10RN Throttle Slide/Needle Holder to fit Original Amal 10RN Carbs - 5 and 6 Cutaway's Avail (Each)

Product no.: 0961 RN134/107

In stock

Recommended Retail Price, plus delivery

'Remote Needle' type throttle slide and needle holder to fit original Amal 10RN (Remote Needle) type racing carburetter - these been original fitment on most 1937 onwards SOHC (and pre-1953 DOHC)  M30/M40 and Manx models.  Amal RN carbs were also fitted to many other period competition and 'Grand Prix' spec motorcycles - i.e. KTT Velo's and similar.

For Norton Single M30, M40 and Manx Models, the following slide fittings were most normal:

- 500cc Manx and M30 Models: No6 RN Slide (LH type - whcih these are) 

- 350cc Manx and M40 Models: No5 RN Slide (LH type - whcih these are) 


Background and Manufacturing Information:

As can be seen from the photograph's - these slides are actually based on the similar Amal TT slide design, but the slides for Amal RN carb has an additional threaded hole and slight countersink, to hold a special milled brass sidebar, which holds the throttle needle in a seperate chamber alongside the main carb body - which helps reduce the obstruction of air into the engine.

We have the main slides made to the same specification as our TT slides (see Item 0143), but for these we have the addition of a threaded hole in the top face of the slide.  We also have the special RN throttle needle holder manufactured identical to the original design - and original Amal RN needle holder being used as the pattern - these are CNC milled from billet Brass.

Original Amal RN slides used a flush fitting brass screw to fix the throttle needle holder to the slide - but they also had the threaded shaft of the screw 'mushroomed' underneath, and the holder soldered to the slide - once fitted.  Both of these features were to ensure the throttle needle holder did not vibrate loose in service.  As you can see from the accompanying photos - we have made jigs that allow both of these steps to be carried out - and once completed each slide is test fitted on both an original Amal RN inner block and a virtually new (old stock) brass bodied RN Carb body - to ensure smooth operation.

Note: that as part of this necessary manufacturing process - because we have the TT and RN slides 'flash plated' (to stop corrosion of the slide) first - we carefully remove the nickel plating in the area on top of the throttle slide, where the needle holder is to be fixed - to ensure the best possible contact for the solder.  This is purely cosmetic - and necessary to ensure proper solder flow.   

Stocks of this type of slide are limited, so if you need one, we can only advise you order one quite soon . . . as once this batch have gone, it will be at least 12 - 18 months until we makle a further batch - as you can see from the accompanyning photographs - on top of the normal 'TT Slide' manufacturing processes - there are a number of other processes required - speciific to the original Amal RN slide design - which we follow as faithfully as possible.  


Amal RN (and slide/needle design) Background Information:

As far as I am aware the Amal RN carburettor was introduced in the mid/late 1930's purely for competition motorcycles - in an effort to give a less obstructed airflow through the inlet tract - not unlike the Amal Type 27 needless dirt track carburettor (which I used to have fitted to my old Rotrax JAP speedway bike - and was good for full bore, but not much good for any kind of cutover or slow running).  To do this it moved the needle position from in the centre of the main choke area/inlet tract to the side of the carb.  From what I can gather, it had a reputation for being a better carburettor on long GP circuits such as the Isle of Man or Spa (etc), but was a bit more 'fussy' for slow or mid range running on roadgoing sports bikes, which were normally fitted with Amal TT carbs.

What I do remember as a teenager in the 1970's and 1980's - just starting vintage racing at the time, was that the RN carburettor was not considered as desirable as the TT carburettor for fitting to historic race bikes for VMCC (short circuit) racing, as they were considered less flexible - but really I am not sure if this was true or not.  What was probably far more true was that as the slide got worn and let air bypass - it was less easy to find a replacement slide, so more of them were worn.  I think because of this they were often overlooked. .  . and probably many of them thrown away - making them far less common and hard to find today!

I only remember fitting an Amal RN to one of my Norton's once, and that was back to back with a similar bore/condition Amal TT - both setup for methanol.  If I remember correctly - I could not tell any discernable difference between the two.

Those originally fitted to M30/M40 and early Manx Norton models were of the 'Long Neck' variety (as in the accompanyning photograph - note the inlet tract mounting flange extends past the lower slow running adjuster by approximately 1 inch, while 'normal neck' type carbs have the flange abutting this carb and are shorter.  Therefore, this 'Long Neck' variety are (not suprisingly) considered the most desirable and difficult to find.  However, it is possible to fit short neck type - but it is normal to fit a 1" alloy spacer to restore the full Norton inlet tract length.

Please note if you have a worn RN slide and are intending to try and remove the special throttle needle holder, to re-use it on a new TT type slide - the original fitment of this adaptor is not as straight forward as it looks.  Original slides had ths special needle holder lightly soldered to the throttle slide, and the screw riveted underneath . . . trying to remove that part from an original worn slide will normally damage both the slide and the original slide - we do also sell the throttle needle holder and correct screw seperately - Item No 0962

Customers who bought this product also bought

Recommended Retail Price, plus delivery

Browse these categories as well: 2.a Parts to fit: Original Amal TT Competition Carburettors, 2.b Parts to fit: Original Amal Remote Needle (RN) Competition Carburettors