Looking for 650ss head

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Muffers for a Manxman are I believe unobtainable, however they apper to be as per standard 650SS/ Atlas muffer turned 90 degrees with a mounting bracket welded at the appropriate place. See earlier video on this page.
Thanks Bernhard, that's me in the video ;). Although they look similar, the 1961 Manxman mufflers/silencers are quite different to the Atlas/Dominator (and later 650SS) types that are on Chuck's bike in the video. Cheers, Mike
 
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SHould definitely be a spigot barrel and head. I would take a crack at milling the spigot out if all I could fine is a not spigot head. Would scare the S**t out of me but should work.
A regular automotive machine shop should be able to easily take a tissue paper skim grind for a no stress removal of that nasty spigot on the barrels.

I have a head with 69mm diameter recess and 26.5 diam inlet ( steel stubs set into head)- casting no. is 25319 and has one valve seat missing, and one with same casting no, with 74mm recess and standard 28 inlet tracts. Both are available from here in UK.
The 25319 # is one of 13 molds that make up the head. These were definitely late atlas and "possibly" on later 650 as Norton PN 25358.
The C-C head stud spacing for the holes forward from the spark plugs is 6-7/8"
69mm sounds right for a 650 as a 750 would have been 74mm.
The C-C head stud spacing for the holes forward from the spark plugs is 7-1/8" for all 750 heads
Hopefully it has not been butchered with 1.5" intakes as the 650 was 1.4"

 
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I have a head with 69mm diameter recess and 26.5 diam inlet ( steel stubs set into head)- casting no. is 25319 and has one valve seat missing, and one with same casting no, with 74mm recess and standard 28 inlet tracts. Both are available from here in UK.
Hi Jan,
I have a head with 69mm diameter recess and 26.5 diam inlet ( steel stubs set into head)- casting no. is 25319 and has one valve seat missing, and one with same casting no, with 74mm recess and standard 28 inlet tracts. Both are available from here in UK.
Hey Jan

The 69mm recess ought to be suitable if it has the 6 7/8 spacing on the studs forward of the sparkplugs as per dynodave. I have a late atlas head that has the 74mm chamber and 28.5mm tracts that I believe is correct for a late atlas. I am not that experienced with the older dominator stuff but would guess that the steel stub is for a 500??? . Could the steel stub be removed to return it to the 28.5mm that is the same as the atlas I think. If that would work I would be interested. Could you please post a photo?

Thanks i advance. I will revert to the other commando site and do further research as per dynodave.

best, michael
 
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A regular automotive machine shop should be able to easily take a tissue paper skim grind for a no stress removal of that nasty spigot on the barrels.



The 25319 # is one of 13 molds that make up the head. These were definitely late atlas and "possibly" on later 650 as Norton PN 25358.
The C-C head stud spacing for the holes forward from the spark plugs is 6-7/8"
69mm sounds right for a 650 as a 750 would have been 74mm.
The C-C head stud spacing for the holes forward from the spark plugs is 7-1/8" for all 750 heads
Hopefully it has not been butchered with 1.5" intakes as the 650 was 1.4"

 
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THanks dave, i would think that would work as well. Do you have any idea why this was done in the first place. Just curious. M
 
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THanks dave, i would think that would work as well. Do you have any idea why this was done in the first place. Just curious. M
Well since this old equipment was designed (1950) while I was still in diapers, I'll admit I have no idea... LOL
Maybe the brits have heard the "stories" and can pass it on to us.
By the time of my first bike, a brand new 70 comando roadster, the spigots were long gone.
I know for boreing and sleeving they are a pain in the butt. I'd much rather shrink fit a squish band ring in an early head than try and re-establish a cylinder spigot.
Learning this early pre Berliner norton stuff is a bit difficult in north america. Especially as I have found out the readily available info is often inaccurate or embelished .
Rumor is the early 650 had the port inserts also. A stock 650 with the SS/22729 cam was, IMO, like a combat commando or relatively even hotter....
The 28.5mm port head when installed on a stock combat commando makes more power than a HC 32mm (sloppy) port head. I still have the dyno sheet print out here somewhere.
 
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Hi Jan,

Hey Jan

The 69mm recess ought to be suitable if it has the 6 7/8 spacing on the studs forward of the sparkplugs as per dynodave. I have a late atlas head that has the 74mm chamber and 28.5mm tracts that I believe is correct for a late atlas. I am not that experienced with the older dominator stuff but would guess that the steel stub is for a 500??? . Could the steel stub be removed to return it to the 28.5mm that is the same as the atlas I think. If that would work I would be interested. Could you please post a photo?

Thanks i advance. I will revert to the other commando site and do further research as per dynodave.

best, michael
Hi Michael, I can’t post pics directly, but will send some I have just taken via direct email: mine is jannelder ‘at’ aol.com. It has 6 7/8 spacing and steel stubs are 28.5 and should be removable. They go right in to the valve guides. No broken fins, and exhaust port threads good.
 
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Thanks, Jan. I am thinking that that head may work fine but cannot visualize the steel stubs so the picture will be a big help. I will send you an e-mail from my private mail mkm "at" bskb.com tomorrow. Thanks for the help. Michael
 

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