only.  For comparison - see the photograph that shows this piston alongside our Omega 'petrol' piston.  Do not purchase this piston if you are intending to run your engine on the road, using pump petrol fuel - for that see instead the listings 396/397/398.

However, this piston could also be used for other high octane racing fuels - providing you know the optimum compression ratio with other fuels, and have measured the compression ratio, once fitted.  It is always possible to add compression spacer rings (which we offer) - but remember with SOHC engines - this may also entail amending the top Oldham Coupling height (we can also offer varying thickness couplings)

We have copied the crown of this piston from another period methanol competition piston, designed to fit into the Norton SOHC Longstroke Manx type cylinder head hemisperical cylinder, with valve cutaways to accomodate most SOHC racing valve sizes (and is sided - with the inlet valve cutaway slightly larger than the exhaust valve cutaway - ensure you check this when you fit the piston)

It is difficult to be specific about the compression ratio - as it will be dependent on the specification of the engine you are fitting it to - crankcase height, barrel length, spigot length will all play a part, but I would estimate ratio to be somewhere between 11:1 - 14:1 dependent on your engine spec and barrel spacers fitted. 

Note: As with any racing engine - it is very important that if you are intending to use this piston you must satisfy yourself that when fitted, satisfactory clearance to the valves at full lift and cylinder head are achieved.  We recommend a minimum of 0.060" (60 thou) clearance should be achievable at any point on the piston crown or valve cutaways (at full cam lift).  Use plasticine or similar to check on assembly before running the engine.  If the necesaary clearance is not available on first fitting then add suitable barrel spacers until it is achieved.  Remember as well, that by altering the barrel height to alter compression ratio you may also need to amend the vertical shaft assembly length - to help achieve this we also sell barrel spacers (item 0275) and different length Oldham Couplings (Item 0684).

And finally, if running on methanol/alchohol fuels - you will also need to ensure your carburettor jetting is setup correctly as well.  As an indication (indication only! - it varies by engine), it is not unusual for a 500cc Inter/M30 engine running with an Amal TT/RN carb on methanol to need a main jet between 900 - 1400, compared to @450 main jet on petrol.  Likewise an Amal pilot jet of 120 will be required.

We hope that for anyone already racing classic motorccycles everything we have said here will be second nature and that when running alchohol fuels it is fully understood that clearances are a major concern and needs careful checking - but if you have any doubts about this process we advise you not to purchase this piston.  With that in mind we re-iterate our standard disclaimer that although we ensure our parts are manufactured to the highest possible standards - due to the nature of usage, we can not take any responsibility for issues caused from usage of this piston - responsibility of setup is entirely with the purchaser.  Hope this goes without saying, but we are saying it anyway!  We use these pistons in our racing engines but - go through exactly the same checking process on every engine build - if need be we will alter engine configuration or even amend valve cutouts to suit the engine specification on build, so bear in mind you may need to do so as well!

Weight of piston with rings/circlips etc is @495g

Bore size: This piston is to fit a bore size of 79.6mm - which was the standard (STD) bore size for a SOHC Manx Norton (i.e 499cc rather than 490cc of the roadgoing International . . . the racing bikes did not want to waste available cc!). If you are fitting this piston to a Norton International : then 79.62mm equates to International 79mm STD + 0.025".  When boring your barrel it needs to be finished to : 79.62mm 

This is a 79.62mm (500cc) forged slipper piston which copies the same vital dimensions as the original 1940's-50's Norton Heplex 572 OHV (Model 18 and ES2) piston, other than having a slightly raised crown - which on most OHV models should relate to an estimated circa 8:1  compression ratio.  As with our SOHC slipper pistons - these are the highest quality forged slipper pistons made by top manufactuer Omega.  

Price is per piston - piston includes rings, Gudgeon Pin and circlips

Background Information:

As can be seen in the accompanyning photographs - original post war (Heplex) OHV Model 18 and ES2 pistons were most often of the full skirt and flat dome variety - as per the original Norton OHV piston in the photo (taken from a late 1940's standard ES2 many years ago).

The most importand dimensions which we have copied into these Omega pistons are the correct Gudgeon Pin Diameter, the width of the OHV/SV con rod Little End distance and most importantly - height from the centre of the gudgeon pin to the base of the piston crown, and with this, the same base piston crown chamfer as the original Heplex Model 18/ES2 piston. 

However, we have had these pistons made with a slightly raised crown in the centre -  raised by 10mm at the centre, which should provide a compression ratio of approximately 8:1 (as original pistons and motor specifications in the 1940's were more suited for the lower quality petrol available at the time).  As can be seen - the valve cutaways have also been enlarged slightly to allow for this.

Norton Side Valve 16H piston usage: It should be noted that the WD side valve 16H Norton, and the later Postward 16H models, all used a piston similar to the ES2, but this piston also had a raised crown, to achieve a similar compression ratio to the OHV model in the larger SV combustion space (but of course, original 16H pistons did not have the need for valve cutaways and were normally of a more heavyweight skirt construction for long life.  The construction of these Omega pistons may make them lighter than original 16H pre-war pistons (although post-war type were lighter and comparable) - but are a viable alternative to be considered for 500cc 16H sidevalve models.  A picture of an original WD sidevalve piston is shown in the accmpnanying photos for comparison

Norton CS1 (SOHC) Usage:  These pistons are similar to the higher compression 'International' pistons we also offer (Item 0396 and 0397), but with slightly different dome dimensions (and of course, a lower compression ratio than the International type).  If you have either a Walter Moore or Arthur Carroll type CS1, and are looking for a lower compression version of our International piston, then email us on sales@racingvincent.co.uk to confirm if these will fit your engine 

Norton Late SOHC Inter/Manx 500cc (Early 50's) Usage:  It should be noted that our main SOHC pistons (Item 0396-0398) are intended for the 'deep barrel spigot' type Inter/SOHC Manx engine, which was used on most SOHC engines until sometime in the late '40's/early 50's.  At some point around this time a shallower barrel spigot and combustion chamber seems to have been adopted.  We do not offer a piston specifically for that later 'shallow barrel spigot' type 500cc SOHC engine, but if you have an engine of that later type - this piston may turn out to be more suitable to adopt.  It is important to measure the height between the centre point of the gudgeon pin and the top lip of the barrel to confirm the type of piston required - if unsure - please email us and we can confirm the important dimensions of this piston. It is important to check this beforehand - as unfortunately we cannot accept returns once a piston has been removed from its packaging and trial fitted.

As a final point - although most people associate 'Slipper' type pistons with racing engines - but for all uses, they are a high quality forged piston that have a steady and reliable expansion rate and are very stiff and rigid in construction.  And surprisingly - the total 'touching' side wall of the thrust face of these Omega pistons is actually fractionally more than the original Heplex 572 Norton piston shown in the photograph.

Fitting Pistons: As with the fitting of all pistons to older engines (which may have been previously modified) - we strongly advise you satisfy yourself there is sufficient piston to head/clearance in your own engine when fitting one of these pistons - I always put a thin layer of plasticine on the top of a piston crown - then slowy turn the assembled engine over by hand first - there should be at least 60 thou of clearance on valve cutaways and to ensure the piston is not touching the head at any point.  a Digital caliper, using the depth gauge prong into the plasticine is ideal for this.  

Piston Weight: These pistons weigh 450grams complete with Gudgeon Pi, rings and circlips - which is within a couple of grams of the weight of the original Norton Heplex 572 piston (unlike other non forged modern OHV substitutes, which are considerably heavier).  Therefore the balance charateristics when using these pistons should be comparable to original specification 

Little End Width: This listing is for a piston to fit a Norton OHV/SV or CS1 specification engine - i.e. the piston is designed to take the Norton conrod which has a Little End width of 1.200"

Bore Size Information: 

Original OHV and SV Norton (Longstroke) 500cc pistons had a standard bore of 79mm, and were then offered in standard oversizes of +20, +40 and +60 thousandths of an inch.  Occasionally +30 thou oversize can also be found.

We can currently only offer these pistons in two bore sizes - 79.62mm (which is this Item listing) or 80.13mm (Item 1062)

79.62mm in OHV/SV oversize parlance can be converted to 79mm + 24thou, while the 80.13mm version can be converted to 79mm + 44thou.  Hopefully one of these two 79mm oversizes will be suitable for your engine (or of course you can consider re-lining your cylinder if already out at +60.  If based in the UK we can recommend people we have used for this in the past).

When taking your barrel to be bored/honed, ask for the barrel to be honed to the exact size shown on here (79.62mm or 80.13mm), Omega will have worked out the correct clearances for these pistons for that bore.

In case you are wondering why we have chosen these two bore sizes for our pistons - our original Omega forge patterns were made for the Manx Norton piston size of 79.62mm and one oversize of this - as original Manx Longstroke pistons were a slightly larger bore, to allow the full 499cc capacity to be used for Grand Prix racing.  These two sizes also allowed a useful 'oversize' piston for standard 79mm engines.

This is a 79.62mm (i.e. 79.62mm +20thou oversize) 500cc forged slipper piston which copies the same vital dimensions as the original 1940's-50's Norton Heplex 572 OHV (Model 18 and ES2) piston, other than having a slightly raised crown - which on most OHV models should relate to an estimated circa 8:1  compression ratio.  As with our SOHC slipper pistons - these are the highest quality forged slipper pistons made by top manufactuer Omega.  

Price is per piston - piston includes rings, Gudgeon Pin and circlips

Background Information:

As can be seen in the accompanyning photographs - original post war (Heplex) OHV Model 18 and ES2 pistons were most often of the full skirt and flat dome variety - as per the original Norton OHV piston in the photo (taken from a late 1940's standard ES2 many years ago).

The most importand dimensions which we have copied into these Omega pistons are the correct Gudgeon Pin Diameter, the width of the OHV/SV con rod Little End distance and most importantly - height from the centre of the gudgeon pin to the base of the piston crown, and with this, the same base piston crown chamfer as the original Heplex Model 18/ES2 piston. 

However, we have had these pistons made with a slightly raised crown in the centre -  raised by 10mm at the centre, which should provide a compression ratio of approximately 8:1 (as original pistons and motor specifications in the 1940's were more suited for the lower quality petrol available at the time).  As can be seen - the valve cutaways have also been enlarged slightly to allow for this.

Norton Side Valve 16H piston usage: It should be noted that the WD side valve 16H Norton, and the later Postward 16H models, all used a piston similar to the ES2, but this piston also had a raised crown, to achieve a similar compression ratio to the OHV model in the larger SV combustion space (but of course, original 16H pistons did not have the need for valve cutaways and were normally of a more heavyweight skirt construction for long life.  The construction of these Omega pistons may make them lighter than original 16H pre-war pistons (although post-war type were lighter and comparable) - but are a viable alternative to be considered for 500cc 16H sidevalve models.  A picture of an original WD sidevalve piston is shown in the accmpnanying photos for comparison

Norton CS1 (SOHC) Usage:  These pistons are similar to the higher compression 'International' pistons we also offer (Item 0396 and 0397), but with slightly different dome dimensions (and of course, a lower compression ratio than the International type).  If you have either a Walter Moore or Arthur Carroll type CS1, and are looking for a lower compression version of our International piston, then email us on sales@racingvincent.co.uk to confirm if these will fit your engine 

Norton Late SOHC Inter/Manx 500cc (Early 50's) Usage:  It should be noted that our main SOHC pistons (Item 0396-0398) are intended for the 'deep barrel spigot' type Inter/SOHC Manx engine, which was used on most SOHC engines until sometime in the late '40's/early 50's.  At some point around this time a shallower barrel spigot and combustion chamber seems to have been adopted.  We do not offer a piston specifically for that later 'shallow barrel spigot' type 500cc SOHC engine, but if you have an engine of that later type - this piston may turn out to be more suitable to adopt.  It is important to measure the height between the centre point of the gudgeon pin and the top lip of the barrel to confirm the type of piston required - if unsure - please email us and we can confirm the important dimensions of this piston. It is important to check this beforehand - as unfortunately we cannot accept returns once a piston has been removed from its packaging and trial fitted.

As a final point - although most people associate 'Slipper' type pistons with racing engines - they are a high quality forged piston that have a steady and reliable expansion rate and are very stiff and rigid in construction.  And surprisingly - the total 'touching' side wall of the thrust face of these Omega pistons is actually fractionally more than the original Heplex 572 Norton piston shown in the photograph.

Fitting Pistons: As with the fitting of all pistons to older engines (which may have been previously modified) - we strongly advise you satisfy yourself there is sufficient piston to head/clearance in your own engine when fitting one of these pistons - I always put a thin layer of plasticine on the top of a piston crown - then slowy turn the assembled engine over by hand first - there should be at least 60 thou of clearance on valve cutaways and to ensure the piston is not touching the head at any point.  a Digital caliper, using the depth gauge prong into the plasticine is ideal for this.  

Piston Weight: These pistons weigh 450grams complete with Gudgeon Pi, rings and circlips - which is within a couple of grams of the weight of the original Norton Heplex 572 piston (unlike other non forged modern OHV substitutes, which are considerably heavier).  Therefore the balance charateristics when using these pistons should be comparable to original specification 

Little End Width: This listing is for a piston to fit a Norton OHV/SV or CS1 specification engine - i.e. the piston is designed to take the Norton conrod which has a Little End width of 1.200"

Bore Size Information: 

Original OHV and SV Norton (Longstroke) 500cc pistons had a standard bore of 79mm, and were then offered in standard oversizes of +20, +40 and +60 thousandths of an inch.  Occasionally +30 thou oversize can also be found.

We can currently only offer these pistons in two bore sizes - 79.62mm (Item 1061) or 80.13mm (this item listing)

79.62mm in OHV/SV oversize parlance can be converted to 79mm + 24thou, while the 80.13mm version can be converted to 79mm + 44thou.  Hopefully one of these two 79mm oversizes will be suitable for your engine (or of course you can consider re-lining your cylinder if already out at +60.  If based in the UK we can recommend people we have used for this in the past).

When taking your barrel to be bored/honed, ask for the barrel to be honed to the exact size shown on here (79.62mm or 80.13mm), Omega will have worked out the correct clearances for these pistons for that bore.

In case you are wondering why we have chosen these two bore sizes for our pistons - our original Omega forge patterns were made for the Manx Norton piston size of 79.62mm and one oversize of this - as original Manx Longstroke pistons were a slightly larger bore, to allow the full 499cc capacity to be used for Grand Prix racing.  These two sizes also allowed a useful 'oversize' piston for standard 79mm engines.

This is a listing for the Little End Bush to fit Norton Single Cylinder models - with 4 variation types.  They are available to fit most SOHC models (road going and competition type), OHV and SV models.  We also manufacture a type to allow the fitment of BSA type pistons, with 0.750" Gudgeon Pin diameter. 

We manufacture these Little End bushes in a high quality Leaded Bronze - PB2 (which has a higher Tin content than others to give very hard wearing properties), and is widely regarded as the best material for Little End manufacture (and of course more expensive than many other bronze types).

We manufacture these Little End bushes to the 'Standard' Norton outer diameter tolerance that would have been used when they were first manufactured - therefore when fitting these bushes to your Con Rod, it is important to confirm the condition of your con rod Little End Eye, and to confirm the condition and diameter of the old Little End bearing your are removing - to ensure it has not gone oval from excessive use or age . . . and to confirm that the the Outer Diameter of our Little End Bush (which are CNC machined to a very close tolerance of the original Norton 'STD' tolerance interference fit), are at least the same diameter as the bush being removed - in case your own Con Rod has already had an oversize Little End fitted in the past. 

Sorry, but we cannot accept Returns on these items once any attempt to fit them has been made (as they will always mark in the process of fitting) - so please ensure you have confirmed dimensions before attempting to fit.

All four types of Little End bushes have a shallow 'coarse scroll' innner oil way running across their width - as per original Norton Little Ends, to aid oiling.

All 4 types of Little Ends have been manufactured to very accurate tolerances - and examples have been 'Test fitted' into original Norton conrods.  The internal bore tolerance of the bushes has been set so that once pressed into a 'Standard' Norton fit con-rod, and any burr's from pressing removed. that a standard Norton Gudgeon Pin will just slide into the bush.  However - as with all Norton parts - con rod tolerances can vary - so you must check the bush after fitting, to ensure the gudgeon pin will turn smoothly in the bore of the new bush.  (As with fitting any plain Little End bush) - if there is any tightness of the Gudgeon pin, it may require gentle hand scraping or light reaming (with lots of light cutting oil), to ensure the pin will spin freely 

Four Types of Little End are currently available, with the following details:

1077_1: Standard SOHC (International), OHV or SV Type - Already pre-drilled with Standard Norton 'Diamond' Type Oil Holes:

This is the 'standard' roadgoing type Little end, to accept Norton 0.875" Gudgeon Pin piston, with 1.150" width con rod Little End eye width (this can vary by @+/- 10 thou by conrod - as this type of Little End was used on most roadgoing Norton single cylinder models over a 30 year period - from early 1930s to late 1950's).  These little ends have the 'regular' Norton 'Diamond' pattern 4 oiling holes pre-drilled, for those customers who would prefer not to drill the holes themselves after pressing the new Little End into the conrod.  However, this means a little more care must be taken when fitting the new Little End bush, to ensure the oil holes in the bush are in-line with those in the conrod - this can be easily achieved by using a permanent felt pen to draw lines over the top of the conrod.  The holes in our bush have been copied exactly from an original Norton bush - and pressed into an original Norton con rod - to ensure they line up.  However, as per the width, there were fractional variations on con rods over the years - so the holes can vary fractionally.  It is not critical if a hole does not line up exactly - providing each of the 4 holes are close and still allow oil to flow through

- Gudgeon Pin Diameter:  0.875"

- Width: 1.150"

- Oil Holes: 4 Hole Diamond Pattern Pre-Drilled

Weight of Little End: 38 gram (as per original)                 

1077_2: Standard SOHC (International), OHV or SV Type - Without Standard Norton 'Diamond' Type Oil Holes:

This is the 'standard' roadgoing type Little end, to accept Norton 0.875" Gudgeon Pin piston, with 1.150" width con rod Little End eye, as per the 1077_1 version - however, this Little End bush does not come with the 'Diamond' type oil holes pre-drilled, instead, this type is intended to be pressed in - then the customer can drill the 4 oil holes to exactly match the con rod of their bike.

This was historically the more 'normal'  way of ensuring the 4 oil holes match your con-rod exactly - because you would wait until you had pressed the new bush into position - then use the existing con rod oil holes as a 'guide' for drilling the holes in the bush.  This is great if you are confident in drilling the holes yourself *(and then gently hand scraping the resulting burrs from the bore of the bush), but if you already have the con rod fitted into a crank or engine - you may be worried about the resulting 'swarf' going into the engine - in which case 1077_1 may be easier.  Both types are the same in other respects

- Gudgeon Pin Diameter:  0.875"

- Width: 1.150"

- Oil Holes: Not Drilled - therefore positioning before pressing is less critical, but customer drills oil holes after fitting

- Weight of Little End: 40 gram (this will reduced to 38g after drilling oil holes)       

1077_3: M30/40 or Manx SOHC (and Longstroke DOHC) Type Little End - non-drillled oil holes:

This is the 'Racing' type Little end - as fitted to Longstroke magnesium crankcase racing engines - which like road models used an  0.875" Gudgeon Pin piston, but had a narrower width than roadgoing models - i.e. a 1.010" width con rod Little End eye.  (Again, tolerances may vary on your con rod by +/-10 thou, but the con rod Little End eye width should be approximately 1.00", and the piston similar.

Other vital dimensions for this type of Little End bush are as per 1077_1 and 1077_2 - but for this 'Racing' (Manx) type Little End, the oil holes are not pre-drilled, as racing (Manx) con rods have had slight variations on their oil holes over the years they were fitted.  Therefore the oil holes will need to be drilled by the customer to suit your individual con rod after fitting.  However - as a rule, genuine Lonstroke Manx rods normally had a minimum of two oil holes on the top of the rod - drilled in the centre line.  Because of the reduced width of the Manx conrod Little End eye, the diamond pattern was not used

(note - if you have one of these narrow rods, but with a Diamond oil pattern already drilled - chances are it started life as an Inter Con Rod and has been modified to fit an M30/Manx by a previous owner - not a good idea as it weakens the eye! - I have at least one of these in my collection!)

- Gudgeon Pin Diameter:  0.875"

- Width: 1.010"

- Oil Holes: Not Drilled - To be drilled by customer after pressing to their own con-rod oil hole pattern

- Weight of Little End: 34 gram (this will reduced further once oil holes drilled)       

1077_4: Standard SOHC (International), OHV or SV Type Width - But bored to receive a (non Norton) 0.750* Gudgeon Pin:

Due to the limited availabilty of replacement pistons for Norton single models over the years - it is not unusual for owners to have fitted similar dimension pistons from other Marques to their engines.  One of the most common 'substitute marques' to be used are BSA pistons - which most commonly, are fitted with a smaller diameter 0.750" Gudgeon Pin (i.e. BSA B40, B44 or B50 pistons in 500cc Norton OHV engines, or BSA twin pistons in 350cc Norton singles - all these piston types being fitted with 0.750" Gudgeon Pins).

This variation of Little End bush is to the same vital dimensions as 1077_2 in all other respects, but has a smaller Gudgeon Pin hole of 0.750", in case you have a standard width roadgoing SV.OHV, SOHC con rod - but wish to fit a piston as described above.

As with 1077_2 - the top oil way holes have not been drilled on this Little End Type - it being for the customer to do this after fitting.

Also - it must be remembered that this Little End will be slightly heavier than a standard Norton Little End and may affect the Balance Factor of the engine.  However - this may well be balanced out by the piston - so all piston components and Little End should be compared to the equivelant Norton components to work out if any re-balancing would be preferable  

- Gudgeon Pin Diameter:  0.750"

- Width: 1.150"

- Oil Holes: Not Drilled - customer drills oil holes after fitting

- Weight of Little End: 68 gram (this will reduce slightly after oil holes drilled)       

Price for all 4 variations is - Each.

Email sales@racingvincent.co.uk if you require more technical information on how to remove old Little End bushes, and fit new ones - but it would be expected that anyone attempting this task is familiar with engine build work and has a good understanding of this type of task already - or is trusting the task to an experienced engine builder

These are modern circlips of the same size as fitted to standard Norton pistons - i.e 0.875" gudgeon pins, incase like me you sometimes buy 'New Old Stock' pistons at autojumbles, but the circlips are missing.

However, before fitting, please convince yourself they are a suitable fit and type for your piston, as some pistons require specific circlip types (notably a wire type circlip in a piston with a round groove) - therefore I take no responsibility for you fitting these etc etc. That said, these are good quality circlips, and I will be using them myself when the need arises. This item is for a pack of 4 circlips

We have been asked by 350cc SOHC customers in the last 5 years - if we have any plans to offer a 71mm/350cc version of our Omega slipper type piston?  Well, sorry to say, this is not likely to happen in the near future (this update being March 2021) - as the cost of setup and 'Master' for the original 350cc 'slipper' type Norton Model 40 piston is prohibitive, given the limited number of customers asking for them.  

With all that said - we have been looking at alternatives - and this includes looking at the range of pistons the current owners of the 'Hepolite' piston brand name are now making.  Having spoken to them, and looked at their range of pistons available for other British motorcycles - I have found that they offer a piston (originally to fit a British parallel twin) which has most of the vital dimensions in common with the roadgoing 'lower compression' version of the Model 40 350cc SOHC piston - as shown in the photographs here, with the Hepolite piston 'as supplied' on the left, and an original Norton Model 40 350cc piston (lower road compression - possibly around 7.5:1) on the right.

As you can see, the two most important dimensions are almost identical - this is a 71mm bore piston (the STD bore for a 350 model Inter), and the height from the centre of the Gudgeoon pin to the base of the piston is virtually identical.  There is also a 71mm + 20 thou version offered, although they are not curently in stock (possibly for the duration of Covid lockdown period). Note:  the Hepolite STD piston is actually stamped +40 thou, as the original motorcycle engine they were intended for has a slightly smaller standard bore - but they offer this piston in +40 and +60, which equates to SOHC Model 40 (71mm) STD and +20 sizes.

However there are limitiations to using this piston, which need to be considered and are listed here:

1. Pistons are cast, not forged - their design looks very similar to Hepolite 1950's design with full skirts and milled slot under the ringland.  Therefore I would not recommend them for racing or continued maximum speed work (if anyone still does that on their 350 Inters!).  That said they do look very nicely CNC machined from low expansion silicon alloy - and looking underneath (see photo) - there are casting webs around the Little End area that reach out to the cylinder wall skirt area.

2. They are only available in two 350cc (71mm) Bore sizes - STD and +20 thou:  Sorry, but if you have an engine that is already out at +40 or +60 you would have to consider an alternative, or having your cylinder re-linered.

3. The Gudgeon pin diameter is fractionally smaller than the standard Norton 0.875" diameter: The Gudgeon Pin diameter on these pistons are 0.750", while Norton 350 Gudgeon Pin diameter is the same as the 500cc model - 0.875".  Therefore, if we are to supply this piston, you would need to accept that (and make your own decision if this will affect reliability - although it is highly unlikely - as the BSA B50 piston was often used in 500cc Norton's when available, for racing, but they were fitted with smaller gudgeon pins). Therefore, for anyone wanting to order these pistons, we can also supply a replacement Little End, to fit standard SOHC con-rod, but with a smaller 0.750" internal bore. Incidentally - the weight of the piston complete with Gudgeon Pin, rings, circlips is @355 grams, which is relatively light - so I would imagine the slightly heavier Gudgeon Pin + piston would be comparable to an original Norton 350 piston setup.

4. Con Rod Width:  A Norton 350cc SOHC Model 40 conrod has a 1.200" Little End Width.  The engine these Hepolite pistons were intended for are 1.125" - so the piston will need to be modified by milling an additional 75 thou width into the Gudgeon Pin cast area.  Again - we are looking to supply these pistons with this modification already made, as part of the cost

5.Valve Cutaway: As manufactured by Hepolite, the pistons have the correct crown to gudgeon pin height (the difficult dimension to find), but the valve cutaways are not big enough for 350cc SOHC engines - therefore these would either need to be machined by the customer for their own engine spec, or again - we can mill these for you, to the same specification as the original Norton piston shown in the photograph.

So if you own a SOHC Norton 350cc Model 40 - unfortunately we can supply a forged piston 'off the shelf' - but there is at least a viable option available.  We do have a small stock of these pistons in stock - but have not manufactured new Little Ends yet, or modified the pistons as above. 

If you wish to enquire - either to purchase a piston as supplied by Hepolite, or for a quote for us to modify one as above, then email us on sales@racingvincent.co.uk, - quoting Item 1006 - Hepolite Model 40 piston. 

As at March 2021 - these are Special Order, but would expect the RRP of piston, supplied with modifications to gudgeon pin width, revised valve cutaways and new Phospher Bronze Little End is likely to be @ £220 - £240.

Very nice example of the Norton SOHC exhaust nut, with the correct longer thread that differentiates them from the more common ES2 type.

They are almost exact copies of the original, of the type fitted to most SOHC models, including both M30\M40 International and SOHC (Gardgengate) Manx's.

They are supplied dull plated. To my knowledge they have not been available for many years, and I fit them myself on my own Inter and Manx bikes.

(Note 2021: We are trying to get another batch of these manufactured as now almost out of stock - unfortunately Covid making this difficult.  If they show as out of stock - email us at sales@racingvincent.co.uk when back in stock.  We are also considering having heavyweight spanners lasercut to this finned type of exhaust nut (copied on a spanner I purchased about 30 years ago!, again, email if you wish to reserve one)

This item is for a set of Cylinder Head Sleeve Nut Washers, of the type fitted to most SOHC cast iron cylinder heads (both International and CS1).  

These are CNC manufactured to fine tolerance and in stainless steel.  Price is for matched set of 4 sleeve bolt washers.  

Background and Fitting Information:

These Sleeve Nut Washers are of the slimmer (1/8" thick) type, which was normally fitted to SOHC Cast Iron cylinder heads - under the Sleeve Bolts, and ensured a hard surface for tightening down the sleeve bolts.

Note we also sell the thicker (1/4" thick) type - Item 1015, which were normally fitted to alloy or bi-metal SOHC and DOHC heads - so if you are replacing a set of existing washers on your cylinder (as originals often get chewed), then it is worth checking what thickness your original washers were - as previous owners may have changed the thickness of the washers on your own engine - and changing this thickness will alter the height of the cambox and subsequently, the Oldham Coupling thickness requkired and possibly valve clearance.

Although the later (thicker) type were listed in the 148 Spare Parts Catalog as Norton Part Number 1015 (intended for alloy heads), this slimmer type were normally fitted to Cast Iron heads - but strangely were not shown seperately in Pre-War spare parts catalogs. However, as far as I am aware, most International and CS1 cast iron cylinder heads were fitted with a seperate steel sleeve washer (of 1/8" depth), and if you look at the photograph of the original pre-war cast iron International 500cc head in this listing, you will see that the original sleeve washers are still in place in the two front recesses (which have a full recess all the way round), but have come detached on the rear recesses, as they are open on one side.  But this allows you to see that when our fitted, our washers are the same thickness as the original washers.

As far as I am aware these washers were fitted to all International and CS1 cylinder heads (and probably the early solid bronze racing heads), but if you are replacing your original washers (which often get chewed, and are no longer flat), it is worth checking the width, as previous owners may have replaced them with later thicker washers (our Item 1015) - which will affect the cambox height on re-assembly.

It is very important that when fitting these washers, that a 'matched' set are used - i.e. they must all be the same thickness.  Likewise, your sleevebolts should all be of the same batch and length - as the cambox is placed on top of these 4 supports, and if any of the 4 pillars are of a different length, it risks breaking the rear legs off the cambox casting (the worst issue to have with this engine design).  

We CNC manufacture these Sleevebolt Washers to the standard Norton depth, but also ensure they are checked with a micrometer as a matched set of 4 before packing - they should all be within 1 - 2 thou tolerance of each other.

Final point on fitting - as original iron heads were made for many years (with slight machining variations) - you should double check the width of recess on your original head (particuarly the full recesses at the front) and if you think the new washers are too wide to lightly tap into place - then their outer diameter can be lightly linished by attaching a flap wheel in an electric drill .

Once fitted, you should double check they have all seated properly, by laying the cylinder head down on a flat surface, and using s a depth gauge to ensure each sleeve nut washer is the same height from the base of the cylinder head.  

This item is for a set of Cylinder Head Sleeve Nut Washers, of the thicker (1/4" depth) type fitted to most SOHC (and pre-Featherbed DOHC) Alloy and Bi-Metal cylinder heads (both International and Manx models). 

These are CNC manufactured to fine tolerance and in stainless steel.  Price is for matched set of 4 sleeve bolt washers.  

Background and Fitting Information:

These Sleeve Nut Washers are listed in the 1948 Spare Parts Catalog as Norton Part Number 1015, and were shown fitted to both International (Mod30 and Mod40) and Manx models - and are of the thicker variety, being 1/4" in depth.  However, these were normally only fitted on aluminium or bi-metal (i.e. aluminium with a bronze skull) cylinder heads - and were designed to fit into a bored out recess in the cylinder head vertical stud bores, to provide a hard and level surface for which the Sleeve bolts tighten down onto. 

Although not immediately obvious - earlier SOHC Cast Iron cylinder heads were normally fitted with thinner (1/8" depth) sleeve nut washers in the same location,  which we also offer - Item 1016. 

If you are replacing the sleeve nut washers on an existing engine (which is often because originals become chewed over time) - then it is worth checking what thickness your original washers were - as previous owners may have changed the thickness of your washers and amending this depth will also affect your cambox height and therefore the oldham coupling thickness required.

It is very important that when fitting these washers, that a 'matched' set are used - i.e. they must all be the same thickness.  Likewise, your sleevebolts should all be of the same batch and length - as the cambox is placed on top of these 4 supports, and if any of the 4 pillars are of a different length, it risks breaking the rear legs off the cambox casting (the worst issue to have with this engine design).  

We CNC manufacture these Sleevebolt Washers to the standard Norton depth, but also ensure they are checked with a micrometer as a matched set of 4 before packing - they should all be within 1 - 2 thou tolerance of each other.

Final point on fitting.  I have seen alloy or bi-metal cylinder heads where these spacers will (just) slide in and out, or other cylinder heads where the sleeve bolt wasehers are captive.  We have machined them to the standard width - and as can be seen in the photographs - have been fitted to an original Manx Norton cylinder head from the late 1940's . . . where they slid in.

If you find when fitting these to your own cylinder head - they are a tight fit in, you can decide if you want to warm the head up and use a drift to push them in (ensuring they seat properly at the bottom of the recess) - in which case they will be held captive once the head has cooled, or linish the outside of the spacer washers (possibly with a flap wheel on an electric drill) - so they will fit in without heating (but may annoyingly drop out each time you remove the head to work on it!).   Once fitted, you should double check they have all seated properly, by laying the cylinder head down on a flat surface, and using s a depth gauge to ensure each sleeve nut washer is the same height from the base of the cylinder head.  If they are a tight fit on your head - you must satisfy yourself the tolerances are acceptable before pressing them in - as cylinder heads were made for many years, and tolerances could vary slightly from one head to another.

In the accompanying photographs is also a picture of an original pre-war Racing International (pre-war Manx) bi-metal cylinder head, and this particular cylinder head still has its original sleeve bolt washers held captive in-situ - so they may have originally been pressed in by the factory  (and our spacers have the same dimensions)