Harsh Reality Pics - The Black Museum

Looks very nice indeed. Geez, you were lucky the integral crankpins were still serviceable - with the big end rollers seized with rust the pins must have taken a hit? Or did Red have to replace webs as well?

Out of interest is there any compatibility between the drive side end on that crank and an SF crank. They look very bloody similar. Piet, you'll know!
 
Matthias drove to Breganze yesterday with his beautiful 120 degrees Jota (57,000 km).

He had the carburettors perfectly adjusted / renewed at a local Laverda dealer.

During the test run yesterday on the lifting platform, the middle connecting rod tore somewhere between 4-6,000 rpm and pierced the engine housing to the rear / top.

Shit happens......

The engine will be dismantled by Monday, then we may see what the cause was.

1624696624397.jpeg

Thomas aus LAU
 
looks as though it hasn't done across the joint in the two halves, so not hard to repair the cases, but the gouge doesn't look wide enough for a rod, but it is definetly in the right place for one. if it was at Oro's he most likely has new or used cases or knows where they are nearby, crank and rod parts also, be sure those cases get returned so that you can repair them if that happens. I have a very heavy dummy crank turned from solid with welded on dummy bearings, all solid and cylindrically ground by the MOD, that can be bolted into the two halves prior to welding in order to hold the two halves straight.
CLEM
 
Unfortunately I still have one more current case for the “black museum”.

A friend has built a beautiful black (!) SFC replica. The engine used, was from a friend and ran well until it was stored about 10 years ago. He has a big head and has run about 25,000 km.

In the current "revival", the foot- and head gaskets were renewed, as well as the camshaft chain for safety's sake.
The engine sounded good in the first test runs. After approx. 250 km it became very loud mechanically and the valve clearance was checked.

When the engine got louder, the friend came up to me and asked my opinion.
- the very loud mechanical noise came from the top right of the head
- the right outer camshaft ball bearing was ok.
- the camshaft area was well supplied with fresh oil, the surfaces of the cams looked good (mini camera).
- the valve clearance seemed ok

Only after moving the rocker arm from the inlet did I notice, that the play on both sides was about 1.5 mm (!) larger than measured with the feeler gauge.
The valve stems have a very precise „hole“ at the top, almost like being drilled / milled.

I've seen pitting or slight depressions many times, but never before such a crater. Without a lack of oil, I don't (yet) have an explanation.
Why both inlet valves at the same time?
Why did the previous owner not have any problems with the engine?

Hopefully next week when we dismantle the engine we will come across possible causes.

1624864883648.png

Thomas aus LAU
 
Thomas aus LAU said:
Unfortunately I still have one more current case for the “black museum”.

A friend has built a beautiful black (!) SFC replica. The engine used, was from a friend and ran well until it was stored about 10 years ago. He has a big head and has run about 25,000 km.

In the current "revival", the foot- and head gaskets were renewed, as well as the camshaft chain for safety's sake.
The engine sounded good in the first test runs. After approx. 250 km it became very loud mechanically and the valve clearance was checked.

When the engine got louder, the friend came up to me and asked my opinion.
- the very loud mechanical noise came from the top right of the head
- the right outer camshaft ball bearing was ok.
- the camshaft area was well supplied with fresh oil, the surfaces of the cams looked good (mini camera).
- the valve clearance seemed ok

Only after moving the rocker arm from the inlet did I notice, that the play on both sides was about 1.5 mm (!) larger than measured with the feeler gauge.
The valve stems have a very precise „hole“ at the top, almost like being drilled / milled.

I've seen pitting or slight depressions many times, but never before such a crater. Without a lack of oil, I don't (yet) have an explanation.
Why both inlet valves at the same time?
Why did the previous owner not have any problems with the engine?

Hopefully next week when we dismantle the engine we will come across possible causes.

View attachment 57701

Thomas aus LAU
Click to expand...
Perhaps some valves were used that needed shortening and the hardening was removed. Hard to understand that happening in such a short time.
 
That is not uncommon when aftermarket stainless valves are fitted. Unless they are properly tipped with hardfacing that's what will happen.
"He has a big head" Do you mean big valves ? When were they fitted ?
 
GregT said:
That is not uncommon when aftermarket stainless valves are fitted. Unless they are properly tipped with hardfacing that's what will happen.
"He has a big head" Do you mean big valves ? When were they fitted ?
Click to expand...
Big head in this case:
- SF2-head (factory) with the bigger valves (still factory) for 36 Dellortos

The previos owner does not remember of any change at the shafts (grinding,.....).

Thomas aus LAU
 
I took the tips off my (7mm stem) stainless valves when I fitted the Rotax tappet adjusters, but I'm thinking I'll have to check that enough of the hard face tips are still there. As insurance I'll probably have 1mm added and remove a tad from under the rocker arm. The face of the Rotax items does spread the load across the whole valve tip and pretty much eliminates the digging prob with std tappets, but better safe than sorry - while it's still in pieces.
 
piranha-bro2 said:
I took the tips off my (7mm stem) stainless valves when I fitted the Rotax tappet adjusters, but I'm thinking I'll have to check that enough of the hard face tips are still there. As insurance I'll probably have 1mm added and remove a tad from under the rocker arm. The face of the Rotax items does spread the load across the whole valve tip and pretty much eliminates the digging prob with std tappets, but better safe than sorry - while it's still in pieces.
Click to expand...
What brand are they ? Some are better than others for depth of hardfacing. Valves sold for bucket and shim use will generally have very little depth of hardfacing as they don't need it. Rocker style should have a good layer for safety.
 
A friends SF2 had some inlet valves from Volvo (iirc) fitted, they had been shortened quite a bit. I got him to fit lash caps as I was afraid of the standard tappet adjusters eating into them. The lash caps broke up, they were pretty thin, under 2mm. It has been run without them for quite some time and the valves had stood up last I saw it in autumn last year. I have tipped standard Laverda valves numerous times and they have also been fine. There is clearly no hard facing on the valve in the picture, it could be either a dud or non-genuine. The noise was from the rhs of the head, but are both inlet valves in this state?
 
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