The end of the Lambretta crank as we know it ???

[sean brady scooters]

i may be wrong of course...............and am only expressing my personal veiws here ...........
but i think the full circle mb crank was the best suited to the market requirements...................
that is to say..............that most customers,required the best /reliable performance from the strongest crank available............used with quite low revs/max torque................
hence the use with the MB overall set up............

[tony]

I expect to see new pipes designed to work with the new crank. I will voice my doubts about the strength of the cutaway ones mind you.

[sean brady scooters]

i,m sure you will Tony......................

[tony]

[156 D]

This article is very interesting........it is a shame though that when some seem to disagree with one (but only as a discussion)then the other takes umbrage and then say`s...it`s "not for you, but us".. .....also i don`t think some folks are confused as the ones answering replies are well into what they are talking about.....there are so many people with so many theories...so here are mine....The Vespa is a completely different engine layout to a Lambretta so you cannot really compere....I have owned both in the sixties for some time and i believe the Vespa comes out on top for everything........On the drive side of things the Vespa is a more direct continuous drive through it`s gears or cogs, flywheel on one side of the crank and the clutch and gears on the other, probably the reason for smoothness and more instant traction......the Lambo has the chain drive pulling on one side with no support at it`s outer end, maybe the reason for cracked cases, i believe that contributes to the vibration and not the size of the web on the crank....LPC can ONLY work with an efficient expansion box, not more likely too......also

If you look at some of the reed manifolds available for them especially the MB of NK ones they must reduce primary compression by loads and I've seen plenty of reedvalved 210s not make as much hp as std carb jobs.

Good post, but in that particular instance, would the loss not be more to do with the length and volume of the inlet tract, and the loss of velocity, rather than LPC in relation to volume?

............as Al says, low gas flow would indeed be in an engine with LPC.......the lower the LPC the lower the gas flow and the lower the induction vacuum which would contribute to the inlet tracts loss of velocity not the length or volume of it`s tract..........a long narrow tube cannot be the cause of it`s own velocity...........the amount of velocity is due to the amount of vacuum at it`s outer end....the crankcase.......so in theory a low LPC would intake less fuel resulting in less BHP......

.........we all know the design of these engines are some 60 yrs old ........so the engineers have had all the time in the world to make them better all round........they say what`s been around ,comes around, so are we really just disappearing up our own exhaust pipe ......in the `60`s most who owned a scooter were aged up to 18 then bought a car, now it`s more like 35 to 50yrs who own one ......just ripe to spend all that inheritance money on a very expensive hobby...............

[RinB]

I saw the crank at the euro

I wondered how long it would take to start talking about it.
Just what Mark said " Ive put it on stand for you Forum Guys"

He has only made a couple for certain Racing people as they have asked him to produce some.

But back to LPC, the crank alone will not lower the PCR that much
When you look at the calcs for PCR, removing this amount on the webs would reduce PCR by very little.

Alot more has to be removed from else where to get to the ellusive 1.2

Smiffy

[davidblythe]

I saw the crank at the euro

I wondered how long it would take to start talking about it.
Just what Mark said " Ive put it on stand for you Forum Guys"

he was a bit more disparaging as i remember when our crowd raised the topic of conversation

[RinB]

I saw the crank at the euro

I wondered how long it would take to start talking about it.
Just what Mark said " Ive put it on stand for you Forum Guys"

he was a bit more disparaging as i remember when our crowd raised the topic of conversation

[Avantone]

I can't see the point of the debate............ The low vs. high debate has been made loads of times.

Most people go with what they've understood from books and articles and these quickly become folk-law or undisputed fact, whereas the people that actual have some scientific evidence/experience either "lurk" on these forums without contributing or simply won't (can't) say! (and I wouldn't either! )

I think the quote attributed to MB is interesting and more than a little mischievous - How would you market a crank like this? what is it supposed to do? where is the evidence? what exhaust do I run with it? do you actually sell it?, and would YOU part with your hard earned cash for something that has no published performance advantage (if it has, post it up............. )

And if you do want to go down the LPC route, is this the way to do it? (not for me)

By the way, FALC does a €1600,00 crank for a Honda GP1, and guess what ........................... it's round!

[drunkmunkey6969]

By the way, FALC does a €1600,00 crank for a Honda GP1, and guess what ........................... it's round!

Isn't that a four stroke?