A7 Head onto A10

[A10 JWO]

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

[metalflake11]

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

[A10 JWO]

Thanks for that, I will go in search in my mates shed. Are the exhaust ports in the same place and size.
Colin.

[Duncan R]

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

[metalflake11]

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

[muskrat]

 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

[bikerboy]

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

[WozzA]

I just used a dremel to clean up & increase the chamber to 70mm
& fitted the bigger valves.