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A7 & A10 Engine
A7 1946-1950
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A7 & A10 Engine
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A7 Head onto A10
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Topic: A7 Head onto A10 (Read 1183 times)
A10 JWO
Resident Legend
Join Date: Oct 2012
Posts: 730
Karma: 2
A7 Head onto A10
«
on:
16.04. 2013 16:26 »
Hi Chaps.
Will the alloy A7SS head fit the early swinging arm A10 that was fitted with thick flange barrels. If so are there any main issues, valve sizes etc.
Many thanks Colin
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metalflake11
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Join Date: Aug 2012
Posts: 678
Karma: 9
Re: A7 Head onto A10
«
Reply #1 on:
16.04. 2013 16:42 »
Ran mine for years like that. I had a 389 monoblock with standard A10 jetting.
Very economical, good plug colour, good starting and no difference in power, other than on very big throttle openings.
mf
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England N.W
1960 A10
England
A10 JWO
Resident Legend
Join Date: Oct 2012
Posts: 730
Karma: 2
Re: A7 Head onto A10
«
Reply #2 on:
16.04. 2013 17:03 »
Thanks for that, I will go in search in my mates shed. Are the exhaust ports in the same place and size.
Colin.
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Duncan R
Valued Contributor
Join Date: Sep 2008
Posts: 291
Karma: 3
Re: A7 Head onto A10
«
Reply #3 on:
16.04. 2013 17:31 »
Hi ,
Mine runs that set up as well but with a concentric carb, bike was originally a 500 but gained 650 barrels at some point. Can't say I have had any problems but then again I have never ridden a "proper" 650 so nothing to compare but it seems to perform quite well.
I bought some s/h down pipes from a Super Rocket from E Bay and they went on with no problems so I guess ports must be the same size.
Cheers
Duncan
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Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS
metalflake11
Resident Legend
Join Date: Aug 2012
Posts: 678
Karma: 9
Re: A7 Head onto A10
«
Reply #4 on:
16.04. 2013 17:44 »
All the same, just smaller valves and inlet port.
If memory serves me well, the head that's on now, used to be an A7SS and was later converted to A10 spec by SRM.
mf
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England N.W
1960 A10
England
muskrat
Global Moderator
Wise & Enlightened
Join Date: Jul 2009
Posts: 10787
Karma: 130
Lithgow NSW Oz
Re: A7 Head onto A10
«
Reply #5 on:
16.04. 2013 20:59 »
Yep, same, same. But if using high top pistons the rim of the combustion chamber will need to be blended to the larger A10 bore. A10 valves (1.38"ex & 1.41"in) can be fitted with a little work on the seats.
Cheers
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'51 A7 plunger, '57 A7SS racer now a A10CR, '78 XT500, '83 CB1100F, 88 HD FXST, 2000 CBR929RR ex Honda Australia Superbike .
Australia
Muskys Plunger A7
bikerboy
Valued Contributor
Join Date: Dec 2011
Posts: 447
Karma: 4
Re: A7 Head onto A10
«
Reply #6 on:
17.04. 2013 02:12 »
The first time i did this I fitted the bigger valves but being young had no idea how to machine the head so I used two solid copper head gaskets. It ran absolutely fine and I used it for at least 3 or 4 years
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WozzA
Wise & Enlightened
Join Date: Nov 2011
Posts: 1480
Karma: 18
Melbourne Australia
Re: A7 Head onto A10
«
Reply #7 on:
18.04. 2013 15:11 »
I just used a dremel to clean up & increase the chamber to 70mm
& fitted the bigger valves.
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'51 Golden Flash Plunger
'57 Golden Flash Swingarm
Melbourne
The biggest lie I tell myself is
"I don't need to write that down, I'll remember it"
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The BSA A7-A10 Forum
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Technical (Descriptive Topic Titles - Stay on Topic)
»
A7 & A10 Engine
»
A7 Head onto A10