I cleaned up the throttle assembly as it has always been stiff and I would have to twist it shut with force.

I cleaned the accelerator and deccelerator cables with petrol then lubricated them with ACF50. The cables themselves move freely now. The throttle assembly spins around and its still loose with the cables fitted. However with both of the cables attached to the carburettor cam, the throttle is really stiff, more so than before. The carburettor cam snaps back but won't move with the cables attached.

Should the throttle on the NC30 not snap shut? I can't figure out any way of loosening it up.

mine snaps shut immediately. have you checked the cable routing is correct? (wondering if that's in the manual somewhere...)

I managed to solve the stiff throttle. I didn't thread in the accelerator cable enough into the throttle assembly. I can twist it freely now but it still does not snap back. I can open it at any position and it will remain in that position. The Haynes manual shows bugger all, same with the Honda service manual, infact theres no mention of the throttle cables in the latter. The front end moves lock to lock with no resistance and the cables don't tug. I think I have the throttle cables routed right.

I took some photographs:

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looks very similar to where mine are (just looked). daft suggestion maybe, however is your grip clear of the bar end? mine wasn't when I got it. adding a washer made the throttle so much better...

Yeah its clear. Could spin it around. Just odd how everything is lubricated and moves freely yet when all connected the throttle doesn't snap shut.

Make sure the return cable isn't too tight, that'll stop it snapping shut.

Druid

Im having a simliar problem.. let me know if you figure it out..

I have removed the return cable altogether on my NC's. It makes setting everything up and taking the carbs off and on much quicker. You also can't use a standard return cable with mnay quick turn throttles (which both mine have).

It doesn't do anything in normal use it's only needed if the carb throttle return spring snaps: not likely!!

is the cable at a sharp/twisted angle?

the honda service manual I have shows a few (albeit basic) diagrams of cable routing. PM me if you want me to share.