I ordered some new inner cables from a well known shop and online store for my 64 LiS 150 . The original 54 year old outer cables are still in reasonably servicable condition so I will try and conserve them as long as I am able to.
When the cables arrived I noticed that the throttle cable inner, ( a CasalambrettaUK part ), was quite a bit thicker than the original inner that it was replacing. In fact it was the same thickness as the gear cables or the clutch cable and the same as the front brake cable inner ? original throttle inner 1.2mm ......new Casa jobbie 1.5mm
Naturally it isn't going to fit the original cable outer without some devine intervention
I asked for a replacement and it duly arrived the very next day ..exactly the same spec ??
(amazing customer service by the way ).The larger the inner cable diameter, the larger the circumference, the greater the surface area, the higher the cable friction, which is the very last thing that you'd want on a throttle cable. If I could be bothered I'd calculate the increase in friction... but I can't ....so I won't
The larger 1.5mm cable diameter is also going to be considerably less pliable than the 1.2mm cable too which means that there is going to need to be an increase in effort required to twist the throttle due to the stiffer cable trying to conform to the small diameter of the brass throttle wheel .
This increased cable friction and lower pliability is likely to lead to sticky throttle operation and slow return to idle, particularly if the throttle cable routing is not kept to gentle bends as the carburettor slide return spring has very little strength.
Anyway i just thought you lot needed to know that because I'm grumpy this morning from lack of sleep and the missus is out so I can't offload my frustration on her delicate shelllikes.
Oh and the answer ?..... yes I'll go raid my bicycle gear cable inners which not surprisingly are exactly the same 1.2mm thickness as the original cables and a damn sight cheaper too!.........in fact I'm going to check if my cycle brake cable inners are a match for Lambretta gear clutch cables and save myself some money.