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RDS 129 is finally finished

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  • RDS 129 is finally finished

    Here is my 1966 RDS 129, finally ready to start up and confirmed to parade at CRMC Mallory Park at the end of August.

    Now, I have never worked with an AMAL 5GP2 carburettor. What exactly does the air valve do - is it used for starting? Also I have fitted new Main jet (420) new Pilot jet (25) and new Needle jet (109). What is the adjustable screw on the right hand side opposite the pilot jet?

  • #2
    That looks really nice, thanks for posting the pics. I like the way you've mounted the shark fin, I've been struggling to work out a decent way of doing that without welding a bracket onto the swinging arm.

    With respect to the GP carb, please bear in mind that my information comes from memory of what I did nearly forty years ago and a few notes I have from that time. The screw you are referring to is the pilot air screw. As its name suggests it regulates air, therefore screwing it in richens the mixture. I'm going to suggest a starting point of about 1 1/2 turns from fully in. In my experience this setting mainly affects pick up on starting. With the engine warm and running at low revs, blip the throttle and adjust the screw until you get a clean pick up. In the old days of push starts it was important to get this right and it could make a real difference to how quickly you got off the line. Once it is adjusted you'll probably rarely have to touch it again.

    The air valve is kind of interesting, I think its main purpose was to ease cold starting, but I never used it on my Greeves, it was disconnected and removed However, when I was racing a Formula Bantam with a TT carb on a circuit with a long straight (particularly the old Norwich straight at Snetterton or the back straight at Cadwell) you could check the main jet size by slowly closing the valve while at full chat until the engine just started to four stroke. The aim was to get the engine to four stroke at about the halfway position of the valve, then open it a little. If the engine wouldn't four stroke with the valve fully closed then you knew for certain that your main jet wasn't big enough. That was OK on a Bantam on a long circuit, but things always seemed a bit too busy to fiddle around like that when racing the Silverstone at somewhere like Lydden Hill.

    Anyway, good luck with sorting it out, have you started it at all yet?


    • #3
      Lovely, Im getting ready to restore RDS 130.


      • #4
        Kevin, many thanks for the carburettor tips - very useful. If you like I can let you have the dimensions for the shark fin bracket which I made using 40 year unused welding skills - not pretty but appears to work! Willie, what state is it in and do you know much of the history? Rene


        • #5
          Hi Rene, RDS 130 has had only one owner till I got my grubby hands on it a few months ago. The "rolling chassis" is fine with slight surface rust. The clutch is fossilised and the crank journals are rusty. Im off up to "Norn Iron" tomorrow to a big classic show so hopefully I get to meet someone who may be able to advise me.


          • #6

            Good luck with the restoration, mine are going very slowly mainly because I'm trying to build a house at the same time and the bikes need a fair bit of machining done. I took a bunch of old crank parts to Simon Bateman, most of which I thought were past redemption, but he managed to salvage enough for two complete cranks for me with new pins and bearings. If all else fails he has a solution by re-working the shafts and cases to take oversize bearings. You might want to try him, he is good.

            Are you using the Albion clutch or Griffon. If you don't mind spending a bob or two the Griffon clutches can still be had new and are well worth the expense. I still have a box full of Albion clutch parts if you need anything.


            I'll probably go to the CMRC meeting at Mallory, so I can see how you've done it there.


            • #7
              Well I had some luck on Saturday, met a man who is going to sell me a Griffon clutch and had an interesting chat with a man who told me a Honda CR 250 crank can be fitted with some modification. Thats not a path I will follow as I only intend to do parade laps. Roughly how much is a new Griffon clutch and where would I buy one? Ta, W.


              • #8
                TDS have them on their website at £380, I don't know how up to date that is though.


                • #9
                  Thanks for that info.


                  • #10
                    Rene, it's interesting to see your RDS has the same Griffon style, primary chain covers as my Silverstone, with provision for the tach drive from the end of the crankshaft, blanked off in your case. I am still running an original Smiths magnetic tach on my bike so use that drive. All the pictures of Silverstones seem to have the 2 bolt arrangement for the primary covers, up to the RES, so the covers that you and I have must have been made specifically for the road racers because of the provision for the tach drive, but were these available after production of the Silverstones stopped?
                    As far as I know my bike was not raced after the early 70s and I bought it and imported it from the UK in late 81, so was this cover fitted back in 66 when the bike was first built, by Peter Williams I believe?


                    • #11
                      Stan, this is how the bike came and I am no expert. Maybe Dogsbody can throw some light on this subject? I have looked through my books including "British 250 Racer" but there is not much to see thanks to the full-fairing! I am intrigued by your reference to Peter Williams - who was he please?


                      • #12
                        Iím not sure whether they changed to that case for the RDS or the RES, but certainly thatís the case my RDS has, although it may be a retrofit. Whatís interesting about the pic is that the bottom fin had to be shortened on my barrel to allow the chain case inner to fit, but it looks like your barrel is unmolested. Iím not sure how that can be.


                        • #13
                          Kevin, Looking at the parts list for the RDS it has an earlier part number for the chaincase inner and outer cover than the RES, also only three clutch plates, so yours must be retrofit. The same applies to my RCS, that having the rear of the bottom fin on the barrel cut back to clear the chaincase. I had assumed it being the last RCS it was made with the 5 speed cam barrel box originally. Rene, Peter Williams was the Norton development engineer and also a top rider until his career was cut short by an accident at Oulton Park. Dogsbody


                          • #14
                            Further to Dogsbody's note about Peter Williams, in his book "Designed to Race" he describes modifying a Silverstone to fit the Orpin supplied water cooled cylinder and LE Velocette radiator in early 1966, lowering the rear subframe and changing the footrest position and also the clip-ons to give a better riding position. This is the bike shown on page 47 of Pickard's book. I have a copy of the complete article from the Morton's archives and that includes a second photo of the bike from above with the tank removed. Peter worked at Greeves at the time as a draughtsman and rode an Orpin entered Silverstone to 3rd place in the 1965 Manx Grand Prix behind the winner, Denis Craine also on an Orpin entered Silverstone.

                            Peter crashed this bike late in 1966 at Snetterton and, according to the late Chris Goodfellow, it was rebuilt with an air-cooled cylinder and standard head, Orpin taking back the "prototype" water-cooled cylinder. This cylinder eventually went to New Zealand where it is still believed to reside.

                            This is the bike I believe I bought in 1981 as the frame, footrest mounts, etc. are identical to the photos of the bike featured in the Racing Line article originally published in Motor Cycle in April 21, 1966. Although it sounds from the article that Orpin did all the modifications, Peter says in his book that Orpin supplied an "old" Silverstone and the modified parts for him to build the bike as he had already entered a few early season races after being promised a new Silverstone for the 1966 season, but as none was forthcoming at the time, he built this bike at Greeves. As records show, the first RDSs were shipped in May of that year, well into the racing season. Incidentally, Peter won the first race he rode this bike, at Brands in early May, and photos of him at that event rounding Druids have been shown in several books, including the Carrick/Walker Greeves book.

                            Enter Peter Williams Motorcycles on Google to get a look at his career and what he is currently working on.



                            • #15
                              Stan, I was talking to Peter at our local classic bike show last year about his days working at Greeves and he said he felt guilty in the end because they didn't give him much to do and he sat around all day and just claimed his pay! Mainly as a result of this he left as he didn't think what he was doing (or not doing!) was fair to Greeves!