SR125 idling really quickly, how to fix?

To avoid a longish story, the other night in an attempt to get this bike to actually start, I spent about 20mins arsing around with carb and throttle settings before noticing that I’d not connected the HT coil properly. I returned it to the factory settings (as per the Haynes manual), and now it’s running incredibly fast. Previous to this the engine was running fine (in a different frame) and before that I had the carb in bits for cleaning.

The carb is a Teikei Y24P apparently, but I can’t find any information about it anywhere.

Engine turns over, starts first time, but the revs climb very quickly (there’s no revcounter, but it’s far higher than I’d be happy to ride it), with no apparent way to reduce them. The idle screw is far enough out as to not be affecting the throttle at all, and the throttle itself seems to be moving properly.

Any ideas?.

To check the throttle we removed the airbox, but the symptoms are the same with the airbox attached or removed. I’ve just noticed that I’ve not checked what the spark plug’s saying wrt the fuel/oil mixture, so if/when someone’s at home I’ll get them to do that and let me know what it says.


Anything weird happening with revving? (Slow response, slow to return etc?)

Choke’s fine, moving it makes no difference.

Opening the throttle makes the engine go quicker, but only ever so slightly (I don’t want to make it go much quicker). Closing the throttle makes the revs drop slightly and slowly, but not back to the previous ‘idle’.

In terms of the movement of the grip/cable, that’s all fine. It’s a touch rough (which I know is caused by the cable), but that doesn’t seem to be affecting the movement at all.

try manualy closing the throtle at the carb

Heh, this is slightly embarrasing, especially in light of my forgetting to connect the ht coil, but the issue was that the tube holding the throttle cable wasn’t seated properly, so was pulling ~4mm of cable through which, somehow, didn’t make the carb look too wrong to me.

your cab - does it have an idle setting? most do i think