This bloody bike. 1976 3CE

To be honest you may have been better served to get rid of it and take the hit.
Funnily enough those old 3C's still run well when they are clapped out, mine did anyway.
I swopped the engine for a 10,000 mile one from a crashed bike because it was cheaper than a rebuild and the replacement motor was a total slug in comparison.
 
pf1 said:
To be honest you may have been better served to get rid of it and take the hit.
Funnily enough those old 3C's still run well when they are clapped out, mine did anyway.
I swopped the engine for a 10,000 mile one from a crashed bike because it was cheaper than a rebuild and the replacement motor was a total slug in comparison.
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That could have been simple stuff like cam timing and general quality of tune. If everything is right then the motor should run just fine.
 
I bought forged Ross pistons for my 750 from Wolfgang that came with Ross rings so there must be a reason yours are from Japan since yours is a triple. Wolfgang says Ross is good quality and best of luck on your rebuild and keep us posted.
 
So took Wolfgangs parts over to my engineer and had the chance to look at the pistons and bores. Plenty of scoring and erosion in the bores and valve seats. Engine just sat and corroded?

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I've seen way worse, pistons don't look too bad, don't see much blow by, what I do see is a very sooty combustion chamber and piston tops, obviously very rich and or weak ignition system , hope your engineer knows his way around a Laverda cylinder head, good luck with your project
 
#21327 ? Previous job number? Mileage at last head off? Most Laverdas have “sat” for a while at one point in the last 45 years- mine sat in Mums shed for 30 years but I did have the foresight to oil the top end and bores when I was 19 thinking it might be a while till I get round to it…52 when I finally fired him up! If this is the yellow one, then I went to Bideford following it & it went really well in 2022. Trouble is once you start , you keep finding 50 year old problems. You’ll get there.
 
Exmoor beast said:
#21327 ? Previous job number? Mileage at last head off? Most Laverdas have “sat” for a while at one point in the last 45 years- mine sat in Mums shed for 30 years but I did have the foresight to oil the top end and bores when I was 19 thinking it might be a while till I get round to it…52 when I finally fired him up! If this is the yellow one, then I went to Bideford following it & it went really well in 2022. Trouble is once you start , you keep finding 50 year old problems. You’ll get there.
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It’s 31,000 and some now so who knows but looking at the pistons I’d say they are not of 1976 vintage so was it ever a 3CE when it left Slaters?
 
It doesn't look like there was much of a seal on the exhaust valve seats. Looks like the rings have corroded the bores when the bike has been standing and on two bores that wouldn't help cylinder compression. I had the same issue with a 400/4 I was resurrecting from a friends collection which had been standing for 16 years. The compression was down to 50psi across all cylinders and it was a non-starter, and required a top end rebuild and bore hone to restore to within tolerance and render it startable.
 
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