Scooterotica

Just got the throttle cable fitted. Had to fit a longer one and come in from the kick start side but got a nice smooth curve. The problem is the throttle is not returning on its own. Any ideas? Do I need a stronger spring?

Have you changed the grips as well?

Check the simple things... failing that a few people are selling the throttle return springs that fit within your headset

Yes I have fitted new grips but tried to make sure they are not right up against the switch housing. I’ve not seen the springs you mentioned that fit in the headset. I’ll have to trawl the net to see if I can find anything out about them.

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Thanks for the pointers. The control spring seems like a good solution. However, I have seen a few threads on similar subjects and some suggest the throttle should not return as when hand signals are used the throttle would close and there would be an obvious loss of power and speed. I am pretty sure mine self closed prior to stripping down (but can't be 100%). I know I never gave signals for right turns for this reason, just used the life saver and a blurry legshield stadium mirror. I have ridden bikes of all styles and sizes for around 30 years and never had one that the throttle intentionally stayed open on. I think I would prefer self closing.
I think the issue with mine is more likely the front brake cable and the new headlight switch wiring being tight on the control rod. I slapped plenty of grease on but there is still resistance.

You are quite right to say the throttle is intended to stay put.
Lots of folk get very agitated when I point this out. Nonetheless it is how the throttle was designed to work, for the reason you mention (right turn hand signals)
However, if you want yours to self-close? It can be achieved by leaving out the shims that go on the handlebar before fitting the throttle tube.

Sorry but I don't agree. The throttle rod in the headset is probably clogged with 50 year old grease, I'd strip it down, clean it up and lubricate it with some 3-in-1 oil. When I've done this and replaced the cable etc the throttle snaps back nicely.

I am currently restoring the Lammy so it is completely clean with new cables, headlight switch, brass olives and stainless steel olive clamps. The only things I have not replaced are the control rods. I have applied grease to the control rod where it rubs against the front brake outer cable and the switch wiring. I have had a couple of friends check there throttle closure and all are self closing. I have bought one of the JPP return springs so have that option. I do however, think it is not a bad thing for the throttle to stay open so right hand signals can be used. I will prep the control rod ready to fit the spring and reassemble as is and see how it goes. I can always fit at a later date if necessary.

Much safer that it doesn't close quickly.