Scooterotica

aha,

I ve not really said much on this as people are talking the right vibes here which is brill

I showed early in thread the Lamy crank with bell shape.

Well look at this Bike crank look what the big boys have done



Here they have belled the crank but not all the way and have actually designed a scoop as well.

Ive also seen crank with fan like shapes on the outside edges of crank webs.
Hard to discribe but look at a flywheel fans and superimpose that onto the crankwebs
Whish I could find Blady pics

What would this do...... lets now real discuss

Smiffy

do you have a bigger picture of this crank smiffy? I am not sure what they have done

"turbo" slot adding was quite popular in the RD scene but it killed many cranks as this took away lubrication from the bigend bearing (so they say)

RinB wrote:
.........
Ive also seen crank with fan like shapes on the outside edges of crank webs.
Hard to discribe but look at a flywheel fans and superimpose that onto the crankwebs
Whish I could find Blady pics

What would this do...... lets now real discuss

Smiffy

like this for the Piaggio Ciao Moped :

it is quite "OLSCHOOL" tuning from mid 80is !

look at the fans at the crankweb, I am looking for better photos.

here better photos:





upps, a little big !

Yep thats it lads
and yes Powolotti I believe big ends might have had probs

All good stuff

Smiffy

Avantone wrote:How are cranks balanced in practice in the context of the rod/gudgeon pin/piston/rings etc?

This will help go with the info already posted...

Yes all very interesting. I found some twin 2 stroke cranks on the net which had similar modifications.
http://www.twostrokeshop.com/two_stroke ... ngines.htm

With regard to balancing I have been trying to balance flywheels between turning centres but I must have got the taper angles wrong because I am getting sticktion problems. I've been on the look out for some knife edge rollers for ages which I think is the most accurate way of doing flywheel and crank balancing.
Wouldn't be surpised if you were to find a crank like that being discussed in the top group four bikes.
I gather Charlie favours LPC and makes his exhausts do all the work.
The difficulty I think will be with the exhaust as anything off the shelf will always be a compromise.

drunkmunkey6969 wrote:

Avantone wrote:How are cranks balanced in practice in the context of the rod/gudgeon pin/piston/rings etc?

This will help go with the info already posted...

Dan,

I feel like I've sat through a David Lynch movie watching those! WTF was that all about?

Video 1. Twiddles with end of conrod and put on scales repeatedly

Video 2. Spins crank round for no apparent reason

Video 3. More spinning with a object taped into the small end

I'm even more mystified! I would have thought proper balancing would include the Piston/Gudgeon Pin/Rings/Small End/Shims/Circlips etc, as well as the front sprocket and Flywheel................

Avantone wrote:

drunkmunkey6969 wrote:

Avantone wrote:How are cranks balanced in practice in the context of the rod/gudgeon pin/piston/rings etc?

I feel like I've sat through a David Lynch movie watching those! WTF was that all about?

Video 1. Twiddles with end of conrod and put on scales repeatedly

Video 2. Spins crank round for no apparent reason

Video 3. More spinning with a object taped into the small end

I'm even more mystified! I would have thought proper balancing would include the Piston/Gudgeon Pin/Rings/Small End/Shims/Circlips etc, as well as the front sprocket and Flywheel................

Tend to agree Tony

Unless all there doing is getting a basis crank pre balanced.

Ie when you buy a crank from a supplier will they have balance a crank with piston shims bearing etc ect. I wouldnt thought so

Like you said to do a true balance of the crank system you would really need all the items you listed.