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Dad's 380 Griffon project, 30 years and counting!

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  • Dad's 380 Griffon project, 30 years and counting!

    I think Dad bought his 380 Griffon in 1988, as I found some pictures of it on a trailer outside our old house. When I was little I remember moving the chassis around during one of his garage 'tidy ups', any feelings of being a grown-up now - based on the fact I could move a full-size bike around on my own - dashed when I noticed that the engine was missing!!

    The engine did arrive with the bike, it was complete as bought. Dad talked about having the engine rebuilt a long time ago by Mike Palmer. Well finally I found the bottom-end, indeed looking pristine. I think it was likely done about 30 years ago. The rest of the bike has languished since - one of many projects that, alas, the old man didn't finish.

    My focus at the moment is on rebuilding Dad's Bultaco, but as there are limitations on what I can do/go shopping for/people I can pester for help, I'm doing bits on the Griffon too.

    So first of all it was to round up the engine parts, including the gearbox (in bits in a cardboard box looking a bit sorry for itself, now wrapped up and in due course will be sent off to Geoff Nunn).

    As mentioned the bottom-end is done. But what about the cylinder barrel and head? Well...

    Click image for larger version  Name:	DSCF6720P.jpg Views:	0 Size:	224.6 KB ID:	80819

    I'm sure it looked better when it was put away at the back of a shelf. But then the mice moved in - I expect the twin exhaust ports made for quite a luxury residence. I'm guessing though that the sanitation arrangements weren't ideal because the bore is in a bit of a mess.

    I started with scraping out the remains of the nest - not looking much better:

    Click image for larger version  Name:	DSCF6725P.jpg Views:	0 Size:	189.0 KB ID:	80820

    Next I went to work on the rust, using a large piece of alloy bar to gently scrape at the mess.

    The next two photos show how it looks close up, and then secondly that it is responding to some careful work with wire wool. But I have some questions...

    Click image for larger version  Name:	DSCF6802P.jpg Views:	0 Size:	198.9 KB ID:	80821

    Click image for larger version  Name:	DSCF6796P.jpg Views:	0 Size:	168.7 KB ID:	80822


    The wire wool is messy, and I was wondering if - being steel - it can interfere with the liner? Could I use an aluminium or other wire brush on a dremel or flexible drive? Or does anyone have any other suggestions?

    I'm guessing it might be a bit far gone to get away with a clean and hone. I did a rough measurement (can't find a bore gauge big enough) and it seems to be +0.040. This would make sense as there's a new +0.040 piston here for it. So presumably the bore was in good enough shape when it went on the shelf. Do 380 barrels go a size higher, or is that as big as you can get away with?

    And finally, would it have been matt black originally?


  • #2
    You could make up a honing tool, turn a piece of wood a bit smaller than the bore, cut a slot in it and wrap a piece of emery cloth round it, mount it on a spindle (long wood screw with head cut off would do, and then run it up and down the bore with an electric drill. You will then see how bad pitting is, if its bad than its a rebore. I am told that some pitting on a 2 stroke is good as it holds oil.

    Comment


    • #3
      I do have a honing tool here, although it's not got much left on it. How abrasive is it, or rather is there any chance it'll add wear to the bore beyond the rust?

      Comment


      • #4
        Originally posted by Ian View Post
        How abrasive is it, or rather is there any chance it'll add wear to the bore beyond the rust?
        Depends upon what grade of emery cloth you use, if you use a fairly fine grade it wont unduly wear the bore, but if its that rusty that it wont clean up with a short application the bore has had it anyway

        Comment


        • #5
          Ian, if you have a 3 stone cylinder hone replacement stones are available in different grades of abrasion, or at least they are here in Canada, not sure in the UK. If you use a variable speed drill and plenty of honing oil on the stones the bore should clean up to allow a better look to see if there are any divots produced by the mouse urine. Use as slow a speed as possible and be careful to keep the stones in the bore, oh, and I back off the spring pressure to reduce the rate of material removal but that is just to remove the glaze, you might need a bit more to remove the rust. I don't think small rust pitting should affect its use. I don't know what the piston clearance is for this size piston, I use .0045" on the Silverstone. The easiest way to check this if you don't have a suitable bore gauge is to put the piston on the unworn portion of the bore, not a problem if the motor hasn't been used since the rebore, and check the clearance with feeler gauges. Remember the piston is oval as well as tapered so check the clearance at the bottom of the skirt at right angles to the wrist pin (sorry gudgeon pin).

          Stan

          Comment


          • #6
            Hi Stan, thanks for the advice.

            I do have a cylinder hone as described, and started today, but one of the stones was almost worn out so I ordered new ones today - so for a few days that's on hold. I did start making some progress, there are definitely some marks but I don't know if they're in the metal or in the glaze. I think it needs some more work yet.

            I know there's a bore gauge here somewhere for the smaller cylinders (66mm etc) but not sure about the 80+ ones. Almost certainly we have one. I will get the bore looking reasonable and then see what it measures up at. And yes good idea to use the piston with a feeler gauge, I can also do that.

            I'm not sure if the Griffon can go up to +0.060 or if it'd be new liner time. It's a big shame the mice moved in because there were a couple of other cylinders on the same shelf and they're fine. I guess they chose the most spacious apartment of them all ; )

            Comment


            • #7
              Originally posted by Ian View Post
              I think Dad bought his 380 Griffon in 1988, as I found some pictures of it on a trailer outside our old house. When I was little I remember moving the chassis around during one of his garage 'tidy ups', any feelings of being a grown-up now - based on the fact I could move a full-size bike around on my own - dashed when I noticed that the engine was missing!!

              The engine did arrive with the bike, it was complete as bought. Dad talked about having the engine rebuilt a long time ago by Mike Palmer. Well finally I found the bottom-end, indeed looking pristine. I think it was likely done about 30 years ago. The rest of the bike has languished since - one of many projects that, alas, the old man didn't finish.

              My focus at the moment is on rebuilding Dad's Bultaco, but as there are limitations on what I can do/go shopping for/people I can pester for help, I'm doing bits on the Griffon too.

              So first of all it was to round up the engine parts, including the gearbox (in bits in a cardboard box looking a bit sorry for itself, now wrapped up and in due course will be sent off to Geoff Nunn).

              As mentioned the bottom-end is done. But what about the cylinder barrel and head? Well...

              Click image for larger version Name:	DSCF6720P.jpg Views:	0 Size:	224.6 KB ID:	80819

              I'm sure it looked better when it was put away at the back of a shelf. But then the mice moved in - I expect the twin exhaust ports made for quite a luxury residence. I'm guessing though that the sanitation arrangements weren't ideal because the bore is in a bit of a mess.

              I started with scraping out the remains of the nest - not looking much better:

              Click image for larger version Name:	DSCF6725P.jpg Views:	0 Size:	189.0 KB ID:	80820

              Next I went to work on the rust, using a large piece of alloy bar to gently scrape at the mess.

              The next two photos show how it looks close up, and then secondly that it is responding to some careful work with wire wool. But I have some questions...

              Click image for larger version Name:	DSCF6802P.jpg Views:	0 Size:	198.9 KB ID:	80821

              Click image for larger version Name:	DSCF6796P.jpg Views:	0 Size:	168.7 KB ID:	80822


              The wire wool is messy, and I was wondering if - being steel - it can interfere with the liner? Could I use an aluminium or other wire brush on a dremel or flexible drive? Or does anyone have any other suggestions?

              I'm guessing it might be a bit far gone to get away with a clean and hone. I did a rough measurement (can't find a bore gauge big enough) and it seems to be +0.040. This would make sense as there's a new +0.040 piston here for it. So presumably the bore was in good enough shape when it went on the shelf. Do 380 barrels go a size higher, or is that as big as you can get away with?

              And finally, would it have been matt black originally?
              Ian good to see you working on the 380 Griffon . Oversize GriffonPistons go up to +60
              there is still more meat on the liner for a much bigger piston . As an example my Griffon QUB has an 84mm Maico piston in it which would be +80. So you have plenty of options either standard or trick to get your dads 380 going .
              happy to help in any way I can . Rob was always very helpful with my bikes ... even welding my QUB footrest in the paddock by the shed ...: and we always had a little ride around the paddock afterwards to “mow” the grass
              cheers Kim

              Comment


              • #8
                Thanks Kim. I have worked it with the honing tool a little and will give it another go. Looks to be a fair bit of putting but good to know the liner is good for a few more sizes.

                At the moment the Griffon is on the back burner as I have a few other jobs to do, but once the country gets back to life I will see about having the barrel cleaned up (Villiers Services?) and getting the gearbox bits off to Geoff. Meanwhile I am doing some experiments with paint spraying, so once I am confident I can do the cycle parts justice the frame etc will get done.

                Comment


                • #9
                  Hi Ian
                  great stuff !
                  Mechanicals you could also go to Sam and Andy Heitman at Boretech just down the road from your dads place .... they will look after you

                  Comment

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