High quality throttle slide and throttle needle adaptop to fit original Amal 10RN and T10RN Carburetter - hoping to be available in Spring 2021. Email us on email@example.com if you wish to reserve one
These slides are identical to original throttle slides and are very similar to the throttle slide fitted to original Amal TT carburettors.
However, just like the original Amal RN design (which stood for Remote Needle) - the slide has additional machining to allow the affixing of a seperate milled piece, that held the RN throttle needle in the seperate needle chamber which was particular to this type of carburettor.
Update December 2020: As far as we are aware - this type of slide have been unavailable since the original Amal factory stopped making spares for them (which we assume was in the late 1950's or 1960's). Although the slide itself is the same as the TT slide, the special needle holder is very difficult to reproduce because of the unusual shape, but we have recently had a batch of these adapters CNC milled from brass billet. We are in the process of having a batch of TT like slides manufactured and some of these will have the additional machining steps made to them to turn them into RN slides.
Stocks of this type of slide will be limited, so if you wish to reserve one then email us on our normal firstname.lastname@example.org, stating which cutaway or model you wish to fit it to. We will not know final pricing until fully manufactured, but we expect the slides and adaptor to be fully ground and nickel plated as per the originals and the adaptor to be fixed to the slide as per originals.
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. It looks like they are just held to the slide with a small screw at the top of the slide - however, do not try to undo this screw without first checking underneath, as normally they look to have had the tip of the thread of the screw hit with a punch into a small countersink in the slide - to stop the screw becoming unscrewed in use. If you try to remove the screw without first carefully