Crank replacement

[cgarland@sky.com]

I am upgrading my Jet200 engine with Casa225 kit and ignition and have also purchased a SIP uprated gp crank and bearings to go with the kit. The overall length of the crank from outside edge of the flywheel thread to the outside edge of the drive splines is approx 25mm longer than the original Jet crank, is this correct or have I ordered the wrong crank?
Also the Sticky book says that the flywheel bearing, as it is being replaced, will need a new collar/track/sleeve. Is this correct in my set up as I cannot find these collars on any supplier’s website?
Thanks
Colin

[corrado]

I'm not familiar with none GP cranks so can't help with the length but you will need an NU2205 bearing for it and the "track" is part of the new bearing and you remove it from the new bearing (it's not fixed) and fit it to the crank. The old bearing would have been an NU205 which is thinner and required a thin metal spacer when fitting it. You don't use that spacer with the new GP bearing.

[Warkton Tornado No.1]

I am upgrading my Jet200 engine with Casa225 kit and ignition and have also purchased a SIP uprated gp crank and bearings to go with the kit. The overall length of the crank from outside edge of the flywheel thread to the outside edge of the drive splines is approx 25mm longer than the original Jet crank, is this correct or have I ordered the wrong crank?
Also the Sticky book says that the flywheel bearing, as it is being replaced, will need a new collar/track/sleeve. Is this correct in my set up as I cannot find these collars on any supplier’s website?
Thanks
Colin

The change to an uprated roller bearing has been explained extremely well, but are you saying that the overall lengths of the two crankshafts are 25 mm different?

I just wanted to clarify what the issue is, please.

[ULC Soulagent]

Find the link that u used too buy it from and post it up here

[cgarland@sky.com]

Thanks for the bearing info, I understand that now.
With regards to the crank length, yes the gp one is 25mm longer between the outer edge of the flywheel thread and the outer edge of the drive spline end.
Cheers

[cgarland@sky.com]

http://www.lambretta.co.uk/shop/cranksh ... -7406.html

This is the crankshaft replacement that I have.

[Warkton Tornado No.1]

As far as I understand the various SIII & GP motors that all use similar crankcases/magneto housings of a 'generic' geometry, the appropriate flywheel will always be placed axially in the correct position to function within the flywheel cowling.

Having swapped the flywheel centres for a good flywheel from one type taper to another, apart from nominal differences, I have never encountered any variation as much as the 25 mm mentioned here.

That said, if you know that the consequences of using the new crankshaft will move the flywheel outboard a significant amount, there is something wrong. That scenario is not difficult to prove prior to any assembly of the motor. Just a case of shoving the flywheels onto their mating crankshafts & measuring from fan/flywheel to crankshaft web should prove it. By the sounds of it you have already laid the crankshafts side by side to establish where the difference lie, with all indications being the flywheel side.

If it were my two hundred quid, I'd reckon that'd entitle me to a lot of after sales care & attention, so if you check as suggested & prove your concern, get on to the seller.

Of course, it would be useful for you to let us know the outcome, please.

[cgarland@sky.com]

I will recheck but know I’m not too far off with the 25mm, I have a photo but don’t think I can post it here. I have had a comment on a Lambretta tuning facebook site that this is normal as the gp crankshaft taper goes further into the gp flywheel.
Thanks for your assistance.
Regards