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

[sean brady scooters]

its quite a shame that tony cannot provide us with his primary comp ratio figures.............
it would have been after all ..........his best arguement against the whole low primary comp ratio thing...............and could have fully justified his comments against LPC...........

[tony]

Tony . . I believe MEC flywheels take about 10 tons to press and they tend to stay straight, unlike a very popular race crank that takes about 3/4 tons if it's a tight one

You have to think outside of that mate. When you press a crank together sure-thats a one off pressing .. however. In this case there is not much material around the pin with big masses of material acting as a lever on it as the surrounding mass had been machined away. So in effect you've increased the mass in the bottom part of the crank relatively speaking.. now what happens after running.. the crank gets hot and cools after each run/journey, the extra 'relative' mass is working away too. This all has an effect. This is why just saying "it takes ten tonnes' is great but it needs testing to prove its worth. I'm guessing with that thin area around the pin on the webs will be the downfall..it wont take as much heat/vibration to work away at itto get it out of true. We shall see.

[tony]

Going back to the infamous CE article, if you read between the lines you can pick out the info...first he refers to Gerry Pell (top LC tuner) that does work on his cranks.

Then in his tuning philosophy he refers to the combination of crankcase pressures, in combinatin with big pipes and madder porting etc. He next refers to packing the crankshaft as being 'old mans route' and the 'wrong way' . He outlines a standard Lambo with box pipe as being 1.65:1 and a modern motoX machine as being 1.2:1.....and the fact that on a Lambretta that runs a decent pipe, you actually need to increase the volume in the crankcase. He again goes on to repeat his statement yet again, that low crankcase compression is one of the keys to making good power, and that you have to have the right pipe to work with it.

Finally, in the section at the end called 'inside the beast' his crank spec is listed as: Modified Tino 'supercrank' webs, fitted with a long Japanese conrod and welded pin.

So you tell me......if HPC and crank stuffers are old mans route and the wrong way, and he repeatedly refers to crankcase pressure and crankcase volume as being key to making good power, he has top LC tuner Gerry Pell re-working his cranks, to use a long rod (presumably this a lower comp height piston with packer plate) and his crank webs are 'modified'.......am i completely mad to be thinking that Charlie is running an LPC crank similar to ours and similar to MBs??

Mark Broadhurst was using these types of cranks back in 1990, and the scooter it was in is still running! Sean Brady has been doing them for a similar period in Vespas, and has more recently (amid much negative speculation ) being turning them out for Lambos.

Now Mark comments the following:

OK, I asked Paul Baker what cranks they were using in Stuarts bike, they said a low primary one, I ask if he had problems and the upshot was I said I would see if we could make a balanced, tighter LPC crankshaft for them to test. SRP Racetec run an LPC crank too, and I built the one in the thread before I set off on the Euro. Interestingly, I spoke to a tuner who said they get 3-4 bhp more on a RB with a LPC crank! They can not get the power from an RB without lowering the primary compression!

So........we dont have the graphs to show you back to back....but the evidence is there for all to read, and interpret as they wish. Nobody except Charlie and a select few friends knows exactly whats in his crank case.....maybe he's scooping metal out inside there somewhere and its not off the crank, or maybe it is off the crank but in a different way....who knows....but those that want good power in either fast road or ractrack applications might find that little something they are looking for, in something like this by MBD:



or this by Sean Brady:

Can I just point out that Charlie does all his stuff in-house. From machining ,to cranks, to close ratio gearboxes..Gerry taught Charlie cranks in the earlies 90's but DOES NOT do Charlie's cranks. Charlie does the tuning/pipes and port work on Gerry's team racers and customer work. These machines vary from Tz's to Lc's to Tzr's. The current Gerry Pell Tzr250 British Championship winning bike is tuned by Charlie Edmonds..(The pipes are awesome btw )
Also Mark Broadhurst may of done what you call a 'lpc' crank years ago but the fact is his 'rolls royce' crank is a full circle today and up till now that has been his 'hi end' crank as advertised on his website.
I cant speak of sean because I simply dont know..However he has found something it seems and great.. not seen any back to backs on it though.

[tony]

its quite a shame that tony cannot provide us with his primary comp ratio figures.............
it would have been after all ..........his best arguement against the whole low primary comp ratio thing...............and could have fully justified his comments against LPC...........

I'm not arguing! Who said I was arguing? I'm certainly not arguing against the LPC-how can I ? I ride a Performance Tuning machine:D I can argue about the cranks tho..
I'm just sitting here loving it Mr Brady.
You've all heard or seen what Charlie did with the performance of my bike. It is tuned around his theories of course. And it works. And its early days for that motor with development to come.

[ralph95]

10 pages f**ck me you lot have to much time on your hands to write all this i have to say that lpc is not the be all and end all. reed valve and piston ported engine need a different approach. ask any tuner worth his salt and its not just the tune of any engine it's also about the RIDER and how good or bad they are anyway what do i know

[soullad]

I'm not arguing! Who said I was arguing? I'm certainly not arguing against the LPC-how can I ? I ride a Performance Tuning machine:D I can argue about the cranks tho..

So if Performance Tuning believe in LPC but its not necessarliy due to a redesigned crank - is it a combination of factors, esp the pipe then Tony?

[RinB]

10 pages f**ck me you lot have to much time on your hands to write all this i have to say that lpc is not the be all and end all. reed valve and piston ported engine need a different approach. ask any tuner worth his salt and its not just the tune of any engine it's also about the RIDER and how good or bad they are anyway what do i know

I tend to agree with you Ralph
As I said earlier there both good, dependent on how you use them.

I mean your Bl@@dy barrels have hardly any metal left on them, and the reed inlet are so big you could wear them as a Hat

But you get the most out of them from a balance of every thing

Smiffy

[paulmgreen]

The only way is a back to back dyno Dan .........come on son get yer finger owt .....

I would like to see all of the top tuners build a group 4 race moter. And then have a dyno day somwhere to see who has created the most power!

Its not all about outright power though...... usable power is important........ no point having 40+HP if its at 10,000 revs and on or off in terms of how its delivered! That becomes unrideable

I'm not arguing! Who said I was arguing? I'm certainly not arguing against the LPC-how can I ? I ride a Performance Tuning machine:D I can argue about the cranks tho..

So if Performance Tuning believe in LPC but its not necessarliy due to a redesigned crank - is it a combination of factors, esp the pipe then Tony?

Exactly........ all two stroke tuning - especially high end) is a combination of factors....... somethings work together well... some don't....... But the likes of Performance Tuning and SRP Race Tec are thinking the WHOLE thing through..... from ignition to exhaust...... and pushing each other in further continual development. Theres no single bolt on solution.

[Powolotti]

I spoke to a tuner who said they get 3-4 bhp more on a RB with a LPC crank! They can not get the power from an RB without lowering the primary compression!

it would be interesting knowing not only how much more power it made, but how much (if) the power was shifted in comparison to revs and how much (if) was lost before / at start of getting into the band.

Within GSF these type of cranks are used for around 2-3 years now on Veps with results that are good when only quoting dyno figures, but I am not 100% sure if I would use one in a road / touring scoot.

I can´t say if I will put one in a Lambretta engine, I don´t like too light cranks but in my case it´s 99% touring tunes...

Might get my head changed thou.

[Diablo]

10 pages f**ck me you lot have to much time on your hands to write all this i have to say that lpc is not the be all and end all. reed valve and piston ported engine need a different approach. ask any tuner worth his salt and its not just the tune of any engine it's also about the RIDER and how good or bad they are anyway what do i know

Quite a lot I would imagine. I had one of your old sidecar engines on the dyno earlier this year (now fitted in an old DTC bike). To say it was a little fruity to ride on the road is an understatement