Topic: 1975 cb125s carburetor problem

[chriscraft42]

I am having  a possible carburetor issue. If I rev the engine passed 5000 rpm the engine sticks at 5000 rpm and actual even revs higher then that. The only way to bring the engine back to normal idol is to move the throttle back and forth. The throttle is not sticking! It is something in the carburetor. Would anyone have any ideas or suggestions that would help me....thanks

[333]

Unscrew the top off the carb.  It should come out with the throttle valve and needle as an assembly.  Work the throttle and observe if it moves freely. The throttle valve(round cylinder) must move freely in the body of the carb.  Use your finger to check the body of the carb  The needle should not be bent in any way, so it will slide freely into the jet(below the passage way that the air comes through.  Remove the needle and the circlip(remember which ring the clip was in), and rool it on a flat surface to check if it is bent.

If all these ideas check out.... I got nothing more.

[Kevin D]

Ditto what 333 says: Have you had the top of the carb off to inspect the slide? It should be nice and clean as a whistle and go up and down smoothly.  The spring below the top pushes it back down. If it wont go up and down smoothly when out of the carb maybe you have a kinked cable. Make sure the side of the slide with the cutaway at the bottom goes toward the air filter.