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  • #31
    Rob, wearing a nuns outfit to often is a disgusting habit, now lets get back to the project...

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    • #32
      Thanks all for the very amusing and off Topic diversions, it certainly helped to take away the attention away from my lack of progress on the project recently. In heating his Shed it seems that Stuart is putting the Winter Fuel payments to good use.
      My next task is to produce a cylinder base gasket/packer! Now the original Villiers part was mild steel, but I am wondering if I should use a similar material or go to Tufnol, as used on the Griffons as it helps to keep the heat from passing to the crankcases? Can anyone advise which, if any, I should plump for?

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      • #33
        Crankcase spacer

        Adrian
        You need to let heat transfer to crankcases. So I advise you to use the steel spacer. The more heat you can disperse from the cylinders the better. As I have said before the finning on the 2T/3T barrels is non existant between the barrels.

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        • #34
          Hi adrian, tough one that, an engine will perform better on cooler damp air, which a tufnell spacer will help create, but at the possible risk of over heating the top end.
          But the barrel temp rising may only be a problem, if it induces seizesure, high barrel temperature is not necessary a bad thing, providing the friction materials can take it.
          I don`t know if there is an inherent problem with the pistons picking up due to hot spots between the barrels, but i would imagine a method of testing to see how hot it really is going to get, is the way to go.
          Its a shame you cannot thin out some of the finning, which may cause problems on some of the damper circuits, the close finning may have served the cooling purpose well on the road, at higher speeds, but i would imagine taking out every other one, will stop clogging & aid better air flow around the top end, on the mx track.
          Radiating the heat out & along the fins is only good when you have plenty of airflow around to remove it. just a thought, dave.

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          • #35
            Originally posted by ADickerson View Post
            Thanks all for the very amusing and off Topic diversions, it certainly helped to take away the attention away from my lack of progress on the project recently. In heating his Shed it seems that Stuart is putting the Winter Fuel payments to good use.
            My next task is to produce a cylinder base gasket/packer! Now the original Villiers part was mild steel, but I am wondering if I should use a similar material or go to Tufnol, as used on the Griffons as it helps to keep the heat from passing to the crankcases? Can anyone advise which, if any, I should plump for?
            If you race in January and February overheating shouldn,t be a problem

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            • #36
              Nice one Stuart, I'd better get a move on then!
              Interesting, if opposing views otherwise and I'm grateful to both contributors for their thoughts. I'd being trying to weigh up the benefits of each but can come to no clear conclusion. So, to assist heat transfer I've resolved to making one from Aluminium, while on the opposite tack I'll make another from Tufnol to see which might have the best effect. I accept there are no fins on either of the inner transfer ports but as the exhaust gases presumably shouldn't penetrate beyond the piston at BDC then each could be cooled by the incoming fresh mixture! I am also aware that the "fresh" mixture might not quite be that, as it will no doubt be a mix of fresh gas and those that have been circulating around the crank for several revolutions previously!
              Now, where's the YAG Laser! Sorry, I mean bandsaw and files.

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              • #37
                Exhaust inspiration for project?

                Notice that there's a 2T engined BSA C15 for sale on e-bay.... Interesting pipes.

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                • #38
                  Interesting what a differencethe base gasket material can make. A local club member in Brisbane has just fitted a tufnol? base gasket/spacer in his Grifon - he had been using, I believe an aluminium one. He took it out to our first club meeting of the year today, temp 31selsius in the shade. Engine seized after a couple of laps. First time I believe. There might be something in top end heat needing to escape through the crankcases.

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                  • #39
                    Originally posted by Mike48 View Post
                    Interesting what a differencethe base gasket material can make. A local club member in Brisbane has just fitted a tufnol? base gasket/spacer in his Grifon - he had been using, I believe an aluminium one. He took it out to our first club meeting of the year today, temp 31selsius in the shade. Engine seized after a couple of laps. First time I believe. There might be something in top end heat needing to escape through the crankcases.
                    Thanks for posting Mike, good to here news of Greeves from Aus. Seizing a Griffon can't be a very pleasant experience. Haven't experienced the same here with mine, even with a Tufnol base gasket. But then again, thankfully, I've never ridden it at 31 degrees in the shade!
                    With all the finning that's available on a Griffon, I think I'd be inclined to suspect another reason for the failure!

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                    • #40
                      Heat dissipation

                      thanks for your comments Dave re your solutions to stop overheating on the barrels they're really appreciated.

                      We have got an alternative solution, there is a nice little german twin engine that has plenty of space between the barrels and with some jiggery pokery we're sure we can get it to fit. We have sourced a heavily tuned version from Druid who has breathed on it, I always wanted an engine to run on pure John Smiths Oops I mean alcohol. it may even be close to matching that rather attractive looking beastie on the front of this months LL
                      Punchy
                      Punchy 336

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                      • #41
                        25SA restoration

                        Punchy,
                        I'm more then happy to breathe on your motor, but only if you supplY the John Smith's or any other alcoholic beverage. Incidentally the tipple of choice is Theakstons "Old Peculiar" which just about sums up the GRA and Pre 65 membership.

                        A BMW twin has got plenty of air space between the barrels.

                        Druid

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                        • #42
                          Nice one druid...hic!..
                          Hi rob, glad to see that you have seen the light & decided to ditch the old lawn mower lump, for something more suited!
                          As for jiggery pokery!, forget it, i have a very large press, its not as subtle, but the results are quicker & quite impressive..

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                          • #43
                            Nice one chaps, but I don't know about letting Druid breathe on my engine, I have enough of a problem getting it through emissions as it is!

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                            • #44
                              Did someone mention emus......

                              Originally posted by ADickerson View Post
                              I have enough of a problem getting it through emissions as it is!
                              You can't say I didn't try to warn you about using emu oil in your premix mate.......

                              Great thread Adrian, and all the best with your interesting project.

                              In the meantime, here's some inspiration (any excuse to post my favourite BGS pic, riding the twin, on here again!)

                              Brian.

                              PS I've heard that Theakstons 'Old Peculiar' fumes are even more volatile when combined with Druid's rolling baccy smoke....!!!
                              Attached Files
                              Last edited by Brian Thompson; 04/03/2012, 01:29 AM. Reason: Pic added.

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                              • #45
                                Good to hear from you Brian and thanks for the picture. Your contributions to the site are always positive, amusing and very welcome.
                                As you rightly observe quite a volatile mix might result from anything that Druid exhales, sufficient to test any MOT diagnostic equipment to the limit I should think. Actually, he's been a little quiet of late, I wonder how he is?

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