- This woven cloth HT lead is of the type originally used on competition BTH magnetos in the 1930's and 1940's, and looks great for the authentic finishing touch on your comeptition bike restoration. Price is per foot. - I use this on my rigid and plunger framed Nortons - Note: Recently a customer informed me that the HT lead got soaked in the rain, and the spark was lost, as it shorted across the cloth. Please can I suggest that if you use the bike in all weathers, you may want to cut back the cloth 10mm on each end where it feeds into the Pickups, to minimise this.

If you have looked at this listing before (i.e. prior to October 2021) you will have seen that we were able to offer a modern reproduction of the original spec KLG ML50 - which had the correct (and now very difficult to find) 18mm 'Long Type' thread, which was 0.750" in length, as was originally fitted to some Norton models (i.e. WD16H Norton and the early Douglas 2 34hp and 3.5hp models).  Unfortunately, these have now all sold and our manufacturer supplier tells us that (partly due to Covid impact) they are not likely to have another batch made, so are now unavailable - sorry.

However, having talked to this spark plug specialist, I am told that there are modern 18mm 'Short Length' spark plugs available (i.e. 0.5" length thread), and these will still work in a cylinder head with 0.750" thread length - and in fact it was quite common for this length plug to be fitted even in period times.  Therefore, we now offer two modern Champion alternatives in this listing - both in 0.5" thread length and will continue to add if other types come available.

We are also looking at the possibility of converting a quantity of 'New Old Stock' KLG WW2 18mm WD aircraft spark plugs (with 0.750" threads) to a suitable motorcycle spec - as they currently have the aircraft style suppression tops.  Email us on sales@racingvincent.co.uk, if interested, we will update this listing at a later date if successful  

Finally, this listing also offers both 14mm and 18mm modern copper/asbestos type crushable washers for spark plugs

 

Spark Plug Types:

 

0896_5 Champion D14 - 0.5" Thread Length.  Normal Running for Side Valve Engines:

These are modern 18mm 0.5" reach plugs, made by reputable manufacturer Champion - and the D14 variant is considered the best choice of grades for a Side Valve engine in normal running condition. As 0.750" reach plugs are now unobtainable - these provide a suitable alternative, and according to our supplier - were often fitted to those engines with an 0.750" length spark plug hole even in period times.  

 

0896_6 Champion D16 - 0.5" Thread Length.  Oily or Rich Running for Side Valve Engines:

These are modern 18mm 0.5" reach plugs, made by reputable manufacturer Champion - and the D16 variant is considered the best choice of grades for a Side Valve engine if your engine runs rich or often oils plugs. As 0.750" reach plugs are now unobtainable - these provide a suitable alternative, and according to our supplier - were often fitted to those engines with an 0.750" length spark plug hole even in period times.  

 For the two plug types above (the same type of plug - but with a fractionally different heat settings - it may be prudent to take one of each type and find which is best for your own engine, if you are not sure which you require.

0896_1 KLG ML50 - 0.75" Thread Length. (Sorry now unobtainable):

For anyone that has searched for the 'Long Reach' (0.750") type 18mm plugs that were fitted to some older (pre-WWII) motorcycles or cars, they will know this longer reach type are now extremely hard to find - most 18mm types now available being a shorter 0.5" inch length - which although can be fitted, can upset the combustion and timing slightly. This type of long reach 18mm plug was of the type fitted to both Douglas 2 3/4hp models (if fitted with 18mm plugs) and some early Norton single cylinder models.   I know this type was fitted to Norton WD16H models - and in the accompanying photographs you can see one of these plugs fitted to an original 1938 manufactured Norton WD16H cylinder head.  I do not have any other earlier Norton 18mm heads myself - but would expect this type of 18mm/0.750" spark plug hole was likely to have been used on earlier Side Valve models and maybe some 1920’s OHV models? . . I expect if you own of these you will know yourself if it requires this type of plug.

Update September 2021 - Very sorry, but our suppliier has now ran out of this plug - and is not expecting to have another batch manufactured (partly due to cost increases post Covid).  I have kept the listing here, in case this changes in the future - and will update it if a new batch are to be manufactured in the future

 

0896_7 KLG RML 60 - 0.75" Thread Length. (Oct 2021 Enquiry Only - but possible special order):

As at October 2021 - we are looking at the option of converting a quantity of 'New Old Stock' WW2 military aircraft KLG spark plugs - which also have the longer 0.750" length spark plug thread, as fitted to the models described above.  As can be seen in the photograph - as originally manufactured they have a special 'aircraft type' suppressor fitting - and will not accept a standard motor cycle style HT Cap.  We are currently looking at re-manufacturing the top of these to fit a motor vehicle style insulator and central core, so they will accept a standard HT Cap or screw on knurled top.  If interested - please email sales@racingvincent.co.uk - but expect the price to reflect the work required to re-manufacture these, and their rarity

 

0896_2/3/4 - Crushable Spark Plug Washers:

If like me, you have numerous 'New Old Stock' spark plugs - but they have lost their original 'copper/asbestos' type washer (with the distinctive copper colour), we can now supply them in both 14mm and 18mm sizes - in packs of six.  The 18mm size have two thicknesses - the wider type being slightly more expensive (and sold as a pair) - but the slimmer 18mm type are still usable and worth keeping some in your toolbox in case you lose one on a run.  You would normally replace these washers each time you remove the spark plug (unlike modern steel spark plug washers) – so it is worth keeping some in your toolkit

Note: Originally these heat resistant 'crushable' type washers were copper with asbestos filling - these modern ones no longer use asbestos - but instead a modern safer filling!

If we find any other modern reproductions of the older style veteran 18mm or 14mm plugs we will add them to this listing - please email us on sales@racingvincent.co.uk if you know of anyone manufacturing them, thanks.

This listing shows a selection of brass fittings for veteran motorcycle spark plugs, as well as some rarer spark plugs and fittings (and a nice copy of the Veteran Lodge style brass cooling fins that fit over most spark plug types).  We have manufactured the knurled brass nuts for securing the HT lead on older motorcycles (i.e. pre spark plug cap) in two main styles and a variety of threads.

Note: see also Item Listing 0896 - since originally starting this multi-item listing, I have now listed our 18mm KLG type spark plugs seperately, along with 18mm/14mm copper abestos type spark plug sealing washers.

 

Spark Plug HT Lead Nipple/Knurled Nut Background:

If you have an older historic motorcycle - i.e. pre WWII or earlier, then you may decide you wish to fit the HT lead to your spark plug with a brass connector, rather than with a more modern HT Spark Plug Cap (of which we also sell in various styles).

Like many old motorcycle enthusiasts, over the years of collecting I have accumulated a selection of old spark plugs of various styles, and some of these go back to the earliest motoring days of the 19'teens - 1920's.  When recently I was looking to fit spark plugs to my own 1919 Douglas 2 3/4hp project bike (used for some of the photos in this listing), I decided to fit period 18mm spark plugs and our ochre coloured cloth/waterproof HT lead, along with veteran style brass HT clip connectors (i.e. pre plug cap) - which would have been correct for a veteran bike.

To go with this I investigated the different style of knurled screw on nuts which were commonly fitted to these early type of plugs, which allow the brass HT connectors to be easily screwed on our taken off.  I was suprised to find there were lots of styles and variations over those early days - but by far the most common type was the knurled adjuster with a design commonly seen fitted to Champion spark plugs.

However, I also have an example of a very pretty Lodge type of knurled nut - which has a wider top knurl diameter and a concave tope.  As well as giving good purchase when tightening the HT lead to the plug - I think this type of knurled is very pretty, and quite rare now.n

Therefore - we have replicated  both these definitive styles - the bigger diameter Lodge type being an almost identical copy of the original nut, while the other small type is copied from an original definitive type used on a 1920's Champion plug (note - I found numerous nuts of this style, many with minor variations over the years - but chose an early type of the most definitive design).

Both knurled nut types are CNC machined in brass by us and can be supplied in a variety of threads - the sub listing items representing the most commonly used spark plug top threads used.  

 

Early Spark Plug Brass Cooling Fin - based on Lodge original, to fit most spark plug types (0895_8):

As you can see in the first photo, in my spark plug collection I have an unusual and very pretty/rare pink Lodge H1S spark plug (New Old Stock), which has the addition of a brass cooling cap with fins, which sits atop the porcelain.  I have seen similar brass cooling fins fitted to the very earliest (i.e. Edwardian) motorcycles and cars and they give a lovely period look to an older motor vehichle restoration.

We have reproduced this finned cooling ring - to an almost identical profile, but underneath, the ring counterbored so that it will fit on top the porcelain of almost any spark plug - including modern plugs.  By so doing, if you wish, you can use modern spark plugs (with make scrubbed off if required!) and this ring placed on top of the porcelain to give the plug a much older and pretty look. 

We offer this cooling ring, along with the knurled 'Lodge' type HT nut (specify which thread type for nut when ordering)  - as shown in the photos associated with this item - including them having been fitted to the KLG 18mm ML50 plugs we also offer here, fitted to my own Douglas 2 3/4hp project.  I have to say, they nicely finish off this area of the restoration.

Spark Plug Top Thread Background:

Until we came to make these knurled HT nuts, I had always assumed the top thread used to hold the HT nipples on spark plugs was a standard thread - standardised on all spark pluge going back to the earliest days - No such luck!

It turns out there were numerous threads used over the years - and I do not think we have found them all!, however I think we have identified the 4 main types (and two seem most commonly used), and have made the two knurled nut styles in sub-types to take into account the different thread types.

I have also gone through my own spark plug colletion and tried to identify the different Makes and Styles that used the different thread types - I cannot be sure that if you have the same spark plug in your collection, it will have the same thread (as they may have changed by year) - but in the accompanying photographs, I have showed some of the plugs with their various thread type in the sub listing to help you select which one is right for your plug.

If not sure - I would suggest you buy one of each (!) . . . but do not try and force on by more than two threads or the brass may strip.  

I cannot be sure this is definitive - but in general I found the following threads used on the following plugs (see photographs that accompany the individual items):

- 8 UNC Thread (0895_1 and 0895_4):  

  - Champion:  I found a number of the older (or US branded?) Champion plugs fitted with this metric 8 UNC Thread.  Those tried with this thread included: Champion N5 (common 14mm 1960's - 1980's plug/ C5 (22mm plug) - both early 1930's rounded ceramic type and later (1960s style multi ridged type) / J10-COM/ L7 (another 14mm 1960s style plug)/ D8C - this last plug is a rare 18mm long reach plug with an unusual extended 3 prong electrode - they are a possible alternative for Douglas 2 3/4hp engines - but you need to ensure electrodes will not fould valves.  I have a pair of 'New old stock' D8 plugs as the on-bike spares. 

  I suspect as Champion was commonly sold in US, that earlier Champion pluges were predominantly this thread - but not entirely, see below in metric threads.

  - KLG:  FE75 14mm plug (1950s style plug?) 

  - Lodge:  Some Lodge threads were UNC, others were metric.  Three of the pink ceramic Lodge plugs I have in my collection were this 8 UNC thread - CANY plug (common 14mm plug), HL14S (pink ceramic 14mm plug - but with earlier seperate hex component for locking in cermaic and H14S with brass cooling fins fitted (this last plug was the one with the big knurled Lodge nut and cooling fins shown in many of the photographs - that we used as a template for 0895_5)

  - Wipac Pacey: F2.0 - blue ceramic 22mm plug

  - AC :  AC 78 22mm plug, made in the USA.  Note, in the accompanying photograph there is a second very similar plug to this, which is also 8 UNC - but has no marking whatsover.  I think this second plug may be another AC or possibly a Bosche make

  - Autolite: In the accmpanying photograph is a 'new old stock' Autolite A652.  Not a common plug - but I believe a 1960's-80's 14mm long reach plug 

- 4mm x 0.70mm Thread (0895_2 and 0895_5):  

    -  NGK: This looks to be the thread adopted by all modern NGK plugs - in case you want to fit a good quality, easily available, modern (14mm) plug  on your old motorcycle, but still use these knurled brass nuts for a period look.  NGK plugs tried included B6ES (common 14mm long reach, including fitted to many british bikes), B9HC and B77HC

  -  Item 0896_1 KLG Plug: Our 18mm KLG ML50 new plugs (Item 896_1) use this metric thread.  Note; as supplied these plugs come with the normal HT cap modern round nut - so if you want to use a knurled nut, they are with this thread

- Original KLG: KLG FE100 14mm plug, which is 'new old stock' and looks to be of 1950's-60's vintage.  Note: this plug looks very similar in appearance to the FE75 plug above, which is UNC - so it looks like KLG at this period used both thread types!

  - Champion:  I found at least one more modern Champion plug fitted with this metric 0.7mm Thread - Champion N62R (1970's-80's racing plug.  I would not be suprised to find more modern Champion plugs also fitted with this metric thread

- Lodge : This is probably the most difficult make of plug to identify thread for - as I found plugs of same 1930's - 1960's (pink ceramic) era with both metric and UNC thread type.  Those found with this 4mm x 0.7mm thread were - RL51 (the famous racing type plugs so favoured on Manx Norton's, 7R's, KTT's etc) / 2HLN / 3HLN

- 3 BA Thread (0895_3 and 0895_6):  

    -  KLG (very early?): I have read that 3 BA thread were fitted to a few spark plugs.  In my own collection I have only found one plug that uses this thread - but it is the very early KLG Brown Mica ceramic type - model number LK1 (the oldest plug in my collection).    It should be noted that a similar KLG plug to this one - the HS1 type was listed as original fitment for Douglas 2 3/4hp models (amd I would be interested in purchasing if you happen to have 2 of these in working order!)

- 4mm x 0.75mm Thread (0895_7):  

  Similar to the 3 BA thread, I have read that the 0.75mm pitch (4mm) thread was also sometimes used on spark plug HT nuts.  In my own collection I have only found one NGK plug (and an obscure one at that!) that uses this thread, but I have made a small quantity of Champion style nuts with this thread, just in case you want one!:

    -  NGK:  I have one older style NGK plug - an unusual C10M (see photo) plug which employs this less well known 0.75mm pitch thread.  It may also have been used on other early NGK or other makes of more modern plugs.  

 

- Other thread types not catered for:  I have one other pluge - an 18mm Lodge from the 20's-30's which has white porcelain and a larger 10 UNF fine thread.  I think  this plug is possibly from a motor car, and the top thread may be intended for a wire style HT top clip, not knurled nut.  I have not made nuts for this obscure plug - but if you know of a this or other threads (with some market!) I may consider making a small batch to htat thread (email our normal sales@racingvincent.co.uk).

Final point.  I am not intending to make any other brass spark plug parts in the near future, but if you believe there is a particular type missed or fitted to early Edwardian or Norton motorcycles - then let me know and we will consider making a batch.

Likewise - with older style spark plugs, we are able to supply a small quantity of the rare KLG 18mm long reach plug (similar to fitted to early Douglas motorcycles and possibly some early Norton engines) - but do not have any plans to supply others.  However, if anyone knows of good quality 18mm long reach plugs still available, we would be interested to hear, thanks 

 

NGK B6ES Spark Plug to fit all Norton road going single engines, i.e. Model 30/40, OHV ES2/Mod 18/Mod19 and SV 16H/Big4.  It also fits Vincent 500cc and 1000cc models (Series B/C/D).  

I use NGK spark plugs on all my bikes now, I have found them to be the best of all modern plugs for quality and reliability.  The B6ES is equivelant to a Champion N5 and is the 'normal' roadgoing fitment for Norton singles and Vincent models.  The other common fitment for these engines was the B7ES (Champion equivelant N4) which is a slightly harder plug and may be more suitable if you prefer harder/hotter running.  I tend to keep at least one of each in my tool roll on road bikes, as spares - we sell the B7ES grade as well - Item no 0576

NGK B7ES Spark Plug to fit all Norton road going single engines, i.e. Model 30/40, OHV ES2/Mod 18/Mod19 and SV 16H/Big4.  It also fits Vincent 500cc and 1000cc models (Series B/C/D).  

I use NGK spark plugs on all my bikes now, I have found them to be the best of all modern plugs for quality and reliability.  The B7ES is equivelant to a Champion N4 and is an alternative to the slightly softer B6ES (item number 0575). You may find your engine runs slighlty better on this grade of plug if you often run at high speeds or your engine runs hot, as this is a slightly harder (colder) plug.

I tend to keep at least one of each in my tool roll on road bikes, as spares - we sell the softer B6ES grade as well - Item no 0575

- Standard black rubber HT spark plug cap. Suppressed

Classic 'Champion' spark plug cap, Type WCX600, with suppressor fitted.  A very popular classic model of HT spark plug cap, fitted to many british bikes in the 50's-60's.   

- NGK Modern LB05F spark plug cap with rubber shrouds - Black finish. - I have found NGK the best and most reliable spark plugs caps you can get , and have been using this type on my road bikes for the last 20 years - they are without doubt the best value for money spark plug cap available and include waterproofing covers. If you are not worried about about ultimate originality then these are the ones to go for!

- NGK Modern LB05F spark plug cap with rubber shrouds - Red finish. - I have found NGK the best and most reliable spark plugs caps you can get , and have been using this type on my road bikes for the last 20 years - they are without doubt the best value for money spark plug cap available and include waterproofing covers. If you are not worried about about ultimate originality then these are the ones to go for!

NGK modern LB05EMH competition spark plug caps with resistor to protect against RFI interference - Waterproof and probably the best cap you can use if you are using the bike seriously - but not cheap!

I also include the small nylon tie band clip that NGK used to suppliy with this spark plug cap themselves - but stopped supplying themselves some years ago!  (we also sell the cable ties seperately Item 1204).

I used to use this type of spark plug cap on my own racing bikes, running on methanol

Oct 2023: Now back in stock, after a long time of them being unavailable - but now quite difficult to get.