Crank options for mild Lambretta tune

[storkfoot]

I think bristolmod was quite fortunate not to have his points bouncing all over the place on a mugello. Several years ago, I wasn't so fortunate. Very quickly went GP crank electronic. The improved overall performance was very noticeable

[victor]

Without turning this into a points vs electronic discussion, there are 2-stroke classic motorbike racers that rev between 10 and 15k rpm on points so there shouldn't be any physical limitation besides the construction of our points which most likely is quite different from theirs...

Anyway, looking forward hearing about any problems with Tv/Li cranks and tuning...

[dave wheeler]

i think your big problem is going to be finding a suitable piston for that bhp compatable with a tv rod length, i think the rb kit uses a 116mm rod so that piston could be an option but when i got my standard tv rebored the selection of pistons, especially 2 ring types was limited to indian ones of uncertain quality, ended up using a 3 ring vertex, whereas there is a wide choice of 64mm pistons for a 107mm rod

[victor]

i think your big problem is going to be finding a suitable piston for that bhp compatable with a tv rod length, i think the rb kit uses a 116mm rod so that piston could be an option but when i got my standard tv rebored the selection of pistons, especially 2 ring types was limited to indian ones of uncertain quality, ended up using a 3 ring vertex, whereas there is a wide choice of 64mm pistons for a 107mm rod

Yes, but in case I'm keeping the crank i'll be using the kitted piston and packing plates to make up for the conrod length difference, if possible...

[bristolmod]

can you pack out that far? I wouldn't have thought so

Chris

[corrado]

Dunno if I missed it but what barrell / kit are you planning on using? The Mugello kits & pistons are available to suit TV cranks without the need for any packers. You can use a std piston with a 9mm packer [speak to Dan or Darrel about those].

[victor]

99% going for the BGM RT when out...

[goldeneye]

run a black MEC EUR race crank in mine, been in 5 years no bother. they were only about 70 quid at the time, but have went up in price to 120 or so since. the scooter restorations S.I.L. crank with jap main bearing for 80 quid -ish will do you fine, people have been converting indian cranks to this spec for years to make a reliable crank. the thing with your TV crank will be more the strength of the taper,which is a lot thinner than a GP crank taper.

[victor]

Seems to be various advice whether the Li taper is strong enough or not. Has anyone had or had a friend who's crank broke at the taper?

[bristolmod]

the only damage I've had in that area in the last 45 odd years was a TV200 which sheered the flywheel off (original crank was fine). I understand that this was a common problem with early TV200's of which mine was, and the flywheel nut was redesigned to "eliminate the problem"

Having said that with the arrival of GP200 and the increased power as standard, a new crank was introduced, so it was a weak spot which Innocenti were aware of.

It certainly helps if you lap the flywheel onto the taper using grinding paste so there is no movement however minute.

Chris