cbr125 forum

We bought a 2006 carburetor CBR 125 r with 23k KMS on it early this year, for, cheap, because it wouldn't start. We took the carburettor apart and cleaned it and it started right away. But it was sluggish at first. After a few kilometers, it felt better. But it still didn't feel anything like the 80s CB 125 I drove when I was a kid. This accelerates slowly and won't go faster than 70 KMS/h on flat road.

We bought the performance kit from here and it made a difference, but not that much. It's still sluggish and I'm positive there's something seriously out of tune.

- the air filter is ok
- muffler is ok
- wheels spin freely
- it does not misfire
- it will rev to the max when idle/low gear (but slow responding, I'm my view)
- going uphill, there's no power
- clutch doesn't slip

The next thing I'm going to check is if there's a leak in the carburettor piston diaphragm - I've ordered a new one. That could very well be it, couldn't it?

This forum doesn't seem to be very active, but I'll post an update anyway in case someone else might benefit in the future:

The problem was the carb piston/diaphragm. Once I replaced that, the engine power was back to normal.