The fall and rise of a works SFC engine

Hell of a sight, I will long remember the detailed chat we had at The Barry about your mystery barn find. It will rise again I am sure.
 
After the initial dismay and disappointment, I now see it as an engineering challenge, not going to let the fucker get me down! :D
As the cases are unique, there is a special incentive to get it back on track, and not only as a static display piece.  Rods and pistons are sorted, barrel repaired.  Quite glad the very special gearbox was unharmed. 

Bit of a shame I've let it idle for so long, but life tends to get in the way.  After all, it's just a toy.  Cannot yet say when it'll be finished, but I hope to do the Bikers Classics in 2022 with it.  There is also a rumour of a rather special event in 2021... gotta set yourself a perspective.  After that, see what happens.

This is actually the first Laverda engine I've managed to trash, my others were just generally worn out.  This one sure went out with a bang! :D

piet
 
sfcpiet said:
Reckon it's a bit moot to speculate over what let go first, rod or piston.
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Piston didn't actually let go. it's still hanging onto the gudgeon pin by the skin of its teeth. Doesn't look like it seized either, so my bet is the rod snapped first.
 
chrisk said:
:o What a mess. You have a hell of a job ahead of you.

Did you pick up all the bits to put Humpty back together again?
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Na, most of it went out the front of the fairing, littered around the chicane exit of Paul Ricard/le Castellet.

Cam, piston is cracked in several planes on both sides.  If it let go on one side, the rod would quickly get a bit crook.  Everything between big and small ends is missing.

piet
 
Hmmm, chicken or the egg? Which one is the horse, which the cart? Either way, big job ahead, Piet, but if anyone can get it done, you can. I have every confidence. In a way it's a bummer that the cases are so special, because it means repair is your only option. I notice that the rods don't have the castellated oil reliefs that my later SFC rods have. No shortage of oil anywhere though!
 
Now don't take this the wrong way as there is a bit of Irony involved and I know how much you like them, would a section of Zane case work. They might be easier to find broken. Are they all sand-cast, the grain on the broken cases looks gritty, same alloy used on all Laverda engine cases over the years?
 
No shortage of buggered Zane cases Vince.  But there is absolutely nothing on them that will even vaguely fit.  I've already found a stock 750 crankcase that will donate the missing bits, it's actually a quite close match with only minor details requiring mods.

I'm actually cutting up a lower 668 case to rescue a knackered OR600 case that somehow lost one of its lower rear fixing points...

piet
 
Nothing is unfixable, it just depends on the afford and cash you throw at it. Not sure though which is the bigger one of the two...  ::)

But my confidence in you are the highest, Piet, as you know. If someone can manage it, it will be you! Go for it, don't let that piece of history go down. Cross my fingers it turns out very nicely!!
 
Guess gasket surfaces (e.g. cylinder base) could be challenging to refurbish after the welding is done. How will you approach this
(I know you are good with a straightedge and an arkansas stone)?
8)

In what details such an SFC case differs from a std. one ? always thought just the innards would be unique ..?
???
 
Jo said:
Guess gasket surfaces (e.g. cylinder base) could be challenging to refurbish after the welding is done. How will you approach this
(I know you are good with a straightedge and an arkansas stone)?
8)

In what details such an SFC case differs from a std. one ? always thought just the innards would be unique ..?
???
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Generally, yes.  1973, no. 

And that's a BIG no! :D  Happy to show you the differences next time you drop in.

piet
 
Sorry for that! A good Welder can do the Job.
"Works-Engine" means a Racing Engine? Looks like somebody has Ignore the "Works-Instructions" of Fixing up the Engine....  The Duration on a 45 Yrs old Engine on Racing is not forver.... Espacially when there ist not enougt Oilpressure like on that, as you can see at the Blue Crank.....
Anyway, I got the verry same on a Honda RC45....
:(
 
Youve blown an RC45?😮 Wouldnt have thought that possible for mere mortals😉 so commiserations or congratulations depending how you look at it! Horrendously pricey to fix  presumably?
 
Thought there isn't any oil pressure at all, as the conrod bearing got its oil supply by the crank slingers as usual? I'd guess the blue traces come from induction hardening of the crank pin bore.

Nice mess you got there, Piet, holy s..t :o Conrod failure as primary damage source would require fatigue damage to initiate. Some traces of initial fatigue crack might still be visible at the fractured surfaces, depending on how badly smashed they are. If you could keep the bits of the conrod, I'd like to take a look at them at my next visit in the west, which I have already on my books anyway.

Regards,
Stefan
 
hochkoenig said:
Sorry for that! A good Welder can do the Job.
"Works-Engine" means a Racing Engine? Looks like somebody has Ignore the "Works-Instructions" of Fixing up the Engine....  The Duration on a 45 Yrs old Engine on Racing is not forver.... Espacially when there ist not enougt Oilpressure like on that, as you can see at the Blue Crank.....
Anyway, I got the verry same on a Honda RC45....
:(
Click to expand...

Works means works racing engine. Works as in factory.

Look at the crank and rods.
And you haven't seen the head.

Paul
 
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