650ss spigot head modifications

Ubable to find a good 650 spigot barrel, I'm thinking of installing rings in one of my spigot heads, to use with my late non-spigot 650 barrel. I've heard .020" overbore is the maximum size for running these rings.

Atlas head spigot rings are available from RGM but I've been unable to such find rings for a 650.

Has anyone installed or made alloy spigot rings and is it prefereable to tack weld them in the head so they don't dislodge?

Good early spigot heads seem to outnumber the availability of spigot barrels.

Is there any advantage to the spigot cylinders, which makes them preferable with a 650 head?

Here's a some thoughts on your discussion above - I have a 1964 650ss with spigotted barrel/head.

I don't think the spigot offers any real practical advantage and is probably a hangover from when bikes did not have cylinder head gaskets and the singles used to have their spigotted iron heads lapped onto the barrel with grinding paste.

That said, if your head is made to accept a spigot, you could always have an old barrel sleeved back to original size (68.000mm?) and as part of that have the spigot incorporated? I believe that some value of modern sleeves is the better metallurgy of the sleeves compared to that of the barrel - rings seal better and last longer.
My spigots' OD are 72.4mm and stand 3.7mm above "deck"
My barrel is on 2nd oversize - the spigot is 1.7mm "thick" so originally would have been 2.2mm.

Cheers

Edit: Does the piston top protrude from the barrel at TDC? It does on the 500 single. If so, maybe that's a reason not to have a "step" (eg: ring) at that critical point?

Sleeving is an expensive proposition.. The sleeves are expensive and so is the labor.
If anyone has a 650 sleeved barrel I can buy, I'd be interested.
Alternatively, I can weld up the cylinder head. I'm still looking for the 650 head spigot rings and a part number.

elefantrider said:

Sleeving is an expensive proposition.. The sleeves are expensive and so is the labor.
If anyone has a 650 sleeved barrel I can buy, I'd be interested.
Alternatively, I can weld up the cylinder head. I'm still looking for the 650 head spigot rings and a part number.

Click to expand...

Check with Jim Schmidt of JS Motorsports (jseng on this Forum). I think he has worked with spigot rings.

RGM has 650 spigot liners. Not a bad price. Anyone have experience with them?


If I'm going through the trouble and expense, would prefer a Nikasil liner, if available. But I need to find a good donor 650 barrel first.

I have a spare 600 barrel but it looks strange beneath a 650 head.

elefantrider said:

RGM has 650 spigot liners. Not a bad price. Anyone have experience with them?

SPUN CAST TWIN CYLINDER LINER WITH SPIGOT, 600, 650

PLEASE CLICK THE LINK BELOW FOR DIMENSIONS AND MORE INFO ON CYLINDER LINERShttps://s3-eu-west-1.amazonaws.com/rgmnorton/fs/pdf/cylinder_liner_drawing.pdf FOR

www.rgmnorton.co.uk

If I'm going through the trouble and expense, would prefer a Nikasil liner, if available. But I need to find a good donor 650 barrel first.

I have a spare 600 barrel but it looks strange beneath a 650 head.

Click to expand...

Yep - they're few and far between alright!

Liners look good - though at 71,5mm OD that's only 1.75mm thick for a standard bore!
That'd be pretty thin if you start oversizing later.
Cheers

Std bore pistons are 68mm. Somewhere I believe I saw it wasn't recommended to go past .020 overbore (68.5mm) on spigot cylinders but maybe that was for when running the rings in the spigot head so they don't fall out!

If you have a good, but worn, barrel pair, you might consider nickel plating the bores, rather than sleeving. Nickel plating can restore a bore to standard size, or whatever overbore you choose.
Nickel plated bores are million mile candidates.

For example (not an endorsement) see ....


Slick

Looks expensive and maximum recommended build up thickness is only .003-4".
In any case, I need to find a 650 spigot barrel first.

elefantrider said:

Looks expensive and maximum recommended build up thickness is only .003-4".
In any case, I need to find a 650 spigot barrel first.

Click to expand...

I took a closer look at their website. They claim they can bring back a bore 0.020". Their's is a nickel silicon process. I remember a vendor stating they could do electroless nickel as thick as you could pay for. No matter which process, it has to be less expensive than a sleeve, which can be risky from a heat transfer ( overheating standpoint).

Nickel plating is the way I plan to go if i am still living when the bores in my Atlas need refreshing.

Slick

texasSlick said:

Nickel plating is the way I plan to go if i am still living when the bores in my Atlas need refreshing.

Click to expand...

I think you will find that Millennium Tech services non-lined alloy barrels only.

- Knut

elefantrider said:

RGM has 650 spigot liners. Not a bad price. Anyone have

Click to expand...

elefantrider said:

RGM has 650 spigot liners. Not a bad price. Anyone have experience with them?

SPUN CAST TWIN CYLINDER LINER WITH SPIGOT, 600, 650

PLEASE CLICK THE LINK BELOW FOR DIMENSIONS AND MORE INFO ON CYLINDER LINERShttps://s3-eu-west-1.amazonaws.com/rgmnorton/fs/pdf/cylinder_liner_drawing.pdf FOR

www.rgmnorton.co.uk

If I'm going through the trouble and expense, would prefer a Nikasil liner, if available. But I need to find a good donor 650 barrel first.

I have a spare 600 barrel but it looks strange beneath a 650 head.

Click to expand...

Yep, I had these liners fitted to my badly scored 650 Standard barrel. That was c. 1996 tho!! No problems with them since...

For non-spigot applications, I'm guessing you would machine flat the spigot? Looks like RGM only sells liners with spigots.