Author Topic: Where to start  (Read 150 times)

Offline Devlin

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Where to start
« on: 13.09. 2019 13:43 »
This may get a bit overlong so I may start with the obvious, I am missing most of the primary drive side including cover' clutch' chain ans sprockets, some things Draganfly have but not clutch parts so to broaden the search and options I have been told some Triumph parts may fit can any one suggest which, the chain I imagine I can have made but anything else I just do not know, also the gearbox will not turn on the kickstart I want to remove it any but whats it attached to its not a unit or pre unit but a hybrid of both again help would be appreciated   
Devlin
Isle of Arran

Offline Swarfcut

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Re: Where to start
« Reply #1 on: 13.09. 2019 16:11 »
 Devlin....The agony office is open, but needs to know a bit more about the bike. If you can give a little more information,  then a few more folks with wide experience of these machines will be able to assist. If it is a standard bike rather than home built special, then when you say "hybrid", do you mean a separate engine and gearbox, but the gearbox bolted to the back of the engine? If so, you have what is known as a plunger, or semi-unit bike.

 The gearbox can be dismantled almost entirely while still in the frame, so sorting the kickstart will be easy, plenty of information on this Forum, BSA Service Sheets, YouTube, Haynes.


Swarfy.

Additional..Reading through your earlier posts, looks like the engine is an A7 Longstroke in a plunger Frame. This engine has two rocker boxes and a pair of cylinder head studs at the back of the barrel, above the magneto. The entire primary drive, with the exception of the crankshaft drive sleeve, is common to all plunger motors until the end of production, so later model A7/A10 Plunger will fit. The drive sleeve varies depending on the year an oilseal was introduced, earlier have a scroll, no seal. With the later oilseal they are smooth, but no seal and smooth sleeve have been reported, so at a pinch any later more common parts should fit. Triumph bits only fit the  later S/A models with a single row primary chain.

Offline Devlin

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Re: Where to start
« Reply #2 on: 13.09. 2019 21:20 »
Cheers for the reply , the kick start seems ok in neutral but in gear its lock but perhaps this is normal , I am a bit away from actually making a start on the renovation but I am gathering as much info as I can ahead of that,
Devlin
Isle of Arran

Online muskrat

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Re: Where to start
« Reply #3 on: 13.09. 2019 21:52 »
G'day Devlin.
When you say "clutch cover" do you mean the outer primary cover or the "saucepan" that covers the clutch?
Do you have a parts book for your model (1950 A7 Star Twin)? Look here to down load the pdf https://www.a7a10.net/forum/index.php?topic=12471.0
We have a dedicated "Long Stroke" section. https://www.a7a10.net/forum/index.php?board=38.0
  As Swarfy said the "semi unit" primary was pretty much unchanged till the end of 56. The c/case oil seal started in 53.
A couple of pics to whet your appetite. (not mine).
Cheers
You beat me in. Yes the k/start will try to turn the rear wheel if it's in gear.
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline Devlin

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Re: Where to start
« Reply #4 on: 14.09. 2019 08:32 »
Thanks the link to the spares PDF is invaluable and it seems I am missing pretty much everything clutch wise as I have only items 24 to 28 on the 49'to 54' model so I imagine they must be with the previous owner so  will ask him to have a look in his garage where the bike has been since the early 70's
Devlin
Isle of Arran

Offline Swarfcut

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Re: Where to start
« Reply #5 on: 14.09. 2019 08:59 »
Devlin.. Musky's fine pictures show a Longstroke engine in all its glory. You can see the timing cover is almost horizontal on the top edge, and the two rocker boxes. Compare this with  Musky's A7, which has the later  so called shortstroke engine. The timing cover is different and the rocker box is a single casting. Although similar engines  there are major differences, and it is important that you identify which engine you have.  The 1949-53 parts book does not cover the earlier Longstroke engine internals, but the parts for the primary drive are the same for both engines except as mentioned above.

 In neutral the kickstart will drive the gearbox mainshaft. With no primary drive, it should move easily. In gear, it will drive the rear wheel as well. Try turning the  wheel, assuming the chain is on. If it is solid, gearbox layshaft and/or main output bearing look to have seized, but don't worry the box is simple to dismantle and bushes and bearings are readily available.

Swarfy.


 Additional..Big thanks to Musky for those three fine pictures, all no doubt taken recently.