125cc throttle issues

Ok, so I have a 125cc Chinese quad engine, with a Keihin 34 carb.

What happens, is it will start and idle quite well, and then when you touch the throttle, even the slightest bit, the rpms will spike right up! And even after it settles, it will stile idle fast.

I tried to clean it as best I could, and the adjustment screws didn't do anything.

Thanks for any help!
~BM88

Start with the basics first. Ensure that when you let off the throttle, the slide drops all the way onto the idle stop screw. Check cable play, springs, etc. Make sure you have no intake air (vac) leaks. With engine idling, spray carb cleaner all around carb base gasket and intake manifold. If RPMs change, check bolts, gaskets, boots etc. Post a pic of the carb for some more specific points.

Good stuff! I'll be sure to check. it's such a tight space, that it's hard to work on. I do know that the cable isn't functioning perfectly. I'll snap a photo in a few.

ok unscrew the slide from the carb it should slide out threw the top check the spring that pulls the cable back ive seen these springs fail and cause te carb to seem like its messed up or clogged

The spring is ok, although the cable is a little sticky.

I did check it by eye, and you literally can't even see the throttle open, but the engine will rev.

I haven't found a vacuum leak either.

im a dirt bike guy, I have a cr125 and an rm. It almost sounds like ure gas valve is stuck or the cable in the throttle tube is semi split?

hey where in nh are you from im from the keene area?

my gy6 had carb problems, and it was the vacum line from the carb to the emmission system. there was a line to the intake manifold so I just hooked the line from carb to the manifold, and it ran great! I don't know if this is your problem, but it improuves throttle response by 100%.

Does it run well otherwise? Sounds like your sticky cable, or maybe throttle slide in carb, needs cleaned and lubed.