XS1 Cylinder Head Valve Seats

[Bewarethemoon]

Can anybody point me in the direction of the information relating to the above, in particular that the XS1 valve seats aren’t hardened?

I know I’ve read about it on here but can’t for the life of me find it again.

Daniel.

 

[TwoManyXS1Bs]

Try these 2...

http://www.xs650.com/threads/xs650-and-leaded-fuel.47163/

http://www.xs650.com/threads/fuel.50315/

 

[Bewarethemoon]

Thanks again Two Many!
I’ve just found the top link again actually, I’m trying to decipher if I need to have something called a “lead free conversion” carried out on my valve seats before I have them recut by the machine shop I’m using.

 

[TwoManyXS1Bs]

The seats are actually a part of the entire combustion chamber "shell", not separate and replaceable. Have you seen the "head cutaway" pics?

http://www.xs650.com/threads/cylinder-head-cutaway.30559/

 

[Bewarethemoon]

The seats are actually a part of the entire combustion chamber "shell", not separate and replaceable. Have you seen the "head cutaway" pics?

http://www.xs650.com/threads/cylinder-head-cutaway.30559/

I can see how they couldn’t be replaced.

So my takeaway from this is that the valves were changed but I’ve seen nothing conclusive to say the valve seat area’s not hardened?

Wouldn’t we of heard of many problems if people were having valve jobs done to early heads not knowing this? It seems quite an obscure little piece of trivia so not commonly discussed.

Daniel.

 

[TwoManyXS1Bs]

Yeah, this issue doesn't show up here like it did on old auto cast-iron heads...

 

[Bewarethemoon]

Yeah, this issue doesn't show up here like it did on old auto cast-iron heads...

So I’m ‘probably’ okay to have my seats recut?

Another interesting little bit of trivia, I’ve heard from a reputable source that some of the early heads didn’t have identification numbers stamped into the casings, I have two XS1 heads and they both have numbers stamped in which leads me to believe Yamaha began stamping the numbers later into the production run

Daniel. .

 

[TwoManyXS1Bs]

Sure, just keep the cutting to the minimum, just enuff to clean them up. You going to use the later valves?

No ID stamps? That's *another* to add to the mysteries of the early bikes...

 

[Bewarethemoon]

Sure, just keep the cutting to the minimum, just enuff to clean them up. You going to use the later valves?

No ID stamps? That's *another* to add to the mysteries of the early bikes...

I’m going to have a 5 angle cut, I’m using a set of oversized valves from Smedspeed.

There’s also a slight difference to the top cover apart from the 4 3 holed valve covers, the area between the oil feed pipe banjo fittings is a semi-circled d shape, whereas it’s a flat rectangular shape on the later heads.

 

[Beags64]

'71 motor believe to be original - Ser.# S650-007406 - all 3 hole covers, square between covers, does have matching numbers on head and cover. Not sure if this helps figure time line or not

 

[Bewarethemoon]

'71 motor believe to be original - Ser.# S650-007406 - all 3 hole covers, square between covers, does have matching numbers on head and cover. Not sure if this helps figure time line or not

Square between the oil feed inlets?

 

[Beags64]

Top of the cover between banjo bolts? Yes...

 

[Bewarethemoon]

Top of the cover between banjo bolts? Yes...
View attachment 186824 View attachment 186825

Top of the cover between banjo bolts? Yes...
View attachment 186824 View attachment 186825

Although both heads featured in this photo are of the later 3 3 hole 1 4 hole variety it illustrates my point about the difference in castings above the cam sprocket.

Interesting there were differences in the castings of the heads in such a limited production run no?

Daniel.

 

[Jim]

Well sumbich.....
XS-1B

 

[Bewarethemoon]

Well sumbich.....
XS-1B


View attachment 186854

View attachment 186855

Very curious isn’t it Jim?

 

[Jim]

It is....

 

[Bewarethemoon]

It is....

What were they up too?

Seems wasteful to have different castings within such a short period, makes me wonder about the ports.

Daniel.

 

[Jim]

What were they up too?

That's the tunnel the cam gear and chain runs in. Looks like it was originally cast half round.... just because they could.
The square (rectangle) casting is ground off on the top. So I suspect that's (one of the places) where the molten aluminum was poured... then they ground off the excess. Maybe it was just easier to do that way? Or..... Could be they started casting multiple units in "trees" and that's where the "branch" was.
"Course, that's all just a guess on my part.

 

[Mailman]

Huh.....my XS2 also has the round casting for the cam chain tunnel.

 

[Bewarethemoon]

I spoke to the machine shop I’m sending my cylinder head off to for valve seat cutting, diamond honing of valve guides & surfacing.

We briefly chatted about ‘lead-free conversion’. He wasn’t particularly informed about it’s necessity in regards to an early XS head but had come across it many times in the classic car world.

He said typically you need a minimum of 10mm of material to cut out to install new seat material, something he didn’t think an XS would provide, I had to agree, especially considering the head cutaway images TwoMany provided

He said that the classic car guys are very reluctant to have this service done as there are reliability issues, the new seat can come free of the combustion chamber.

He recommended lead additive in fuel. This was confounded doubly for me by the added bonus of lubricating drive train.

Good news hearing I don’t have to embark on an additional costly endeavour that could eventually turn out to be fruitless (read catastrophic).

Daniel.