impamentor
Full member
- Location
- New Forest, Hampshire
and what about the 6 eggs, were they organic and did you eat them raw like a real racer would. 
Graham
Graham
4 row primary Drive & Power outputs, Crank balancing, Con Rods, Alloy casting.
- Thread starter Jota Rob
- Start date
B
bob
Guest
Who did win the 4.40 at Uttoxeter? There's a blob of oil obscuring the result....
Nice shot of the crank Phil, I know they're chopping a bit more out them but folks are a bit shy of putting them up. Maybe if I start a thread on Crankshaft lightening, someone has some photos of some obscure works of art ?
Graham you keep the eggs, I dont think the pictures will surface. Think I read it twice, once on a report of an Italian specialist making fast triples, maybe scanned onto Laverpedia, from the 70's-80's and possibly on the Very beautiful Motodd raced in the early 90's, that white one ! but Im not sure....
Graham you keep the eggs, I dont think the pictures will surface. Think I read it twice, once on a report of an Italian specialist making fast triples, maybe scanned onto Laverpedia, from the 70's-80's and possibly on the Very beautiful Motodd raced in the early 90's, that white one ! but Im not sure....
G
Grant
Guest
Would it be fair to say the Laimboeck triples were the most highly tuned?
I would guess around 120bhp max, or can anyone elucidate further?
I would guess around 120bhp max, or can anyone elucidate further?
Tippie
Hero member
- Location
- Dr?bak, Norway
Piet, is this work something that we can be kept updated about?
When I did the SFC crank in my now racebike to 90deg I balanced it to 55% after much discussion. The more I researched the more it seems like witchcraft with so many variables to account for. I'm interested in other peoples experiences with them. No point fumbling around in the dark, it is no small easy job.
Red, do you have Carillos (and rollers) that would fit an SFC crank? Rods on 750 don't seem to be the issue they are on the triples but it is good to know what is available.
A super light crank doesn't always give the rewards all the work should bring. Tradeoff in tractability and weakness can bring it all apart. That Cook Nielsen Ducati that dominated AMA superbikes in the '70s had their own hand built crank from american steel, the original items kept breaking.
When I did the SFC crank in my now racebike to 90deg I balanced it to 55% after much discussion. The more I researched the more it seems like witchcraft with so many variables to account for. I'm interested in other peoples experiences with them. No point fumbling around in the dark, it is no small easy job.
Red, do you have Carillos (and rollers) that would fit an SFC crank? Rods on 750 don't seem to be the issue they are on the triples but it is good to know what is available.
A super light crank doesn't always give the rewards all the work should bring. Tradeoff in tractability and weakness can bring it all apart. That Cook Nielsen Ducati that dominated AMA superbikes in the '70s had their own hand built crank from american steel, the original items kept breaking.
Scrumpy
Hero member
Rob,
In the body of the article the figure of 160 is quoted, however you are correct it is a typo as confirmed by the specification section. The bike was Mk 5 Todd. Another interesting article was anout the work done by MEZ porting, reckon they produced 98BHP. Will post later.
Scrumpy
In the body of the article the figure of 160 is quoted, however you are correct it is a typo as confirmed by the specification section. The bike was Mk 5 Todd. Another interesting article was anout the work done by MEZ porting, reckon they produced 98BHP. Will post later.
Scrumpy
Unless you run them all side by side, I say its an impossibility. Different dyno's, was the quoted power at the wheel or clutch? correction factors.Grant said:
The one in texas Fort Worth ? that was "apparently" capable of "170 mph" was probably one of the most powerful.
Cheers Scrumpy !!
Scrumpy
Hero member
The article "Hot Toddy" Superbike February 1993 features a Motodd Mk5 Laverda with a Saxon frame and Saxtrac front end ridden by Dave Martin or Alan Cathcart. The article discusses a 22kg crank lightened by 6kg, head by George Mansfield. An interesting article.
The other article "Under Heavy Manners" Superbike September 1990 is also very interesting focusing on George Mansfield.
I think I would be contravening some IPR laws if I downloaded them onto this site, however is asked nicely (PM) I am sure an email would find its way into your in box.
Scrumpy
Rob - check your in box
The other article "Under Heavy Manners" Superbike September 1990 is also very interesting focusing on George Mansfield.
I think I would be contravening some IPR laws if I downloaded them onto this site, however is asked nicely (PM) I am sure an email would find its way into your in box.
Scrumpy
Rob - check your in box
Attachments
Scrumpy,
This very bike was on the Moto Witt dyno and managed 104hp at the clutch. Sorry to disillusion you, but that's what the read out stated.... On-road performance would also confirm this. At the time the bike was tended for by Paul Taylor and Alan Cathcart did the riding.
The most powerful Lav triple we ever measured was Mr. Witts' own hack, a 120?, 1150cc fitted with a DMC-based injection system. It was a worn and tired old banger at the time but made 112hp at the clutch. When fitted with carbs, power dropped to around 90...... like I said, a tired old banger! I'm extremely sceptical when anybody claims more than 110 ponies, need to see it to believe it! Back then, even Paul Taylor stated it was almost impossible to improve on the MKv as it was, the ports had been seriously reworked and was fitted with 40mm Dellortos. The inlet tracts are the achilles heel, they are just not suited to to yield more flow through natural aspiration. Gets you thinking about forced induction!
The stock crank weighs in at 18kgs, if the alternator rotor and sprag clutch are included, weight could reach 22kg. But, iIrc, the MkV was running an alternator and electric start. Lopping off 6kg is a bit over the top, I measured a factory 120? racing crank this summer, it weighed a shade under 16kg.
Tippie,
Work is still under way and by no means finished. I cannot disclose all details here, but you're right, lots of variables and possibilities. BTW, SFC rods are not the same as triple rods, only the big-end bearings. The 750 rods are 5 or 6mm longer than the triple rods.
We'll be working out the 270? variant too, worried a bit about the rocking couple that results but Phil T. has assured me it aint that bad.... 8)
We hope to come quite close to the SFC crank regarding overall weight, needing to use the stock rods does handicap a bit. Having ridden a fair few pukka SFCs, I am absolutely amazed at the engines' behaviour with the light crank. Best feature of the whole bike imho.... don't like much of the rest.
piet
This very bike was on the Moto Witt dyno and managed 104hp at the clutch. Sorry to disillusion you, but that's what the read out stated.... On-road performance would also confirm this. At the time the bike was tended for by Paul Taylor and Alan Cathcart did the riding.
The most powerful Lav triple we ever measured was Mr. Witts' own hack, a 120?, 1150cc fitted with a DMC-based injection system. It was a worn and tired old banger at the time but made 112hp at the clutch. When fitted with carbs, power dropped to around 90...... like I said, a tired old banger! I'm extremely sceptical when anybody claims more than 110 ponies, need to see it to believe it! Back then, even Paul Taylor stated it was almost impossible to improve on the MKv as it was, the ports had been seriously reworked and was fitted with 40mm Dellortos. The inlet tracts are the achilles heel, they are just not suited to to yield more flow through natural aspiration. Gets you thinking about forced induction!
The stock crank weighs in at 18kgs, if the alternator rotor and sprag clutch are included, weight could reach 22kg. But, iIrc, the MkV was running an alternator and electric start. Lopping off 6kg is a bit over the top, I measured a factory 120? racing crank this summer, it weighed a shade under 16kg.
Tippie,
Work is still under way and by no means finished. I cannot disclose all details here, but you're right, lots of variables and possibilities. BTW, SFC rods are not the same as triple rods, only the big-end bearings. The 750 rods are 5 or 6mm longer than the triple rods.
We'll be working out the 270? variant too, worried a bit about the rocking couple that results but Phil T. has assured me it aint that bad.... 8)
We hope to come quite close to the SFC crank regarding overall weight, needing to use the stock rods does handicap a bit. Having ridden a fair few pukka SFCs, I am absolutely amazed at the engines' behaviour with the light crank. Best feature of the whole bike imho.... don't like much of the rest.
piet
jotacorsa
Hero member
- Location
- between Santa Fe and Taos
i wonder if anyone tried the SFC rods on a triple with custom pistons....
6kgs off a triple crank? sounds like an article about cico many years ago
6kgs off a triple crank? sounds like an article about cico many years ago
B
bob
Guest
Regarding balance factors and such like , here's a tale which might be of some interest.
When building up my Atlas race engine I deliberated for some time over the balancer shaft, which is a big heavy lump weighing over a kilo [very different to the 500s diminutive balancer]. In the end I binned it, we also fitted a set of oversize Asso race pistons which were actually heavier than the standard Atlas ones . Because of these quite radical changes I assumed that we would have to rebalance the crank to compensate.
Pip, [the engine builder] said that because we didn't have any meaningful data to refer to , there wasn't much point in re balancing the crank. His advice was to screw it all together very carefully and see what it felt like in the bike, if it was horrendous then at least we'd have a starting point to improve upon. I was expecting it to behave like a jackhammer but the engine is actually very smooth, smoother than my old SFC in fact, which had a very nice motor. The compression is quite high at 11.8 to 1 , which mean that when you start it up you are aware there is a grunty parallel twin fitted in the bike, but no way is it intrusive. Sometimes I think we can try and second guess problems which in practice don't actually manifest themselves.
I'm just starting to build a spare 550cc motor now using some of Red's Carrillos and a set of Scott's pistons... I'll be throwing away the balancer on that motor as well, hopefully it will work out as nicely as the Atlas
When building up my Atlas race engine I deliberated for some time over the balancer shaft, which is a big heavy lump weighing over a kilo [very different to the 500s diminutive balancer]. In the end I binned it, we also fitted a set of oversize Asso race pistons which were actually heavier than the standard Atlas ones . Because of these quite radical changes I assumed that we would have to rebalance the crank to compensate.
Pip, [the engine builder] said that because we didn't have any meaningful data to refer to , there wasn't much point in re balancing the crank. His advice was to screw it all together very carefully and see what it felt like in the bike, if it was horrendous then at least we'd have a starting point to improve upon. I was expecting it to behave like a jackhammer but the engine is actually very smooth, smoother than my old SFC in fact, which had a very nice motor. The compression is quite high at 11.8 to 1 , which mean that when you start it up you are aware there is a grunty parallel twin fitted in the bike, but no way is it intrusive. Sometimes I think we can try and second guess problems which in practice don't actually manifest themselves.
I'm just starting to build a spare 550cc motor now using some of Red's Carrillos and a set of Scott's pistons... I'll be throwing away the balancer on that motor as well, hopefully it will work out as nicely as the Atlas
Bob,
With the Atlas engine having a 180? crank, it behaves much the same as an opposed twin, ie, if both pistons, rods etc are equally balanced, it will be quite ok vibe wise. The balance shaft is used to counter the rocking couple inherant with a 180? twin and depending on the distance between the cylinder centres, it may or may not make itself felt. With balance factors ranging from 50 to 70% for parallel twins, there is quite some scope catering for different piston weights.
piet
With the Atlas engine having a 180? crank, it behaves much the same as an opposed twin, ie, if both pistons, rods etc are equally balanced, it will be quite ok vibe wise. The balance shaft is used to counter the rocking couple inherant with a 180? twin and depending on the distance between the cylinder centres, it may or may not make itself felt. With balance factors ranging from 50 to 70% for parallel twins, there is quite some scope catering for different piston weights.
piet
phil37
Hero member
- Location
- Lincolnshire
Hi Tippie - Did you baance your 90 degree crank as 2 singles or as the whole twin? I did mine as 2 singles as opinion at the time in the Uk thought this was best - shame I never took a photo of it as it looks a treat -Regards - Phil