Just put my carbs back in today after a couple of weeks sorting out the jets and getting valve clearances done. After re attaching the push/pull cables to the carbs I noticed that the throttle is now sticking open and only returning very very slowly. The throttle was fine a few weeks ago before I removed the carbs which made me think it was possible I could of damaged the return spring on the carbs when I had them on the bench. However this is not the case as I removed the cables and manually opened the part on the carb and it snapped shut when released. It seems it's definitely the cables but I can't work out why. The routing hasn't moved from how it was before and seems correctly routed after looking at other posts. Any thoughts on what I might of done or how this may be resolved would be much appreciated.

Sometimes they just like to piss you off.

Give them a lube, check they aren't caught on anything, and have a fiddle with where they are running but don't change the routing.

I don't run a return cable as I find it pointless and makes it a pain in the arse to route the cables like you've found.

Ok mate. Will give this a try. Do I need to buy cable lube or will I be ok to spray a little chain lube down the lines?

I just use WD40

Hi Bikemonkey... Just something to think about (My dad had it happen once so I am very aware of it ) and he had the throttle stick open on a very strong racecar while testing on the road (new race pedal setup being tested went overcentre and locked the throttle open)... trying to reach for the key to switch the car off felt like it took an eternity (and while the brakes are race grade they did nothing to slow progress) - he didnt want to hit the clutch and have the car overrev (we werent sure where the limitter was set). Luckily on a bike the kill switch is right there and you could pull in the clutch and let it bounce off the limitter (I actually dont know if an NC30 has a limitter?), but it all involves a fair amount of panic. Personally I like to have that second cable there to force the carbs shut.

tigerclaw wrote:Personally I like to have that second cable there to force the carbs shut.

That's great if it helps you sleep at night, but you would probably need 4 or so throttle return springs (there's more than 1) to fail for this to happen on nc30 carbs.

I've never run a return cable and never will.

steve85 wrote:Just put my carbs back in today after a couple of weeks sorting out the jets and getting valve clearances done. After re attaching the push/pull cables to the carbs I noticed that the throttle is now sticking open and only returning very very slowly. The throttle was fine a few weeks ago before I removed the carbs which made me think it was possible I could of damaged the return spring on the carbs when I had them on the bench. However this is not the case as I removed the cables and manually opened the part on the carb and it snapped shut when released. It seems it's definitely the cables but I can't work out why. The routing hasn't moved from how it was before and seems correctly routed after looking at other posts. Any thoughts on what I might of done or how this may be resolved would be much appreciated.

I got absolutely the same when I did my NC35. It seems the cables are very sensitive to how they are routed down to the last few fag papers either way, and I also suspect that at least on the 35, where they go between the rad and frame can be a pinch point. I even managed to break the opening cable when wiggling everything around and opening and shutting the throttle. Not even lubing both cables made a difference, and the brand new one also stuck. In the end, a minute adjustment of the freeplay in the opening cable fixed it, although I'm sure I have a little too much now!

Legendary advice guys, a squirt of wd and a slight adjustment on the cable and all of a sudden as if by magic it works fine.