Cylinder head marking

[LOS56]

Hi, I have a question about cylinder head marking. I know that a Corsa head normally have a “CR” marking which I also have on my Corsa. However, I have a Mirage which is said by previous owner to have Corsa head, it’s marked with “C” only. I haven’t had the head off so I don’t know. Anyone know what the “C” stands for?

Regards Lars

Attached pictures of cyl head from my Mirage and my Corsa

 

[Laverdalothar]

Hi Lars, can be actually anything from a factory stamping where they forgot to stamp the R to self made after a revision/rework of the head to a fake.

Are the Inlet channels 36mm? If so, there is a chance it is a Corsa-Spec head (factory or reworked). If they are still 32mm, almost certain it is a fake.

Carbs are easy to take off or if you have an endoscope camera, you can even leave them on the bike, lift the sliders and go down the inlet. 1st indication would be a step between head and inlet if the Carbs are 32mm and manifolds are not tappered.

Second indicator: on standard heads, the valve seat ring protrudes into the inlet channel and has a noticable step, too. On 41mm inlet valves, the rings are larger and "hide" in the casting of the inlet channel.

HTH

 

[CLEMTOG]

"Corsa" heads fitted to late SFC1000's were not stamped by the factory at all. That "C" looks too big and wrong to me, so as Lothar suggests, but in more detail, off with the carbs, out with the vernier, and measure the inlet port throat size, this can still be a non factory modification, but unless you take the head off, you won be able to measure the valve sizes.
CLEM

 

[Laverdalothar]

"Corsa" heads fitted to late SFC1000's were not stamped by the factory at all. That "C" looks too big and wrong to me, so as Lothar suggests, but in more detail, off with the carbs, out with the vernier, and measure the inlet port throat size, this can still be a non factory modification, but unless you take the head off, you won be able to measure the valve sizes.
CLEM

Clem, you actually can identify it indirectly as described above. If the inlet valve seat ring is protruding into the inlet channel, there is a very fair chance it is a small valve head. To be 100% sure though - I agree - you need to take it off and measure it properly. Still, ANY head can be altered to Corsa specs. That is basically how they built them - use larger valves and bore out the inlet to 36mm.

 

[sfcpiet]

"Corsa" heads fitted to late SFC1000's were not stamped by the factory at all. That "C" looks too big and wrong to me, so as Lothar suggests, but in more detail, off with the carbs, out with the vernier, and measure the inlet port throat size, this can still be a non factory modification, but unless you take the head off, you won be able to measure the valve sizes.
CLEM

To my knowledge Clem, all SFC1000 heads were thus marked, at least those that originally came to Germany. Many of these bikes passed over my workbench, all carried the "CR" stamp. Some engines were also stamped at the rear lower LH mounting lug. The RGS Corsa was never officially offered here due to trademark disputes with GM/Opel.

One of the first actions when one of these rolled into the yard was to verify the CR stamping in order to know exactly what we were looking at.

Not proclaiming there aren't any fakes out there...

piet

 

[CLEMTOG]

I have had several SFC1000's here Piet, bought on behalf of pals, they were all one owner from new bikes, with verifiable untouched engines, and the lack of "CR" mark allways made me suspicious one of them is with Per Erik in Alta who you visited recently and another with Preben Ingermason (probably spelt wrong sorry Preben) in Denmark, interestingly the ex Paul Mullholland Corsa (i also sold that) is still in the UK with... damnit cant recal his name , he is 4 km from Coxy. also has no CR and that is a Corsa, currently in bits, deffo a "CR" head but not stamped. My own Corsa was stamped "CR" and is only 4 numbers away from the one in bits, sold that as well (Owen Smith did a superb rebuild) Years ago as in decades, Henry Morgan UK, damaged the head on his Jota and bought a new casting from Slaters, it was a Corsa head, existing valves did not fit and that also was a "CR" head with no stamp, Slater said at the time that this was the only head Moto Laverda were selling, (or was the cunning old git aiming at selling six valves?) the earlier head was said to be being NLA. that Jota is now in Aus, unless that changed in the last 25 year
CLEM
come forward if you have a late SFC1000 without the stamp, and for that matter a Corsa.

 

[CLEMTOG]

A bit like 3CE's, they should have "3CE" stamped diagonally mid way in the chassis number, but do they all?????
CLEM

 

[Preben]

As Clem already mentioned I have an SFC (3424) without the CR stamping on the cylinderhead. Aquired with great help and support from Clem in 2007 (happy days Clem) It was sold new from Windy Corner in UK in december 1988.
Right now my SFC is completly apart due to a cosmetic restauration. So I have just taken a few photos of the cylinderhead and the stampning on the crankcase. The cylinderhead has the right 36 mm inlet ports. It has the right valves 40,5 intet and 34 mm outlet. Stamping on the underside of the head shows it was made in june 1988. So no doubt a genuine SFC cylinderhead. As already mentioned there is a few other late SFC’s without the CR stamping and other SFC’s with the CR stamping. Perhaps due to the conditions in the Factory during the production of the last SFC 1000
Regards
Preben