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  • Res 122

    Just started the renovation of RES 122.
    After the last 40 years dealing with Yamaha TZs (still have a 1974 TZ250 A) I'm getting my head back round imperial size threads etc.
    As the price of replacement BSF bolts is silly money for what I am buying the stand alone bolts/nuts are going to be UNF, much more availability and cheaper prices.
    I was replacing the GP5 carb with a 36mm Mikuni, which I have purchased as per Stan Nicholsons' data from Motocarb, but I have managed to get a new #3 slide from Austria along with other parts from Amal and Autocycle engineering on ebay so I'll persevere with the GP for now. My 24RDS ran OK back in 1971 with one but then it was 50 years younger, even I worked properly back then.
    Autocycleengineering are selling up so their stock is listed, buy now regret later.
    The ignition from Electrexworld has just arrives as some of the original Steffa is missing - the spark - just as original.
    Frame stripped down and ready for blasting and paint.
    I seem to have 2 rev counters, the one mounted in the fairing sweeps clockwise and the spare (with anti-vibration mount) sweeps anti clockwise, both x4 and the anticlock one reads OK when driven with a drill in the conventional rotation direction.
    Can't get the Heidenau tyres I want in this country at present so I might have to source them from Holland. I think I shall have to cut the old Michelin S41 tyres to get them off. They are PZ4 soft compound but seemed not to have aged well.
    Still this all keeps me off the street and out of the pub so it must be doing some good.
    Last edited by tonyed27; 15/11/2022, 11:06 AM.

  • #2
    Might be a good idea to say where you are I am in West Yorks. and have turned up a few odds and ends for Ian B;s RES Peter.

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    • #3
      I have included my location on the racer database but that entry has yet to filter through. I am located just north of Littleport, which in turn is just north of Ely which is just north of Cambridge.
      Littleport being the birthplace of William Harley the father of William S Harley the co-founder of Harley-Davidson like Invacar another manufacturer of vehicles for the disabled, however in my opinion they are the 'mentally' disabled.
      Having said that back when, It must have been late September (and a Rod Stewart once sung, I should've really been back at school) I had a few laps round Snetterton, the old Snetterton with the Norwich straight, on the ex-Renzo Pasolini works XR 750. Quite a machine and I would hazard a guess a lot better then the monstrous 'baggers' that Muckspreader and co have been campaigning in the US of late.
      I have only ever seen one race I would consider as l more stupid. One Saturday I arrived at Mallory for a Sunday national race to see a visual experience of the absurd - Caravan racing. I was expecting a queue of irate touring car racers bulked up behind swearing for the things to 'get of the bl**dy road you aholes'. Then one went into a violent weave down the Stebbe straight to trash itself and presumably the towing vehicle is a mass of splinters and cooking wear. Well laugh, I nearly drank my own beer.

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      • #4
        tonyed27 Unfortunately the Racer Database is not being maintained at present, the web master appears to have gone awol but hopefully it will get up dated when a new web master is appointed. I am maintaining a private version of the Silverstone/Ulton database as part of the Greeves Survivors Register and have updated your bike (and others on that)

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        • #5
          Hopefully Ian is only temporarily AWOL!!

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          • #6
            From the darker corners of my mind thinking back to 1973 when I last had a Silverstone, as there is no head gasket I seem to remember having to lap the head/cylinder joint using very fine grinding paste to ensure a gas tight seal. Am I right or what?

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            • #7
              Tony, yes you are correct in your memory of lapping the head and barrel. However I did have one engine with a copper head gasket, I assume someone had skimmed a head and needed to drop the compression. Worth measuring the volume at TDC.

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              • #8
                Thanks. Can't be 1000% sure but i seem to remember just using solvol metal polish until a nice polished ring appeared all round.

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                • #9
                  Fine grinding paste and a big piece of plate glass, both srfaces with matt finish and a thin smear of Three bond on assembly works for me.

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                  • #10
                    I am not sure about the RES but I know there is a 1/32” compression plate that fits between the head and barrel in the RDS parts list, that is required to drop the compression ratio on the road racers. When I first raced my RDS in 1982 it seized every time I took it out on the track, whatever I did with the jetting. After I came across the article reprinted from Motor Cycle of 20 August, 1964 in Derek Picard’s book describing the “new” Greeves engine for the Challengers and the RBS it explained that the compression ratio had to be lower on the road racers than the scrambles bikes as they are run for longer periods at full throttle and hence run hotter. As the cylinders are the same length the compression plate was required to drop the compression ratio.

                    I bought the compression plate from Frank Conley and, presto, it stopped seizing. The only time I have tightened up the piston is going out on the track without the engine being thoroughly warmed up, causing a cold seizure.

                    It also describes setting up the cylinder base gaskets to provide a .065”-.075” measurement from the top of the cylinder to the top of the piston at TDC, with the cylinder torqued to specification. Squish was obviously not a consideration

                    Stan

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                    • #11
                      OK I give up - what thread are the front and rear brake cam nuts (NBW 86) in the parts book?

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                      • #12
                        Originally posted by tonyed27 View Post
                        OK I give up - what thread are the front and rear brake cam nuts (NBW 86) in the parts book?
                        British hub use UNF, spanner size should be the clue.

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                        • #13
                          The nuts are 5/16 cycle thread if you can’t find any they are available from British.bikes1970

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                          • #14
                            Cheers - plenty on ebay. About the only thread form I hadn't tried. M8 x 1.00mm nearly fitted as they are 25 tpi as opposed to 26 tpi for cycle thread.

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                            • #15
                              I now have the Silverstone as a 'flat pack' kit - some home assembly required.

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