End of SF1 restoration

Haggis said:
Hi Fabio. Great work there - the bike looks magnificent.

For me, the biggest 'surprise' when I got my Laverda 750 was that of vibration. Some seem to be smooth, but some, such as my SF(0), vibrate so much you can't see straight.

I hope your careful engine work brings smoothness and lots of pleasure

All the best from England, Paul
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Once tuning is spot on, it's the crank.
Paul
 
Fully agree with Paul. My SF(0) Engine was completely overhauled by OCT (Piet in fact I think). Crank was overhauled, too, carefully re-assembled and pressed together and balanced. The bike was running extremely smooth... For the 1000km inspection, I went back to OCT and Roger started it and was really surprised how smooth it ran (cudos to Piet's great crank- and engine assembly-job!).
 
Absolutely - healthy, well-tuned engine, it's the crank. My SF1 was one of the better SFs I ever rode from a vibe POV - and I've ridden a LOT of SFs. I don't know whether it was inconsistent factory work in balancing and truing that created so much difference, or things going out of whack due to a change during running or poor workmanship.

Piet is definitely a gun in this regard.
 
Haggis said:
Hi Fabio. Great work there - the bike looks magnificent.

For me, the biggest 'surprise' when I got my Laverda 750 was that of vibration. Some seem to be smooth, but some, such as my SF(0), vibrate so much you can't see straight.
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I’m aware of an SF here in Australia that the owner won’t ride due to how much vibrates.

The fact that you can’t tell which eye to look at when you talk to him confirms your
point. 😂
 
Instant indication that something is seriously wrong! Motor straight out and get to work. Or just leave it in the back of the shed and call yourself a Laverda ‘owner’ (ie not a rider)
 
Red’s CNC machined centre webs and joining piece would transform it. Whether phased to 270 or left as a 360. Machine down the outer SF webs similar to SFC and have it dynamically balanced and they’ll have a tasty motor. They might actually love it!
 
piranha-bro2 said:
Red’s CNC machined centre webs and joining piece would transform it. Whether phased to 270 or left as a 360. Machine down the outer SF webs similar to SFC and have it dynamically balanced and they’ll have a tasty motor. They might actually love it!
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Is a bog stock pristine SF. Collectors bike, not a daily, or occasional ride.
 
My 2 cents worth is that a stock SF in a perfect or near-perfect state of tune vibrates when compared to a triple or a modern twin. I'm not saying it's a vibration that is unsettling; it's a 180-degree twin that vibrates. I have owned both a 750 Norton and a 750 Trumpy from the 70s, both vibrated more than any 750 twin Laverda I ever rode.
2 weeks ago, I rode a low-mileage SF 750. At idle, the front axle bounced fore and aft. Once above idle speeds, when riding the bike was nice, smooth, and at 5000 rpm, there was a 180-degree vibration that let me know what I was riding, and the fun was about to begin, nothing that rattled the eyeballs. I had forgotten how much fun the SFs are to ride.... except for the drum brakes.
 
78jotadave said:
Once above idle speeds, when riding the bike was nice, smooth, and at 5000 rpm, there was a 180-degree vibration that let me know what I was riding, and the fun was about to begin, nothing that rattled the eyeballs. I had forgotten how much fun the SFs are to ride.... except for the drum brakes.
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Little correction, Dave - SFs are 360 degree twins, ie both slugs going up and down together, same as your Norton or Trumpet. The out-of-balance phases on 360 deg twins are fore and aft, when the counterweighting of the crank isn't counterweighted by piston movement. I think the factory cleverly designed the balance factor of the big twins to direct vibes in a tilted fore and aft plane - there are parts of the bike that suffer the effects of vibration more than others, which is probably why nearly every SF if ridden hard over the years will break the rear framer tube U and SF1s nearly all broke the instrument support bracket. But the handlebars and footpegs from my experience haven't ben too dramatic. As you say, it's always there, but doesn't make the bike unpleasant to ride - unlike one that has 'issues' and shakes like a shizebox (Nigel White's SF2 broke every lower rear engine mount on our ride together over the Nullarbor - the engine was hanging from the two studs under the tank!).

Balance of any 360 twin is very tricky stuff ... even rephased to 270 you will never have a motor that smooth in every part of the rev range. Even 180 deg triples have an inherent imbalance. Counterbalance shafts are incredibly effective - modern Royal Enfields and all the new 270 deg twins out there are amazingly smooth. Laverda could have produced the SF with counterbalancing and with a lighter crank, becauser the counterbalncing bobweights also act as flywheels.
 
My Laverda Atlas, 600cc counterbalanced twin, no idea what its crank phasing is. It's based on the 500cc 4 valve engine, which is very smooth up to and just past 5k that it's seen so far. Apparently, the road race trick was to remove the balance shaft to get more power. No idea why or whether that allowed vibrations to become noticeable. It's the first bike I ever owned that didnt vibrate, and that's a pleasant change from off-road singles or Britch twins that do a lot. BTW, my 3c vibrated like a mother when I first bought it, causing nubness in both hands, feet, especially over 4500rpms, but it's way better after a full Redax engine build. It still tingles, but I dont loose feeling in my extremities anymore.
 
Vince said:
My Laverda Atlas, 600cc counterbalanced twin, no idea what its crank phasing is.
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It's a 180. One up, one down. Perfect primary balance but produces a rocking couple (same for the 120 triple).
The balance Shaft aims to cancel out the rocking couple.
Search driving4answers on YouTube, has many well described videos on engine balance.
 
Thanks, Steve, reminded me of a conversation we had at one of the Bellegin Events where you were explaining the phasing of 180 triples, that 180 nonclaomer simplipys it to kindergarten level. From your explanation, including crank balance effects, it definitely isn't Kindagaren.
 
piranha-bro2 said:
Little correction, Dave - SFs are 360 degree twins, ie both slugs going up and down together, same as your Norton or Trumpet. The out-of-balance phases on 360 deg twins are fore and aft, when the counterweighting of the crank isn't counterweighted by piston movement. I think the factory cleverly designed the balance factor of the big twins to direct vibes in a tilted fore and aft plane - there are parts of the bike that suffer the effects of vibration more than others, which is probably why nearly every SF if ridden hard over the years will break the rear framer tube U and SF1s nearly all broke the instrument support bracket. But the handlebars and footpegs from my experience haven't ben too dramatic. As you say, it's always there, but doesn't make the bike unpleasant to ride - unlike one that has 'issues' and shakes like a shizebox (Nigel White's SF2 broke every lower rear engine mount on our ride together over the Nullarbor - the engine was hanging from the two studs under the tank!).

Balance of any 360 twin is very tricky stuff ... even rephased to 270 you will never have a motor that smooth in every part of the rev range. Even 180 deg triples have an inherent imbalance. Counterbalance shafts are incredibly effective - modern Royal Enfields and all the new 270 deg twins out there are amazingly smooth. Laverda could have produced the SF with counterbalancing and with a lighter crank, becauser the counterbalncing bobweights also act as flywheels.
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What's a few degrees between friends? Nullabor? SF, 3C, and the Gnomes SFC. Nothing broke.
 

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3CBRG said:
I rode a friend's 180 Jota with a Redax crank last year. Could not believe how smooth it was.
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My '78 1200 is incredibly smooth compared to my '78 Jota 1000; neither has Redax cranks. It is amazing how, over time, you get used to/grow into your bike. I've ridden the Jota for 45 years and the 1200 for just 3 years, mmm. Yeah, probably time to replace the clutch rubbers and rear wheel cush drive rubbers on the Jota, as they are the originals. The 1200 is smooooth!
 
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Beautiful work! Good to see there's at least one other my age having and riding Laverda! (my GT is a family piece)
Regarding vibrations, mine does vibrate a bit but it's roughly equal to my BMW, at certain revvs it is there but then again I have ridden and known only this Laverda and so no comparison to others. It has a (van Dijk) rebuilt crank -the 1987 invoice for the work is still with the bike ;)
 
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