Laverda non start new

hello Pierre, I would say too much fuel is getting in causing an unusually high compression pressure, so check the float valve tips and then the float heights, if that does not solve it, connect a car battery direct to earth (-) and then touch the plus (+) lead direct on to the brass terminal of the starter motor, if it turns normally then you have a wiringing or relay problem, if that fails get Marilyn to tow you everywhere on her 500!!!
CLEM
 
Here we are:
Bendix spring retainer properly located.
Every part had been properly lubricated before starting the engine.
Pistons found faulty although clearances are as recommended for rings as well as skirts.
I will be getting rid of the pistons (Ross made) and revert to Omega or original Mondials.
Will be keeping you posted.
Thank you very much for your kind advices
 
Peter77 said:
Every part had been properly lubricated before starting the engine.
Pistons found faulty although clearances are as recommended for rings as well as skirts.
I will be getting rid of the pistons (Ross made)

Thank you very much for your kind advice
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Pierre, thank you for your updates we all learn from others experiences when you share. Did you check the cam timing? What was wrong with the Rossi pistons were they new, did you get a rebore ?  The more information you provide the better the experts on this site are able to help you
 
Cam timing is fine and the engine is not overfed with petrol.
It happens that the Ross pistons were made with the piston deck to high.
1200 pistons' deck is lower than 1000s. The pistons have been rectified (height and domes), skirts clearance 0.08 mm looked fine, evrything was well lubricated when reassembling and the the engine was rotated by hand without the plugs to prime the oil circuit.
Engine would then stop dead under compression with the plugs fitted whereas it ran, although not freely as could be expected, plugs removed or by hand.
Thinking about a weak starter, I opted for starting using rollers which may not be the wisest decision I have made.
 
You need minimum (and ideally) 1.0mm clearance at squish band (deck height it seems you call it) and to the valves at overlap. Under that the pistons will contact at high revs. Have you actually measured what your compression ratio is?
 
Paul Marx said:
I think that by deck height, we're talking about height from edge of piston to gudgeon pin?
Paul
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Normally referred to as compression height or pin height.  Deck height would be the difference between piston edge at TDC and cylinder gasket surface.

1200 pistons are shorter than 1000 pistons by the height of the liner spigot, which the 1200 doesn't have.

piet
 
There was some dodgy pistons from Ross supplied by Wolfgang that I not sure what happened but the end result was really high compression like 12 0r 13 to 1.
Red could tell you all about it. I had a set of these pistons which I fitted when rebuilding my 1200 engine. It was all zipped up when I got an email from Red asking me about what pistons I used and was then told to replace them as the compression was way too high. Maybe it was Red or Crispen that had trouble with blown head gaskets and the cause turned out to be the pistons being really high compression.
I talked to Wolfgang about it and he said that there was a problem with them and he was about to have a legal issue with Ross who were saying they were made to his specs which he disputed saying they fucked up. I had these pistons on my shelf for a few years before fitting them after spending $150 on them for ceramic coatings etc. Red ended up supplying me with a set of his Ross piston that were made to his spec and what a work of art they were too and about 100 grams lighter too. Never found out the final outcome between Ross and Wolfgang were but as Red sort me out I didn't follow it up. I believe Red took a big hit having to rectify several engines that he'd fitted the dodgy pistons in.
Could be why your engine wasn't turning over.
 
Red gave me one of the 'wrong' pistons he got from Ross a few years back, when he built an engine for me. He told me it was only good for use as an ash tray, but I don't smoke. It's still sitting on my mantlepiece as an ornament. It's a lovely looking piston with beautiful casting and machining, and with Teflon coated sides. It's a shame they cocked-up the CR. I suppose you could use them with a ?" head gasket!
 
Yes, Red has a tale or three about errant Ross orders and has taken the hit more than once. Had Ross make me 4 pistons using Wolfgang's (correct)  specs from a 74 SFC, but extending the flat swish to give a similar CR but out to 89mm. Tippie has the other pair, mine went into an 'emergency' build for an SF(C) racer for the Barry a few years back - ran sweet and I believe they're still running sweet. Red then had new 87 or 88mm ones made to higher spec shape, but it took a few goes. They are very high quality slugs. Unless there was a design issue I wouldn't be tossing them.
 
It seems that my practice of always measuring clearances and combustion chamber volume is worth the relatively minimal effort. Take nothing for granted.
 
Peter77 said:
Well, I'm afraid that the Teflon from the coated sides went when the pistons were re-machined and thouroughly cleaned. Hence the seizure.
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Remachined? What for? Sounds a bit odd. I prefer non-coated piston skirts  ... just my personal choice.
 
helicopterjim said:
Yeah ....... I've tried to get through that teflon shield a few times ...... with no luck. Afterwards I think that it was probably a good thing.

Jim
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Better than chewing your arm off to get out of there in the morning.
??? I must be getting old, once I wouldn't have cared.
 
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