Topic: 1975 Honda CB125s - possible carburetor problem

[chriscraft42]

My bike has been acting really strange lately and I can't seem to figure what the problem is. First it has been a little difficult starting but when started needs to be at a high idle (2200 rpm)or it will stall. When I finally start to ride it runs fine until I come to a stop and then the bike stalls. I replaced the slow jet which someone recommended by I am still having a problem. I also have adjusted the air and idle screws to get it to idle correctly but it doesn't help...any suggestions...thanks

[scunny]

pull the carb and clean all the passages and jets

[mlinder]

also check for intake leaks.

[KingCustomCycles.com]

My bike has been acting really strange lately and I can't seem to figure what the problem is. First it has been a little difficult starting but when started needs to be at a high idle (2200 rpm)or it will stall. When I finally start to ride it runs fine until I come to a stop and then the bike stalls. I replaced the slow jet which someone recommended by I am still having a problem. I also have adjusted the air and idle screws to get it to idle correctly but it doesn't help...any suggestions...thanks

Yep, classic symptoms of an induction air leak or other sudden lean condition.  Spray wd40 around to find your leak. (that is all it is good for except scuffs on my kitchen floor)  If none show up, it is internal like a plugged carb jet or valves.  See post above.

[mattcb350f]

Could be carb, timing, valve adjustment, .........a good overall tuneup rules out a major problem.

...But I've got an CB125S which acted the same way. Would not idle at all and the lowest I could get it too was about 2000 rpm. Ran it for a little while then the problem got much worse.....Turns out a piston ring was broken all along.

Won't run without a lot of noise now 

Try a tune up, but that didn't fix mine.

 Matt.