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  • RDS129 Runs

    Two weeks to Mallory Park so I needed to fire her up. Sammy Miller kindly let me use his place before it opened to the public and she started easily enough - great. However the museum car park is not big enough to get out of first gear so a bit limiting. Now, I need some advice please:
    1. The GP carburettor is leaking a tiny bit at the bottom i.e. banjo which has two fiber washers and jet holder cover nut which appears to have a no gasket)
    2. Selecting first gear was mostly OK but sometimes it went in with a horrible crunch. The box has been rebuilt by Geoff Nunn so I know it's OK - must be something I'm doing wrong
    3. The front brake, a standard twin leading shoe appears really weak - does it work better when hot i.e. at a proper speed?

    Sammy said the GP carb leak is "normal" and he slackened off my front brake adjuster. Any other suggestions welcome.

  • #2
    Whilst I am not an expert on the Silverstone I would say that a crunch when selecting 1st gear is normal on bikes of the Silverstone era. Its the clutch plates sticking. The normal procedure is to pull in the clutch and use the kick starter to free the clutch before you start the engine. Obviously you have no kick starter so put it in first gear, pull in the clutch and push the bike to free the clutch. There will probably still be a small crunch the first time you start the bike but it should reduce after that and when the engine warms up.
    Regarding the carb, if Sammy says its OK its OK as Sammy has a vast experience of riding and building bikes.
    I must say that I am somewhat concerned that you are to ride the bike for the first time for any distance at Mallory Park, you really do need to take it somewhere, an old airfield or private road to get used to the bike and its handling.

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    • #3
      John, the ride at Mallory is a CRMC event and I am parading only not racing. Anyway, I'll also be running in so I'm not out to get my knee down but rather as you say, getting used to this lightweight as my other bikes are 70s Kawasaki H2 and Z1000. But these both have twin discs so more stopping power than the Silverstone even given their weight. Rene

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      • #4
        I can only say that I don't recall ever having a leak on my GP carbs. Have you been able to ascertain which joint it is leaking from? If it is the banjo seals then it should be easy to fix. The jet cover is brass (I think) and relies on its taper to provide a seal. If you inspect the mating surfaces you might be able to find a burr or scratch which is the cause. I'm not sure, but I think if the float level is set too high that can result in excess fuel leaking too.

        The Silverstone front brake is not the best in the world, but you should get reasonable initial retardation if it is set up correctly so that both leading shoes bite simultaneously. When I say reasonable I don't mean in the same league, or even in the same game as disc brakes. Remember, in the Silverstone's day races were won on corner speed not on braking. It won't get better as it warms up, quite the opposite, as anyone who has experienced bum-clenching brake fade going into Mansfield at Cadwell will tell you.

        I agree with John about the gearbox. If you are still using the Albion clutch that may be the culprit, but even so it should free off as it warms up. I assume you slathered the plates with oil before assembly. Once you get going you won't be engaging first from a standstill anyway.

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        • #5
          Originally posted by 1340fxd View Post
          John, the ride at Mallory is a CRMC event and I am parading only not racing. Anyway, I'll also be running in so I'm not out to get my knee down but rather as you say, getting used to this lightweight as my other bikes are 70s Kawasaki H2 and Z1000. But these both have twin discs so more stopping power than the Silverstone even given their weight. Rene
          Fair doo's Rene, but it would still be a good idea to give the bike a try out before you go to Mallory, OK its only a parade but I assume you will only get a limited number of runs, so you dont want to waste the day (and money) if the bike brakes down. I think you live near Lymington, there is an old airfield at Sway which looks to have enough runway left for testing https://www.google.com/maps/place/Ly...1!4d-1.5419099
          If thats not accessible then may be ask around with any road racing mates, as they probably know of somewhere. Alternatively you could book some track time at a local race circuit, but this is likely to be expensive.
          Last edited by John Wakefield; 16/08/2019, 06:09 PM. Reason: amended text regarding Sway Airfield

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          • #6
            Totally agree and have spoken with local racers - including Sammy and none know of a suitable airfield or similar that is not controlled by the New Forest District Council. I have a biker mate who lives in Suffolk and he has old WW2 sites near to him but here in Lymington all such spaces are controlled. I should get 4 x 15 minute parades over the weekend and the engine and gearbox are freshly rebuilt and she starts and runs well - I'll have to take my chances. Still be nice to fix the fuel leak - thanks for the tip Kevin

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            • #7
              Maybe get the bike road registered a stinger silencer fitted and then ride it on the road. You can ride it when you want then. Thats the big problem with scramblers and road race bikes you can only ride them on a suitable track.

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              • #8
                You're a braver man than me, John. I'd find it very difficult to ride a standard RDS on the road. Foolhardy even.

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                • #9
                  Originally posted by KevinLS View Post
                  You're a braver man than me, John. I'd find it very difficult to ride a standard RDS on the road. Foolhardy even.
                  Should be ok with a bit of detuning, (lower compression and smaller carb) after all the frame is similar to the DC/DD roadster and with a better 2LS front brake. There was of course the Bert Greeves Special 24DDS101 (901JOO) which was reported to have a Silverstone engine all be it the 37A Villiers based engine. A Silverstone on the road would be a bit uncomfortable to ride, particularly long distances, but in essence is little different to cafe racers of the period, and other racers like Manx Nortons have been known to be road registered.
                  Last edited by John Wakefield; 16/08/2019, 08:56 PM.

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                  • #10
                    Lowering compression and fitting a smaller carb would defeat the object of running it to set it up on an airfield or track. A Silverstone on the road is a non starter literally, ok at home on the rollers but my days of bump starting are long gone, if it stalls ....... Also with a GP carb , high gearing and a narrow power band traffic would be a nightmare. Then there is the cost of race rubber and race fuel let alone rebuild costs. So sorry John not practical in my book, better with a bike made for the job if you want to ride on the road. Rene, is there no industrial estates nearby? Sometimes they are private roads and unused at weekends so nobody to annoy with a little noise. Dogsbody

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                    • #11
                      What is going on here? The best place to ride a race bike is on a race track! Mallory Park is perfect Rene; as I am sure you know! Have a good meeting.

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                      • #12
                        Ian. The point I was trying to make is that with there being over 145 Silverstone's still in existence (info from Racer database) very few of these are still actively raced, some (like Rene's RDS129) are being used for parading, but many are stuck in sheds & garages laying idle or in bits.
                        So if some could be 'roadised' it would bring a lot more to life. Yes I realise the Silverstone will not make an ideal road bike, and you would not want to use it to commute or pop into you local supermarket, but it is a 'road' bike and they were raced in the IoM which after all is a road circuit. So with a few mods it could as I said previously have the engine de-tuned (or replaced with a less highly tuned type), ie from a scrambler, keeping the original engine to be refitted if needs be. 'Dogsbody' mentions expensive road race tyres and fuel, but modern road tyres could easily be fitted and with the engine compression reduced it would run on pump fuel. The one big problem would of course be the lack of kick starter, but fitting a scrambles engine would solve that problem, and a suitable 'stinger' added to exhaust should keep the noise down, and help to de-tune the engine.
                        Given these mods the bike would still be good for 80 mph and capable of keeping up with modern traffic. Obviously one would need to chose a suitable riding route away from towns, and there are many good riding routes that are used by modern bikers. see https://www.bestbikingroads.com/moto...united-kingdom
                        So this would avoid having to, as in Rene's case, make a 320 mile round trip for just one hours riding at Mallory, when you could ride every day locally if you wanted at a fraction of the cost and when you wanted.

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                        • #13
                          I would strongly advise against putting a Silverstone on the road. Apart from the obvious - the racket and the lack of a kick-start - the riding position is all wrong and they don't like bumps, potholes etc.

                          I know this from personal experience. Years ago (!) I wanted to run in a new piston on my RCS so I put the 'plates from my Scottish on it and off we went through the lanes. It was absolutely horrid and very hard on the wrists.

                          Mallory's great and Gerrards is a challenge, especially with the bumps on the exit.

                          I have to agree about the drop down to Mansfield at Cadwell - bum-clenching at the best of times, never mind with a dodgy brake!

                          Fitting a Griffon clutch is the answer to gear-crunching. You'd need to find a five-spline one though.
                          Last edited by Colin Sparrow; 17/08/2019, 04:27 PM.
                          Colin Sparrow

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                          • #14
                            Originally posted by Colin Sparrow View Post
                            I put the 'plates from my Scottish on it and off we went through the lanes.
                            Yes we have all done that back in the day Colin (and its not unknown these days as well), the local plod these days would not know a Silverstone from a Scottish anyway, even if they were about, and an APR camera certainly would not

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                            • #15
                              Villiers services do new griffon clutches 5 and 6 spline and compared to what I see s/hand clutches go for good price

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