Anyone recognise these SF750 pistons??

[AndyB]

Always nice to see where things are made...

 

[lavfancier]

Hello all,
I have a set of forged pistons to go into a 750 motor bought off ' the bay' a few years back. Not sure what the CR is but looks to be >10:1. I'll check this out when I can.

If you can calculate the CR by simply looking at the piston you have a rare talent! 

Rare talent indeed!!-I had estimated the CR by comparing profiles to the photos in my now very well thumbed Green book to the pistons I have around me.
I'll add a few more details shortly but I think my original thought on the pistons being 1200 items was incorrect as the deck height appears to be correct maybe GT or GTL items?
LF

 

[lavfancier]

Clem,

Even if you get 1200 pistons installed correctly in a twin, the valves clout the piston crown... it's the wider included valve angle.

I fitted flat-top 1200 slugs with my long-stroke crank, first trial run gave a nasty rattle.  Turning through by hand showed all was OK, didn't think I'd need to measure valve/piston clearance, stupid me!  Machined the valve pockets a little and everything slotted together just fine.  Done 50000km with that engine, wonder what it's like inside ???

BTW, deck height for stock 750 is 34.5mm (pin center to crown base), 1200 is 3mm less, ie, 31.5mm.  Late SFC will be similar to 1200.

Just got these in today, 82mm Assos.  Exactly the same as yours, Fancier!   Guess we can consider the mystery as being solved.

piet

Thanks Piet- ASSO?s it is then.

Here?s a summary of the masses:
Asso forged piston 10:10?  Total mass including rings/pin and clips =432.5g Pin alone =65.3g
Mondial SF Piston    9.65:1? Total mass including rings/pin and clips =434.46 Pin alone =92.62g
Mystery Piston        8:10?    Total mass including rings/pin and clips =426.88 Pin alone =92.62g

LF

 

[sfcpiet]

It works ok in Italy proper since they know that only some rules have to be followed some of the time, but in Tirol, being essentially german, they follow everything to the letter and almost everything is impossible.  Not sure how accurate it was, but I found it amusing.

Actually very acurate, that's essentially what it boils down to, Steve.

Asso Werke are located in the Pisa region.

Strange, "Werke" (works) is definitely a german term.... which italian actually works?

piet  (bolt)

 

[Gerald]

I recall reading somewhere (bike mag?) that Asso was a company once owned/founded by Mahle in Germany.
That would explain Asso Werke.

HTH
Gerald