Hi
I just stopped down my a65 head and while pressure cleaning I didn't notice after taking off the valve springs that there were copper washers under the spring cups I only found two does anyone know which valve they go under and are they required
Also what's the difference between the pre 66 gear box mainshaft High gear bush , I've acquired a gearbox and I want the rebuild it but not sure what year it is and need to put it in my a65L 1970 cases
Hi,
They are not normally fitted, maybe worth investigating why they were there, maybe the wrong cups have been used.
The pre 1966 bush is one piece, pt no. 68-3026, it changed to two pieces, 2 x pt no. 68-3178.
Best wishes...
If the washers are actually thin shims they may be there because a previous owner had shimmed the springs to the specified fitted length.
Yes pretty strange, not in the parts book anyway
Yes the Bush is defiantly two bushes but not sure what year as the camplate has a strength net on top and a 1970 one does not?
If they are shims they will not be in the parts books, it would have been something a previous owner had done to restore sping fitted length.
Quote from: JulianS on 03 Jul, 2020, 09:40
If the washers are actually thin shims they may be there because a previous owner had shimmed the springs to the specified fitted length.
Not so much for the length but often done to achieve a desired spring pressure.
Quote from: JulianS on 03 Jul, 2020, 12:58
If they are shims they will not be in the parts books, it would have been something a previous owner had done to restore sping fitted length.
I've never seen shims listed either, but its often done when racing.
Quote from: spike123 on 03 Jul, 2020, 12:13
Yes the Bush is defiantly two bushes but not sure what year as the camplate has a strength net on top and a 1970 one does not?
The 1970 cases don't have the relief for the bracing piece on the cam plate (Dave Brady did a post on this a few months ago) you can adjust the cases to fit or fit a 1970 cam plate which is improved over the earlier types.
The change to 2 bushes came as a mid season change for 1965 models, too late for the 1965 parts book, and is on parts bulletin G31 dated March 1965.
Well if the 1970 camplate fits ok I'll get one off those
Hi,
The last cam plate that has no strengthening piece is actually a bit thicker and will not fit in the slot in the end cover. For some reason I had the thicker cam plate but not the cover with the wider slot. I think that this all came in with last cases from '71 so no machined bit in the gearbox. I found it easier to ease the cases than open up the slot.
Check your cases for the machined flat bit in the gear box. Late '69 bikes were fitted with 1970 engines and the one I have has the machined bit and the strengthened cam plate. I am assuming that the changes came '70/'71.
Dave.
Hi Dave
Not sure what you mean by machined flat and where
Hi,
I have had a look in some cases and the curved bit is quite rough so perhaps not machined. If you look in to the empty gearbox case and on the right, towards the crank case there is either an almost invisible slight indent in the casting or a more obvious rough machined curve. The more obvious curve is to accommodate the reinforcing strap on the selector plate.
Unfortunately I do not have photos of the differences but when I fitted a reinforced type selector plate in my '71 cases the plate would not move when the gear cluster was fitted. I used a Dremel to remove material to give clearance following the almost indiscernible indent in the casting.
Dave.
Just managed to find an image of my cases before I realised they needed modifying. The arrow points to the spot. No photos of after I modified it.
Thanks Dave
I have ordered a casting off eBay 57-4024 supposed to be a 1970 g, box housing so I'll get a camplate to suite