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A10 Crankcases big/small journal crank DIFfrent ? #516978
12/01/13 3:16 pm
12/01/13 3:16 pm
Joined: Oct 2007
Posts: 1,520
Auckland NZ
Ignoramus Online content OP
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Ignoramus  Online Content OP
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Auckland NZ
Catastrophic failure of A10 conrod now means I need to start the process of finding out what I need ....

At this stage all I need to know is if the actual crankcase (timing side) takes a different diameter timing side bush ...im not sure if when they say "small journal crank" it just refers to the big ends? ... something tells me that the small journal crank has a 1 1/4" main bush and the latter ones are 1.5" (like A65) ...but I am not certain

bike is 52 plunger

I know its not really the done thing but has anyone replaced JUST only one side of the crankcase (need to retain the numbers or drama with the licencing dept) ? .. You could tell real fast if it was a no go ,, but only by fitting the crank...

Thanks guys

PS no &^%$%&ing warning just BANG!!!!!!!!!! I suspect sudden oil pump failure as the inside of the motor was bone dry and lots of smoke ,,,,,,,,, summer is just starting here to .......

PSS bike was running like clockwork ........ then........

Last edited by Ignoramus; 12/01/13 3:17 pm.

"There's the way it ought to be and there's the way it is" (Sgt Barnes)
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Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #516979
12/01/13 3:43 pm
12/01/13 3:43 pm
Joined: Sep 2002
Posts: 7,812
Seattle
Alex Online content

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Alex  Online Content

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Seattle
They always run best right before they blow up. grin

I've replaced one side on an A65 crankcase. Shouldn't be much different for the A10. You will have to be sure to align the bores of the crankshaft (should alignbore the new bush anyway) and the camshaft. Also, you will probably have to work the barrel joint face and the sump plate. Otherwise it should be fine. I am fairly certain that fitting a big-journal crank into an plunger motor shouldn't be a problem because yes, the journals themselves are the only difference of consequence.

Sorry to hear you blowed it up...good luck on the reanimation.


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Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #516981
12/01/13 4:01 pm
12/01/13 4:01 pm
Joined: Jul 2006
Posts: 877
newcastle australia
trevinoz Online content
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trevinoz  Online Content
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newcastle australia
Ig,
As Alex says, no problems fitting a large journal crank.
Mixing cases can be a bloody pain. The cam bushes are usually out of line and the decks have to be milled.

Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: trevinoz] #517022
12/01/13 7:05 pm
12/01/13 7:05 pm
Joined: Feb 2003
Posts: 2,884
Ohio
R
Rickman Offline
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Rickman  Offline
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R
Joined: Feb 2003
Posts: 2,884
Ohio
Ig,
Wished we were MUCH closer...

If you wished to keep the original type small journal crank, I've got one I'd trade, but oh well... .010 under, fresh turned too.

Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #517057
12/02/13 1:39 am
12/02/13 1:39 am
Joined: Oct 2007
Posts: 1,520
Auckland NZ
Ignoramus Online content OP
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Ignoramus  Online Content OP
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Auckland NZ
thanks so far guys ......... I don't have A BIG JOURNAL CRANK so if the small journal crank I have is stil useable then I will use that but need to know for sure if the case is different...as in is the bush a different OD in the cases depending on big/small journal crank , are there 2 part numbers for cases ?

Last edited by Ignoramus; 12/02/13 1:41 am.

"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #517093
12/02/13 9:29 am
12/02/13 9:29 am
Joined: Mar 2011
Posts: 833
derby england
wak Offline
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wak  Offline
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derby england
bushes are all the same 1 3/8",iv used loads of odd cases and never had a problem.


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Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #517119
12/02/13 1:59 pm
12/02/13 1:59 pm
Joined: Oct 2007
Posts: 1,520
Auckland NZ
Ignoramus Online content OP
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Ignoramus  Online Content OP
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Auckland NZ
Wak ... so does big/small journal crank only refer to the big end sizes? with the big journal crank having the same main journal size as small journal ? am confused


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #517124
12/02/13 2:43 pm
12/02/13 2:43 pm
Joined: Mar 2011
Posts: 833
derby england
wak Offline
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wak  Offline
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derby england
yes just the big ends


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BSA B50MX
TRIUMPH TR6C
BSA BUSHMAN
BSA Gold Star Daytona
BSA Gold Star Scrambler
BSA Rocket Gold Star
BSA C15S
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Triumph T120
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Triumph T100 Scrambles
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Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #517175
12/02/13 8:31 pm
12/02/13 8:31 pm
Joined: Oct 2007
Posts: 1,520
Auckland NZ
Ignoramus Online content OP
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Ignoramus  Online Content OP
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Auckland NZ
cheers

of course what DOES make the cases different is that its off a plunger bike with the bolt up gearbox mount .... bummer


"There's the way it ought to be and there's the way it is" (Sgt Barnes)
Re: A10 Crankcases big/small journal crank DIFfrent ? [Re: Ignoramus] #517182
12/02/13 9:20 pm
12/02/13 9:20 pm
Joined: Aug 2001
Posts: 3,636
argyll. scotland, uk
gavin eisler Online content
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gavin eisler  Online Content
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argyll. scotland, uk
Its interesting that the 1 inch and 3/8 ths timing side bush size is the same as the OD for a BSA bicycle bottom bracket cup, not a lot of people know that.


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